U.S. patent application number 16/201841 was filed with the patent office on 2019-06-13 for compact optical engine and method of manufacturing same.
The applicant listed for this patent is North Inc.. Invention is credited to Douglas R. Dykaar, Syed Moez Haque, Rony Jose James, Martin Joseph Kiik, Stefan Mohrdiek, Jorg Pierer.
Application Number | 20190179155 16/201841 |
Document ID | / |
Family ID | 66657983 |
Filed Date | 2019-06-13 |
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United States Patent
Application |
20190179155 |
Kind Code |
A1 |
Pierer; Jorg ; et
al. |
June 13, 2019 |
COMPACT OPTICAL ENGINE AND METHOD OF MANUFACTURING SAME
Abstract
Systems, devices, and methods of manufacturing optical engines
and laser projectors that are well-suited for use in wearable
heads-up displays (WHUDs) are described. Generally, the optical
engines of the present disclosure integrate a plurality of laser
diodes (e.g., 3 laser diodes, 4 laser diodes) within a single,
hermetically or partially hermetically sealed, encapsulated
package. Such optical engines may have various advantages over
existing designs including, for example, smaller volumes, better
manufacturability, faster modulation speed, etc. WHUDs that employ
such optical engines and laser projectors are also described.
Inventors: |
Pierer; Jorg; (Alpnach,
CH) ; James; Rony Jose; (Alpnach, CH) ;
Mohrdiek; Stefan; (Affoltern am Albis, CH) ; Dykaar;
Douglas R.; (Waterloo, CA) ; Kiik; Martin Joseph;
(Waterloo, CA) ; Haque; Syed Moez; (Kitchener,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
North Inc. |
Kitchener |
|
CA |
|
|
Family ID: |
66657983 |
Appl. No.: |
16/201841 |
Filed: |
November 27, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62591030 |
Nov 27, 2017 |
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62591550 |
Nov 28, 2017 |
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62597294 |
Dec 11, 2017 |
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62608749 |
Dec 21, 2017 |
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62609870 |
Dec 22, 2017 |
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62620600 |
Jan 23, 2018 |
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62760835 |
Nov 13, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01S 5/02216 20130101;
H01S 5/02292 20130101; G02B 27/0176 20130101; G02B 26/101 20130101;
H01S 5/4087 20130101; H01S 5/4093 20130101; H01S 5/042 20130101;
G02B 27/0916 20130101; G02B 2027/0178 20130101; G02B 27/0172
20130101; H01S 5/02248 20130101; H01S 5/0071 20130101; H01S 5/02296
20130101; H01S 5/4012 20130101; H01S 5/02224 20130101; G02B 19/0052
20130101; G02B 27/4205 20130101; G02B 2027/0174 20130101; G02B
19/009 20130101; G02B 27/102 20130101; H01S 5/02272 20130101; G02B
19/0014 20130101; G02B 27/0911 20130101; G02B 27/1086 20130101;
H01S 5/02288 20130101; G02B 2027/015 20130101 |
International
Class: |
G02B 27/01 20060101
G02B027/01; H01S 5/022 20060101 H01S005/022; H01S 5/40 20060101
H01S005/40 |
Claims
1. A method of manufacturing a laser projector, the method
comprising: bonding a plurality of laser diodes directly or
indirectly to a first base substrate; providing a coupling between
at least one laser diode driver circuit and the laser diodes, in
operation the at least one laser diode driver circuit selectively
drives current to the laser diodes; bonding a cap comprising at
least one wall and at least one optical window to the first base
substrate, the at least one wall, the at least one optical window,
and at least a portion of the first base substrate together delimit
an interior volume sized and dimensioned to receive at least the
plurality of laser diodes bonded to the first base substrate, the
bonding of the cap to the first base substrate providing a hermetic
or partially hermetic seal between the interior volume of the cap
and a volume exterior to the cap, and the optical window positioned
and oriented to allow light emitted from the laser diodes to exit
the interior volume; bonding a plurality of collimation lenses to
be adjacent the at least one optical window, each of the plurality
of collimation lenses positioned and oriented to receive light from
a corresponding one of the laser diodes through the at least one
optical window; positioning a beam combiner to combine light beams
received from each of the collimation lenses into a single
aggregate beam; and positioning at least one scan mirror to receive
laser light from the plurality of laser diodes, the at least one
scan mirror controllably orientable to redirect the laser light
over a range of angles.
2. The method of claim 1, further comprising: bonding at least one
of the laser diodes indirectly to the first base substrate by
bonding the at least one laser diode to a respective chip submount;
and bonding the chip submount to the first base substrate.
3. The method of claim 1, further comprising: bonding each of the
laser diodes indirectly to the first base substrate by bonding each
laser diode to a respective chip submount; and bonding each chip
submount to the first base substrate.
4. The method of claim 3 wherein bonding each laser diode to a
respective chip submount comprises bonding each laser diode to a
respective chip submount using a eutectic gold tin (AuSn) solder
process.
5. The method of claim 3 wherein bonding each chip submount to the
first base substrate comprises step-soldering each chip submount to
the first base substrate.
6. The method of claim 3 wherein bonding each chip submount to the
first base substrate comprises bonding each chip submount to the
first base substrate using at least one of a reflow oven process,
thermosonic bonding, thermocompression bonding, transient liquid
phase (TLP) bonding, or laser soldering.
7. The method of claim 3 wherein bonding each chip submount to the
first base substrate comprises bonding a chip submount that has a
red laser diode bonded thereto, bonding a chip submount that has a
green laser diode bonded thereto, bonding a chip submount that has
a blue laser diode bonded thereto, and bonding a chip submount that
has an infrared laser diode bonded thereto.
8. The method of claim 3 wherein bonding each chip submount to the
first base substrate comprises soldering each chip submount to the
first base substrate using a reactive multi-layer foil material
preform.
9. The method of claim 1, further comprising, prior to bonding the
plurality of collimation lenses, actively aligning each of the
plurality of collimation lenses.
10. The method of claim 9 wherein actively aligning each of the
plurality of collimation lenses comprises positioning each of the
collimation lenses to optimize spot and pointing for each of the
respective laser diodes.
11. The method of claim 1, further comprising: prior to bonding the
cap to the first base substrate, bonding an optical director
element to the first base substrate proximate the laser diodes, the
optical director element positioned and oriented to direct laser
light from the laser diodes toward the optical window of the
cap.
12. The method of claim 11 wherein bonding an optical director
element comprises bonding one of a mirror or prism to the first
base substrate proximate the laser diodes.
13. The method of claim 11 wherein bonding an optical director
element comprises bonding an optical director element to a first
base substrate using at least one of a reflow oven process,
thermosonic bonding, thermocompression bonding, transient liquid
phase (TLP) bonding, or laser soldering.
14. The method of claim 1, further comprising bonding the at least
one laser diode driver circuit to the first base substrate.
15. The method of claim 1, further comprising: providing the first
base substrate, wherein the first base substrate is formed from one
of low temperature co-fired ceramic, aluminum nitride (AlN),
Kovar.RTM., or alumina.
16. The method of claim 1 wherein bonding a cap to the first base
substrate comprises bonding a cap to the first base substrate using
at least one of a seam welding process, a laser assisted soldering
process, or a diffusion bonding process.
17. The method of claim 1, further comprising: prior to bonding the
cap to the first base substrate, flooding the interior volume with
an oxygen rich atmosphere.
18. The method of claim 1, further comprising: bonding a plurality
of electrical connections to the first base substrate, each
electrical connection coupled to a respective laser diode in the
plurality of laser diodes; bonding an electrically insulating cover
to the first base substrate over the plurality of electrical
connections; and providing a coupling between the at least one
laser diode driver circuit and the plurality of electrical
connections, in operation the at least one laser diode driver
circuit selectively drives current to the laser diodes via the
plurality of electrical connections.
19. The method of claim 18, further comprising bonding the at least
one laser diode driver circuit to a first surface of the first base
substrate, wherein: bonding the plurality of electrical connections
to the first base substrate comprises bonding the plurality of
electrical connections to the first surface of the first base
substrate; bonding the electrically insulating cover to the first
base substrate comprises bonding the electrically insulating cover
to the first surface of the first base substrate over the plurality
of electrical connections; and bonding the cap to the first base
substrate comprises bonding the cap to the first surface of the
base substrate and bonding the cap to the electrically insulating
cover.
20. The method of claim 18 wherein: bonding the plurality of
electrical connections to the first base substrate comprises
bonding the plurality of electrical connections to the first
surface of the first base substrate; bonding the electrically
insulating cover to the first base substrate comprises bonding the
electrically insulating cover to the first surface of the first
base substrate over the plurality of electrical connections; and
bonding the cap to the first base substrate comprises bonding the
cap to the first surface of the base substrate and bonding the cap
to the electrically insulating cover, the method further
comprising: bonding a plurality of electrical contacts to the first
base substrate, each electrical contact coupled to a respective one
of the plurality of electrical connections; and providing a
coupling between the at least one laser diode driver circuit and
the plurality of electrical contacts, in operation the at least one
laser diode driver circuit selectively drives current to the laser
diodes via the plurality of electrical contacts and the plurality
of electrical connections.
Description
BACKGROUND
Technical Field
[0001] The present disclosure is generally directed to systems,
devices, and methods relating to optical engines, for example,
optical engines for laser projectors used in wearable heads-up
displays or other applications.
Description of the Related Art
[0002] A projector is an optical device that projects or shines a
pattern of light onto another object (e.g., onto a surface of
another object, such as onto a projection screen) in order to
display an image or video on that other object. A projector
necessarily includes a light source, and a laser projector is a
projector for which the light source comprises at least one laser.
The at least one laser is temporally modulated to provide a pattern
of laser light and usually at least one controllable mirror is used
to spatially distribute the modulated pattern of laser light over a
two-dimensional area of another object. The spatial distribution of
the modulated pattern of laser light produces an image at or on the
other object. In conventional scanning laser projectors, at least
one controllable mirror may be used to control the spatial
distribution, and may include: a single digital micromirror (e.g.,
a microelectromechanical system ("MEMS") based digital micromirror)
that is controllably rotatable or deformable in two dimensions, or
two digital micromirrors that are each controllably rotatable or
deformable about a respective dimension, or a digital light
processing ("DLP") chip comprising an array of digital
micromirrors.
[0003] In a conventional laser projector comprising an RGB
(red/green/blue) laser module with a red laser diode, a green laser
diode, and a blue laser diode, each respective laser diode may have
a corresponding respective focusing lens. Each of the laser diodes
of a laser module are typically housed in a separate package (e.g.,
a TO-38 package or "can"). The relative positions of the laser
diodes, the focusing lenses, and the at least one controllable
mirror are all tuned and aligned so that each laser beam impinges
on the at least one controllable mirror with substantially the same
spot size and with substantially the same rate of convergence (so
that all laser beams will continue to have substantially the same
spot size as they propagate away from the laser projector towards,
e.g., a projection screen). In a conventional laser projector, it
is usually possible to come up with such a configuration for all
these elements because the overall form factor of the device is not
a primary design consideration. However, in applications for which
the form factor of the laser projector is an important design
element, it can be very challenging to find a configuration for the
laser diodes, the focusing lenses, and the at least one
controllable mirror that sufficiently aligns the laser beams (at
least in terms of spot size, spot position, and rate of
convergence) while satisfying the form factor constraints.
[0004] A head-mounted display is an electronic device that is worn
on a user's head and, when so worn, secures at least one electronic
display within a viewable field of at least one of the user's eyes,
regardless of the position or orientation of the user's head. A
wearable heads-up display is a head-mounted display that enables
the user to see displayed content but also does not prevent the
user from being able to see their external environment. The
"display" component of a wearable heads-up display is either
transparent or at a periphery of the user's field of view so that
it does not completely block the user from being able to see their
external environment. A "combiner" component of a wearable heads-up
display is the physical structure where display light and
environmental light merge as one within the user's field of view.
The combiner of a wearable heads-up display is typically
transparent to environmental light but includes some optical
routing mechanism to direct display light into the user's field of
view.
[0005] Examples of wearable heads-up displays include: the Google
Glass.RTM., the Optinvent Ora.RTM., the Epson Moverio.RTM., and the
Sony Glasstron.RTM., just to name a few.
[0006] The optical performance of a wearable heads-up display is an
important factor in its design. When it comes to face-worn devices,
users also care a lot about aesthetics and comfort. This is clearly
highlighted by the immensity of the eyeglass (including sunglass)
frame industry. Independent of their performance limitations, many
of the aforementioned examples of wearable heads-up displays have
struggled to find traction in consumer markets because, at least in
part, they lack fashion appeal or comfort. Most wearable heads-up
displays presented to date employ relatively large components and,
as a result, are considerably bulkier, less comfortable and less
stylish than conventional eyeglass frames.
BRIEF SUMMARY
[0007] A method of manufacturing an optical engine may be
summarized as including: bonding a plurality of chip submounts to a
base substrate, each of the chip submounts including a laser diode
bonded thereto; and bonding a cap comprising at least one wall and
at least one optical window to the base substrate, the at least one
wall, the at least one optical window, and at least a portion of
the base substrate together delimit an interior volume sized and
dimensioned to receive at least the plurality of chip submounts and
laser diodes bonded to the plurality of chip submounts, the bonding
of the cap to the base substrate providing a hermetic or partially
hermetic seal between the interior volume of the cap and a volume
exterior to the cap, and the optical window positioned and oriented
to allow light emitted from the laser diodes to exit the interior
volume.
[0008] The method of manufacturing an optical engine may further
include bonding at least one of the laser diodes to a corresponding
one of the plurality of chip submounts.
[0009] Bonding at least one of the laser diodes to a corresponding
one of the plurality of chip submounts may include bonding at least
one of the laser diodes to a corresponding one of the plurality of
chip submounts using a eutectic gold tin (AuSn) solder process.
[0010] The method of manufacturing an optical engine may further
include: positioning a plurality of collimation lenses to be
adjacent the at least one optical window, each of the plurality of
collimation lenses positioned and oriented to receive light from a
corresponding one of the laser diodes through the at least one
optical window; and actively aligning each of the plurality of
collimation lenses.
[0011] The method of manufacturing an optical engine may further
include subsequent to actively aligning each of the plurality of
collimation lenses, bonding each of the collimation lenses to the
at least one optical window.
[0012] Actively aligning each of the plurality of collimation
lenses may include positioning each of the collimation lenses to
optimize spot and pointing for each of the respective laser
diodes.
[0013] The method of manufacturing an optical engine may further
include positioning a beam combiner to combine light beams received
from each of the collimation lenses into a single aggregate
beam.
[0014] The method of manufacturing an optical engine may further
include, prior to bonding the cap to the base substrate, bonding an
optical director element to the base substrate proximate the laser
diodes, the optical director element positioned and oriented to
direct laser light from the laser diodes toward the optical window
of the cap.
[0015] Bonding an optical director element may include bonding one
of a mirror or prism to the base substrate proximate the laser
diodes. Bonding an optical director element may include bonding an
optical director element to a base substrate using at least one of
a reflow oven process, thermosonic bonding, thermocompression
bonding, transient liquid phase (TLP) bonding, or laser
soldering.
[0016] The method of manufacturing an optical engine may further
include providing a coupling between at least one laser diode
driver circuit and the laser diodes, in operation the at least one
laser diode driver circuit selectively driving current to the laser
diodes.
[0017] The method of manufacturing an optical engine may further
include: bonding at least one laser diode driver circuit to the
base substrate; and providing a coupling between the at least one
laser diode driver circuit and the laser diodes, in operation the
at least one laser diode driver circuit selectively driving current
to the laser diodes.
[0018] Bonding the at least one laser diode driver circuit to the
base substrate may include bonding the at least one laser diode
driver circuit to a first surface of the base substrate, and
bonding the cap to the base substrate may include bonding the cap
to a second surface of the base substrate, the second surface of
the base substrate opposite the first surface of the base
substrate. Bonding the at least one laser diode driver circuit to
the base substrate may include bonding the at least one laser diode
driver circuit to a first surface of the base substrate, and
bonding the cap to the base substrate may include bonding the cap
to the first surface of the base substrate.
[0019] The method of manufacturing an optical engine may further
include providing the base substrate, wherein the base substrate is
formed from one of low temperature co-fired ceramic or alumina.
[0020] Bonding a plurality of chip submounts to a base substrate
may include step-soldering a plurality of chip submounts to a base
substrate. Bonding a plurality of chip submounts to a base
substrate may include bonding a plurality of chip submounts to a
base substrate using at least one of a reflow oven process,
thermosonic bonding, thermocompression bonding, transient liquid
phase (TLP) bonding, or laser soldering. Bonding a cap to the base
substrate may include bonding a cap to the base substrate using at
least one of a seam welding process, a laser assisted soldering
process, or a diffusion bonding process.
[0021] The method of manufacturing an optical engine may further
include, prior to bonding the cap to the base substrate, flooding
the interior volume with an oxygen rich atmosphere.
[0022] Bonding a plurality of chip submounts to a base substrate
may include bonding a chip submount that has a red laser diode
bonded thereto, bonding a chip submount that has a green laser
diode bonded thereto, bonding a chip submount that has a blue laser
diode bonded thereto, and bonding a chip submount that has an
infrared laser diode bonded thereto. Bonding a plurality of chip
submounts to a base substrate may include soldering a plurality of
chip submounts to a base substrate using a reactive multi-layer
foil material preform.
[0023] A method of manufacturing an optical engine may be
summarized as including: bonding a plurality of laser diodes
directly or indirectly to a base substrate; and bonding a cap
comprising at least one wall and at least one optical window to the
base substrate, the at least one wall, the at least one optical
window, and at least a portion of the base substrate together
delimit an interior volume sized and dimensioned to receive at
least the plurality of laser diodes bonded to the base substrate,
the bonding of the cap to the base substrate providing a hermetic
or partially hermetic seal between the interior volume of the cap
and a volume exterior to the cap, and the optical window positioned
and oriented to allow light emitted from the laser diodes to exit
the interior volume.
[0024] The method of manufacturing an optical engine may further
include bonding at least one of the laser diodes indirectly to the
base substrate by bonding the at least one laser diode to a
respective chip submount; and bonding the chip submount to the base
substrate.
[0025] The method of manufacturing an optical engine may further
include bonding each of the laser diodes indirectly to the base
substrate by bonding each laser diode to a respective chip
submount; and bonding each chip submount to the base substrate.
Bonding each laser diode to a respective chip submount may include
bonding each laser diode to a respective chip submount using a
eutectic gold tin (AuSn) solder process. Bonding each chip submount
to the base substrate may include step-soldering each chip submount
to the base substrate. Bonding each chip submount to the base
substrate may include bonding each chip submount to the base
substrate using at least one of a reflow oven process, thermosonic
bonding, thermocompression bonding, transient liquid phase (TLP)
bonding, or laser soldering. Bonding each chip submount to the base
substrate may include bonding a chip submount that has a red laser
diode bonded thereto, bonding a chip submount that has a green
laser diode bonded thereto, bonding a chip submount that has a blue
laser diode bonded thereto, and bonding a chip submount that has an
infrared laser diode bonded thereto. Bonding each chip submount to
the base substrate may include soldering each chip submount to the
base substrate using a reactive multi-layer foil material
preform.
[0026] The method of manufacturing an optical engine may further
include positioning a plurality of collimation lenses to be
adjacent the at least one optical window, each of the plurality of
collimation lenses positioned and oriented to receive light from a
corresponding one of the laser diodes through the at least one
optical window; and actively aligning each of the plurality of
collimation lenses. The method of manufacturing an optical engine
may further include, subsequent to actively aligning each of the
plurality of collimation lenses, bonding each of the collimation
lenses to the at least one optical window. Actively aligning each
of the plurality of collimation lenses may include positioning each
of the collimation lenses to optimize spot and pointing for each of
the respective laser diodes. The method of manufacturing an optical
engine may further include positioning a beam combiner to combine
light beams received from each of the collimation lenses into a
single aggregate beam.
[0027] The method of manufacturing an optical engine may further
include, prior to bonding the cap to the base substrate, bonding an
optical director element to the base substrate proximate the laser
diodes, the optical director element positioned and oriented to
direct laser light from the laser diodes toward the optical window
of the cap. Bonding an optical director element may include bonding
one of a mirror or prism to the base substrate proximate the laser
diodes. Bonding an optical director element may include bonding an
optical director element to a base substrate using at least one of
a reflow oven process, thermosonic bonding, thermocompression
bonding, transient liquid phase (TLP) bonding, or laser
soldering.
[0028] The method of manufacturing an optical engine may further
include providing a coupling between at least one laser diode
driver circuit and the laser diodes, in operation the at least one
laser diode driver circuit selectively driving current to the laser
diodes.
[0029] The method of manufacturing an optical engine may further
include: bonding at least one laser diode driver circuit to the
base substrate; and providing a coupling between the at least one
laser diode driver circuit and the laser diodes, in operation the
at least one laser diode driver circuit selectively driving current
to the laser diodes.
[0030] The method of manufacturing an optical engine may further
include providing the base substrate, wherein the base substrate is
formed from one of low temperature co-fired ceramic, aluminum
nitride (AlN), Kovar.RTM., or alumina.
[0031] Bonding a cap to the base substrate may include bonding a
cap to the base substrate using at least one of a seam welding
process, a laser assisted soldering process, or a diffusion bonding
process.
[0032] The method of manufacturing an optical engine may further
include, prior to bonding the cap to the base substrate, flooding
the interior volume with an oxygen rich atmosphere.
[0033] A method of manufacturing a laser projector may be
summarized as including: bonding a plurality of laser diodes
directly or indirectly to a first base substrate; providing a
coupling between at least one laser diode driver circuit and the
laser diodes, in operation the at least one laser diode driver
circuit selectively drives current to the laser diodes; bonding a
cap comprising at least one wall and at least one optical window to
the first base substrate, the at least one wall, the at least one
optical window, and at least a portion of the first base substrate
together delimit an interior volume sized and dimensioned to
receive at least the plurality of laser diodes bonded to the first
base substrate, the bonding of the cap to the first base substrate
providing a hermetic or partially hermetic seal between the
interior volume of the cap and a volume exterior to the cap, and
the optical window positioned and oriented to allow light emitted
from the laser diodes to exit the interior volume; bonding a
plurality of collimation lenses to be adjacent the at least one
optical window, each of the plurality of collimation lenses
positioned and oriented to receive light from a corresponding one
of the laser diodes through the at least one optical window;
positioning a beam combiner to combine light beams received from
each of the collimation lenses into a single aggregate beam; and
positioning at least one scan mirror to receive laser light from
the plurality of laser diodes, the at least one scan mirror
controllably orientable to redirect the laser light over a range of
angles.
[0034] The method of manufacturing a laser projector may further
include bonding at least one of the laser diodes indirectly to the
first base substrate by bonding the at least one laser diode to a
respective chip submount; and bonding the chip submount to the
first base substrate.
[0035] The method of manufacturing a laser projector may further
include bonding each of the laser diodes indirectly to the first
base substrate by bonding each laser diode to a respective chip
submount; and bonding each chip submount to the first base
substrate. Bonding each laser diode to a respective chip submount
may include bonding each laser diode to a respective chip submount
using a eutectic gold tin (AuSn) solder process. Bonding each chip
submount to the first base substrate may include step-soldering
each chip submount to the first base substrate. Bonding each chip
submount to the first base substrate may include bonding each chip
submount to the first base substrate using at least one of a reflow
oven process, thermosonic bonding, thermocompression bonding,
transient liquid phase (TLP) bonding, or laser soldering. Bonding
each chip submount to the first base substrate may include bonding
a chip submount that has a red laser diode bonded thereto, bonding
a chip submount that has a green laser diode bonded thereto,
bonding a chip submount that has a blue laser diode bonded thereto,
and bonding a chip submount that has an infrared laser diode bonded
thereto. Bonding each chip submount to the first base substrate may
include soldering each chip submount to the first base substrate
using a reactive multi-layer foil material preform.
[0036] The method of manufacturing a laser projector may further
include, prior to bonding the plurality of collimation lenses,
actively aligning each of the plurality of collimation lenses.
Actively aligning each of the plurality of collimation lenses may
include positioning each of the collimation lenses to optimize spot
and pointing for each of the respective laser diodes.
[0037] The method of manufacturing a laser projector may further
include, prior to bonding the cap to the first base substrate,
bonding an optical director element to the first base substrate
proximate the laser diodes, the optical director element positioned
and oriented to direct laser light from the laser diodes toward the
optical window of the cap. Bonding an optical director element may
include bonding one of a mirror or prism to the first base
substrate proximate the laser diodes. Bonding an optical director
element may include bonding an optical director element to a first
base substrate using at least one of a reflow oven process,
thermosonic bonding, thermocompression bonding, transient liquid
phase (TLP) bonding, or laser soldering.
[0038] The method of manufacturing a laser projector may further
include bonding the at least one laser diode driver circuit to the
first base substrate.
[0039] The method of manufacturing a laser projector may further
include providing the first base substrate, wherein the first base
substrate is formed from one of low temperature co-fired ceramic,
aluminum nitride (AlN), Kovar.RTM., or alumina.
[0040] Bonding a cap to the first base substrate may include
bonding a cap to the first base substrate using at least one of a
seam welding process, a laser assisted soldering process, or a
diffusion bonding process.
[0041] The method of manufacturing a laser projector may further
include, prior to bonding the cap to the first base substrate,
flooding the interior volume with an oxygen rich atmosphere.
[0042] The method of manufacturing a laser projector may further
include bonding a plurality of electrical connections to the first
base substrate, each electrical connection coupled to a respective
laser diode in the plurality of laser diodes; bonding an
electrically insulating cover to the first base substrate over the
plurality of electrical connections; and providing a coupling
between the at least one laser diode driver circuit and the
plurality of electrical connections, in operation the at least one
laser diode driver circuit selectively drives current to the laser
diodes via the plurality of electrical connections.
[0043] The method of manufacturing a laser projector may further
include bonding the at least one laser diode driver circuit to a
first surface of the first base substrate, bonding the plurality of
electrical connections to the first base substrate may include
bonding the plurality of electrical connections to the first
surface of the first base substrate; and bonding the electrically
insulating cover to the first base substrate may include bonding
the electrically insulating cover to the first surface of the first
base substrate over the plurality of electrical connections; and
bonding the cap to the first base substrate may include bonding the
cap to the first surface of the base substrate and bonding the cap
to the electrically insulating cover.
[0044] Bonding the plurality of electrical connections to the first
base substrate may include bonding the plurality of electrical
connections to the first surface of the first base substrate;
bonding the electrically insulating cover to the first base
substrate may include bonding the electrically insulating cover to
the first surface of the first base substrate over the plurality of
electrical connections; and bonding the cap to the first base
substrate may include bonding the cap to the first surface of the
base substrate and bonding the cap to the electrically insulating
cover, and the method of manufacturing a laser projector may
further include bonding a plurality of electrical contacts to the
first base substrate, each electrical contact coupled to a
respective one of the plurality of electrical connections; and
providing a coupling between the at least one laser diode driver
circuit and the plurality of electrical contacts, in operation the
at least one laser diode driver circuit selectively drives current
to the laser diodes via the plurality of electrical contacts and
the plurality of electrical connections.
[0045] A method of manufacturing a wearable heads-up display (WHUD)
may be summarized as including: providing a support structure that
in use is worn on the head of a user; manufacturing a laser
projector by: bonding a plurality of laser diodes directly or
indirectly to a first base substrate; providing a coupling between
at least one laser diode driver circuit and the laser diodes, in
operation the at least one laser diode driver circuit selectively
drives current to the laser diodes; bonding a cap comprising at
least one wall and at least one optical window to the first base
substrate, the at least one wall, the at least one optical window,
and at least a portion of the first base substrate together delimit
an interior volume sized and dimensioned to receive at least the
plurality of laser diodes bonded to the first base substrate, the
bonding of the cap to the first base substrate providing a hermetic
or partially hermetic seal between the interior volume of the cap
and a volume exterior to the cap, and the optical window positioned
and oriented to allow light emitted from the laser diodes to exit
the interior volume; bonding a plurality of collimation lenses to
be adjacent the at least one optical window, each of the plurality
of collimation lenses positioned and oriented to receive light from
a corresponding one of the laser diodes through the at least one
optical window; positioning a beam combiner to combine light beams
received from each of the collimation lenses into a single
aggregate beam; and positioning at least one scan mirror to receive
laser light from the plurality of laser diodes, the at least one
scan mirror controllably orientable to redirect the laser light
over a range of angles; and coupling the laser projector to the
support structure.
[0046] The method of manufacturing a WHUD may further include
bonding at least one of the laser diodes indirectly to the first
base substrate by bonding the at least one laser diode to a
respective chip submount; and bonding the chip submount to the
first base substrate.
[0047] The method of manufacturing a WHUD may further include
bonding each of the laser diodes indirectly to the first base
substrate by bonding each laser diode to a respective chip
submount; and bonding each chip submount to the first base
substrate. Bonding each laser diode to a respective chip submount
may include bonding each laser diode to a respective chip submount
using a eutectic gold tin (AuSn) solder process. Bonding each chip
submount to the first base substrate may include step-soldering
each chip submount to the first base substrate. Bonding each chip
submount to the first base substrate may include bonding each chip
submount to the first base substrate using at least one of a reflow
oven process, thermosonic bonding, thermocompression bonding,
transient liquid phase (TLP) bonding, or laser soldering. Bonding
each chip submount to the first base substrate may include bonding
a chip submount that has a red laser diode bonded thereto, bonding
a chip submount that has a green laser diode bonded thereto,
bonding a chip submount that has a blue laser diode bonded thereto,
and bonding a chip submount that has an infrared laser diode bonded
thereto. Bonding each chip submount to the first base substrate may
include soldering each chip submount to the first base substrate
using a reactive multi-layer foil material preform.
[0048] The method of manufacturing a WHUD may further include,
prior to bonding the plurality of collimation lenses, actively
aligning each of the plurality of collimation lenses. Actively
aligning each of the plurality of collimation lenses may include
positioning each of the collimation lenses to optimize spot and
pointing for each of the respective laser diodes.
[0049] The method of manufacturing a WHUD may further include,
prior to bonding the cap to the first base substrate, bonding an
optical director element to the first base substrate proximate the
laser diodes, the optical director element positioned and oriented
to direct laser light from the laser diodes toward the optical
window of the cap. Bonding an optical director element may include
bonding one of a mirror or prism to the first base substrate
proximate the laser diodes. Bonding an optical director element may
include bonding an optical director element to a first base
substrate using at least one of a reflow oven process, thermosonic
bonding, thermocompression bonding, transient liquid phase (TLP)
bonding, or laser soldering.
[0050] The method of manufacturing a WHUD may further include
providing the first base substrate, wherein the first base
substrate is formed from one of low temperature co-fired ceramic,
aluminum nitride (AlN), Kovar.RTM., or alumina.
[0051] Bonding a cap to the first base substrate may include
bonding a cap to the first base substrate using at least one of a
seam welding process, a laser assisted soldering process, or a
diffusion bonding process.
[0052] The method of manufacturing a WHUD may further include,
prior to bonding the cap to the first base substrate, flooding the
interior volume with an oxygen rich atmosphere.
[0053] The method of manufacturing a WHUD may further include
bonding a plurality of electrical connections to the first base
substrate, each electrical connection coupled to a respective laser
diode in the plurality of laser diodes; bonding an electrically
insulating cover to the first base substrate over the plurality of
electrical connections; and providing a coupling between the at
least one laser diode driver circuit and the plurality of
electrical connections, in operation the at least one laser diode
driver circuit selectively drives current to the laser diodes via
the plurality of electrical connections.
[0054] The method of manufacturing a WHUD may further include
bonding the at least one laser diode driver circuit to a first
surface of the first base substrate, and bonding the plurality of
electrical connections to the first base substrate may include
bonding the plurality of electrical connections to the first
surface of the first base substrate; bonding the electrically
insulating cover to the first base substrate may include bonding
the electrically insulating cover to the first surface of the first
base substrate over the plurality of electrical connections; and
bonding the cap to the first base substrate may include bonding the
cap to the first surface of the base substrate and bonding the cap
to the electrically insulating cover.
[0055] Bonding the plurality of electrical connections to the first
base substrate may include bonding the plurality of electrical
connections to the first surface of the first base substrate;
bonding the electrically insulating cover to the first base
substrate may include bonding the electrically insulating cover to
the first surface of the first base substrate over the plurality of
electrical connections; and bonding the cap to the first base
substrate may include bonding the cap to the first surface of the
base substrate and bonding the cap to the electrically insulating
cover, and the method of manufacturing a WHUD may further include
bonding a plurality of electrical contacts to the first base
substrate, each electrical contact coupled to a respective one of
the plurality of electrical connections; and providing a coupling
between the at least one laser diode driver circuit and the
plurality of electrical contacts, in operation the at least one
laser diode driver circuit selectively drives current to the laser
diodes via the plurality of electrical contacts and the plurality
of electrical connections.
[0056] The method of manufacturing a WHUD may further include
bonding the at least one laser diode driver circuit to a second
base substrate.
[0057] The method of manufacturing a WHUD may further include
mounting the at least one laser diode driver circuit to the support
structure.
[0058] Bonding the cap to the first base substrate may include
bonding the cap to a first surface of the first base substrate, and
the method of manufacturing a WHUD may further include bonding the
at least one laser diode driver circuit to a second surface of the
base substrate, the second surface of the base substrate opposite
the first surface of the base substrate.
[0059] A method of manufacturing an optical engine may be
summarized as including: bonding a plurality of laser diodes
directly or indirectly to a first base substrate; bonding a
plurality of electrical connections to the first base substrate,
each electrical connection coupled to a respective laser diode in
the plurality of laser diodes; bonding an electrically insulating
cover to the first base substrate over the plurality of electrical
connections; and bonding a cap comprising at least one wall and at
least one optical window to the first base substrate and the
electrically insulating cover, wherein the at least one wall, the
at least one optical window, the electrically insulating cover, and
at least a portion of the first base substrate together delimit an
interior volume sized and dimensioned to receive at least the
plurality of laser diodes, the bonding of the cap to the first base
substrate and the electrically insulating cover providing a
hermetic or partially hermetic seal between the interior volume of
the cap and a volume exterior to the cap, and the optical window
positioned and oriented to allow light emitted from the laser
diodes to exit the interior volume.
[0060] The method of manufacturing an optical engine may further
include bonding at least one of the laser diodes indirectly to the
first base substrate by bonding the at least one laser diode to a
respective chip submount; and bonding the chip submount to the
first base substrate.
[0061] The method of manufacturing an optical engine may further
include bonding each of the laser diodes indirectly to the first
base substrate by bonding each laser diode to a respective chip
submount; and bonding each chip submount to the first base
substrate. Bonding each laser diode to a respective chip submount
may include bonding each laser diode to a respective chip submount
using a eutectic gold tin (AuSn) solder process. Bonding each chip
submount to the first base substrate may include step-soldering
each chip submount to the first base substrate. Bonding each chip
submount to the first base substrate may include bonding each chip
submount to the first base substrate using at least one of a reflow
oven process, thermosonic bonding, thermocompression bonding,
transient liquid phase (TLP) bonding, or laser soldering. Bonding
each chip submount to the first base substrate comprises bonding a
chip submount that has a red laser diode bonded thereto, bonding a
chip submount that has a green laser diode bonded thereto, bonding
a chip submount that has a blue laser diode bonded thereto, and
bonding a chip submount that has an infrared laser diode bonded
thereto. Bonding each chip submount to the first base substrate
comprises soldering each chip submount to the first base substrate
using a reactive multi-layer foil material preform.
[0062] The method of manufacturing an optical engine may further
include positioning a plurality of collimation lenses to be
adjacent the at least one optical window, each of the plurality of
collimation lenses positioned and oriented to receive light from a
corresponding one of the laser diodes through the at least one
optical window; and actively aligning each of the plurality of
collimation lenses. The method of manufacturing an optical engine
may further include, subsequent to actively aligning each of the
plurality of collimation lenses, bonding each of the collimation
lenses to the at least one optical window. Actively aligning each
of the plurality of collimation lenses may include positioning each
of the collimation lenses to optimize spot and pointing for each of
the respective laser diodes. The method of manufacturing an optical
engine may further include positioning a beam combiner to combine
light beams received from each of the collimation lenses into a
single aggregate beam.
[0063] The method of manufacturing an optical engine may further
include, prior to bonding the cap to the first base substrate and
electrically insulating cover, bonding an optical director element
to the first base substrate proximate the laser diodes, the optical
director element positioned and oriented to direct laser light from
the laser diodes toward the optical window of the cap. Bonding an
optical director element may include bonding one of a mirror or
prism to the first base substrate proximate the laser diodes.
Bonding an optical director element may include bonding an optical
director element to a first base substrate using at least one of a
reflow oven process, thermosonic bonding, thermocompression
bonding, transient liquid phase (TLP) bonding, or laser
soldering.
[0064] The method of manufacturing an optical engine may further
include providing a coupling between at least one laser diode
driver circuit and the plurality of electrical connections, in
operation the at least one laser diode driver circuit selectively
drives current to the laser diodes via the plurality of electrical
connections.
[0065] The method of manufacturing an optical engine may further
include bonding at least one laser diode driver circuit to the
first base substrate; and providing a coupling between the at least
one laser diode driver circuit and the plurality of electrical
connections, in operation the at least one laser diode driver
circuit selectively drives current to the laser diodes via the
plurality of electrical connections.
[0066] Bonding the at least one laser diode driver circuit to the
first base substrate may include bonding the at least one laser
diode driver circuit to a first surface of the first base
substrate; bonding the plurality of electrical connections to the
first base substrate may include bonding the plurality of
electrical connections to the first surface of the first base
substrate; bonding the electrically insulating cover to the first
base substrate may include bonding the electrically insulating
cover to the first surface of the first base substrate over the
plurality of electrical connections; and bonding the cap to the
first base substrate and the electrically insulating cover may
include bonding the cap to the first surface of the base substrate
and the electrically insulating cover.
[0067] The method of manufacturing an optical engine may further
include bonding a plurality of electrical contacts to the first
base substrate, each electrical contact coupled to a respective one
of the plurality of electrical connections. The method of
manufacturing an optical engine may further include bonding at
least one laser diode driver circuit to a second base substrate;
and providing a coupling between the at least one laser diode
driver circuit and the plurality of electrical contacts, in
operation the at least one laser diode driver circuit selectively
drives current to the laser diodes via the plurality of electrical
contacts and the plurality of electrical connections.
[0068] The method of manufacturing an optical engine may further
include providing the first base substrate, wherein the first base
substrate is formed from one of low temperature co-fired ceramic,
aluminum nitride (AlN), Kovar.RTM., or alumina.
[0069] Bonding a cap to the first base substrate and the
electrically insulating cover may include bonding a cap to the
first base substrate using at least one of a seam welding process,
a laser assisted soldering process, or a diffusion bonding
process.
[0070] The method of manufacturing an optical engine may further
include, prior to bonding the cap to the first base substrate and
the electrically insulating cover, flooding the interior volume
with an oxygen rich atmosphere.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0071] In the drawings, identical reference numbers identify
similar elements or acts. The sizes and relative positions of
elements in the drawings are not necessarily drawn to scale. For
example, the shapes of various elements and angles are not
necessarily drawn to scale, and some of these elements may be
arbitrarily enlarged and positioned to improve drawing legibility.
Further, the particular shapes of the elements as drawn, are not
necessarily intended to convey any information regarding the actual
shape of the particular elements, and may have been solely selected
for ease of recognition in the drawings.
[0072] FIG. 1A is a left side, sectional elevational view of an
optical engine, in accordance with the present systems, devices,
and methods.
[0073] FIG. 1B is a front side, sectional elevational view of the
optical engine also shown in FIG. 1A, in accordance with the
present systems, devices, and methods.
[0074] FIG. 2 is a flow diagram of a method of operating an optical
engine, in accordance with the present systems, devices, and
methods.
[0075] FIG. 3 is a schematic diagram of a wearable heads-up display
with a laser projector that includes an optical engine, and a
transparent combiner in a field of view of an eye of a user, in
accordance with the present systems, devices, and methods.
[0076] FIG. 4 is an isometric view of a wearable heads-up display
with a laser projector that includes an optical engine, in
accordance with the present systems, devices, and methods.
[0077] FIG. 5 is a flow diagram of a method of manufacturing an
optical engine, in accordance with the present systems, devices,
and methods.
[0078] FIGS. 6A and 6B are isometric views showing implementations
of optical engines having differing positions for a laser diode
driver circuit in accordance with the present systems, devices, and
methods.
[0079] FIG. 7 is an isometric view of a laser diode, showing a fast
axis and a slow axis of a light beam generated by the laser diode,
in accordance with the present systems, devices, and methods.
[0080] FIG. 8A is a side sectional view of a set of collimation
lenses for collimating a beam of light separately along different
axes.
[0081] FIG. 8B is a top sectional elevational view of the set of
collimation lenses of FIG. 8A.
[0082] FIGS. 8C and 8D are isometric views of exemplary lens shapes
which could be used as lenses in the implementation of FIGS. 8A and
8B.
[0083] FIG. 9A is a side sectional view of a set of collimation
lenses for circularizing and collimating a beam of light.
[0084] FIG. 9B is a top sectional elevational view of the set of
collimation lenses of FIG. 9A.
[0085] FIGS. 9C and 9D are isometric views of exemplary lens shapes
which could be used as a collimation lens in the implementation of
FIGS. 9A and 9B.
DETAILED DESCRIPTION
[0086] In the following description, certain specific details are
set forth in order to provide a thorough understanding of various
disclosed implementations. However, one skilled in the relevant art
will recognize that implementations may be practiced without one or
more of these specific details, or with other methods, components,
materials, etc. In other instances, well-known structures
associated with computer systems, server computers, and/or
communications networks have not been shown or described in detail
to avoid unnecessarily obscuring descriptions of the
implementations.
[0087] Unless the context requires otherwise, throughout the
specification and claims that follow, the word "comprising" is
synonymous with "including," and is inclusive or open-ended (i.e.,
does not exclude additional, unrecited elements or method
acts).
[0088] Reference throughout this specification to "one
implementation" or "an implementation" means that a particular
feature, structure or characteristic described in connection with
the implementation is included in at least one implementation.
Thus, the appearances of the phrases "in one implementation" or "in
an implementation" in various places throughout this specification
are not necessarily all referring to the same implementation.
Furthermore, the particular features, structures, or
characteristics may be combined in any suitable manner in one or
more implementations.
[0089] As used in this specification and the appended claims, the
singular forms "a," "an," and "the" include plural referents unless
the context clearly dictates otherwise. It should also be noted
that the term "or" is generally employed in its sense including
"and/or" unless the context clearly dictates otherwise.
[0090] The headings and Abstract of the Disclosure provided herein
are for convenience only and do not interpret the scope or meaning
of the implementations.
[0091] One or more implementations of the present disclosure
provide laser-based optical engines, for example, laser-based
optical engines for laser projectors used in wearable heads-up
displays or other applications. Generally, the optical engines
discussed herein integrate a plurality of laser dies or diodes
(e.g., 3 laser diodes, 4 laser diodes) within a single,
hermetically or partially hermetically sealed, encapsulated
package. Such optical engines may have various advantages over
existing designs including, for example, smaller volume, lower
weight, better manufacturability, lower cost, faster modulation
speed, etc. The material used for the optical engines discussed
herein may be any suitable materials, e.g., ceramics with
advantageous thermal properties, etc. As noted above, such features
are particularly advantages in various applications including
WHUDs.
[0092] FIG. 1A is a left side, elevational sectional view of an
optical engine 100, which may also be referred to as a "multi-laser
diode module" or an "RGB laser module," in accordance with the
present systems, devices, and methods. FIG. 1B is a front side,
elevational sectional view of the optical engine 100. The optical
engine 100 includes a base substrate 102 having a top surface 104
and a bottom surface 106 opposite the top surface. The base
substrate 102 may be formed from a material that is radio frequency
(RF) compatible and is suitable for hermetic sealing. For example,
the base substrate 102 may be formed from low temperature co-fired
ceramic (LTCC), aluminum nitride (AlN), alumina, Kovar.RTM., other
ceramics with suitable thermal properties, etc. The term Kovar.RTM.
generally refers to iron-nickel-cobalt alloys having similar
thermal expansion coefficients to glass and ceramics, thus making
Kovar.RTM. materials particularly suitable for forming hermetic
seals which remain functional in a wide range of temperatures.
[0093] The optical engine 100 also includes a plurality of chip
submounts 108a-108d (collectively 108) bonded (e.g., attached) to
the top surface 104 of the base substrate 102. The plurality of
chip submounts 108 are aligned in a row across a width of the
optical engine 100 between the left and right sides thereof. Each
of the plurality of chip submounts 108 includes a laser diode 110,
also referred to as a laser chip or laser die, bonded thereto. In
particular, an infrared chip submount 108a carries an infrared
laser diode 110a, a red chip submount 108b carries a red laser
diode 110b, a green chip submount 108c carries a green laser diode
110c, and a blue chip submount 108d carries a blue laser diode
110d. In operation, the infrared laser diode 110a provides infrared
laser light, the red laser diode 110b provides red laser light, the
green laser diode 110c provides green laser light, and the blue
laser diode 110d provides blue laser light. Each of the laser
diodes 110 may comprise one of an edge emitter laser or a
vertical-cavity surface-emitting laser (VCSEL), for example. Each
of the four laser diode/chip submount pairs may be referred to
collectively as a "laser chip on submount," or a laser CoS 112.
Thus, the optical engine 100 includes an infrared laser CoS 112a, a
red laser CoS 112b, a green laser CoS 112c, and a blue laser CoS
112d. In at least some implementations, one or more of the laser
diodes 110 may be bonded directly to the base substrate 102 without
use of a submount 108. It should be appreciated that although some
implementations discussed herein describe laser diodes as chips or
dies on submounts, other dies or types of devices, e.g., p-side
down devices, may be used as well.
[0094] The optical engine 100 also includes a laser diode driver
circuit 114 bonded to the bottom surface 106 of the base substrate
102. The laser diode driver circuit 114 is operatively coupled to
the plurality of laser diodes 110 via suitable electrical
connections 116 to selectively drive current to the plurality of
laser diodes. In at least some implementations, the laser diode
driver circuit 114 may be positioned relative to the CoSs 112 to
minimize the distance between the laser diode driver circuit 114
and the CoSs 112. Although not shown in FIGS. 1A and 1B, the laser
diode driver circuit 114 may be operatively coupleable to a
controller (e.g., microcontroller, microprocessor, ASIC) which
controls the operation of the laser diode driver circuit 114 to
selectively modulate laser light emitted by the laser diodes 110.
In at least some implementations, the laser diode driver circuit
114 may be bonded to another portion of the base substrate 102,
such as the top surface 104 of the base substrate. In at least some
implementations, the laser diode driver circuity 114 may be
remotely located and operatively coupled to the laser diodes 110.
In order to not require the use of impedance matched transmission
lines, the size scale may be small compared to a wavelength (e.g.,
lumped element regime), where the electrical characteristics are
described by (lumped) elements like resistance, inductance, and
capacitance.
[0095] Proximate the laser diodes 110 there is positioned an
optical director element 118. Like the chip submounts 108, the
optical director element 118 is bonded to the top surface 104 of
the base substrate 102. In the illustrated example, the optical
director element 118 has a triangular prism shape that includes a
plurality of planar faces. In particular the optical director
element 118 includes an angled front face 118a that extends along
the width of the optical engine 100, a rear face 118b, a bottom
face 118c that is bonded to the top surface 104 of the base
substrate 102, a left face 118d, and a right face 118e opposite the
left face. The optical director element 118 may comprise a mirror
or a prism, for example.
[0096] The optical engine 100 also includes a cap 120 that includes
a vertical sidewall 122 having a lower first end 124 and an upper
second end 126 opposite the first end. A flange 128 may be disposed
around a perimeter of the sidewall 122 adjacent the lower first end
124. Proximate the upper second end 126 of the sidewall 122 there
is a horizontal optical window 130 that forms the "top" of the cap
120. The sidewall 122 and the optical window 130 together define an
interior volume 132 sized and dimensioned to receive the plurality
of chip submounts 108, the plurality of laser diodes 110, and the
optical director element 118. The lower first end 124 and the
flange 128 of the cap 120 are bonded to the base substrate 102 to
provide a hermetic or partially hermetic seal between the interior
volume 132 of the cap and a volume 134 exterior to the cap.
[0097] As shown best in FIG. 1A, the optical director element 118
is positioned and oriented to direct (e.g., reflect) laser light
received from each of the plurality of laser diodes 108 upward (as
shown) toward the optical window 130 of the cap 120, wherein the
laser light exits the interior volume 132.
[0098] The cap 120 may have a round shape, rectangular shape, or
other shape. Thus, the vertical sidewall 122 may comprise a
continuously curved sidewall, a plurality (e.g., four) of adjacent
planar portions, etc. The optical window 130 may comprise an entire
top of the cap 120, or may comprise only a portion thereof. In at
least some implementations, the optical window 130 may be located
on the sidewall 122 rather than positioned as a top of the cap 120,
and the laser diodes 110 and/or the optical director element 118
may be positioned and oriented to direct the laser light from the
laser diodes toward the optical window on the sidewall 122. In at
least some implementations, the cap 120 may include a plurality of
optical windows instead of a single optical window.
[0099] The optical engine 100 also includes four
collimation/pointing lenses 136a-136d (collectively 136), one for
each of the four laser diodes 110a-110d, respectively, that are
bonded to a top surface 138 of the optical window 130. Each of the
plurality of collimation lenses 136 is positioned and oriented to
receive light from a corresponding one of the laser diodes 110
through the optical window 130. In particular, the collimation lens
136a receives light from the infrared laser diode 110a via the
optical director element 118 and the optical window 130, the
collimation lens 136b receives light from the red laser diode 110b
via the optical director element and the optical window, the
collimation lens 136c receives light from the green laser diode
110c via the optical director element and the optical window, and
the collimation lens 136d receives light from the blue laser diode
110d via the optical director element and the optical window.
[0100] Each of the collimation lenses 136 is operative to receive
laser light from a respective one of the laser diodes 110, and to
generate a single color beam. In particular, the collimation lens
136a receives infrared laser light from the infrared laser diode
110a and produces an infrared laser beam 138a, the collimation lens
136b receives red laser light from the red laser diode 110b and
produces a red laser beam 138b, the collimation lens 136c receives
green laser light from the green laser diode 110c and produces a
green laser beam 138c, and the collimation lens 136d receives blue
laser light from the blue laser diode 110d and produces a blue
laser beam 138d.
[0101] The optical engine 100 may also include, or may be
positioned proximate to, a beam combiner 140 that is positioned and
oriented to combine the light beams 138a-138d received from each of
the collimation lenses 136 into a single aggregate beam 142. As an
example, the beam combiner 140 may include one or more diffractive
optical elements (DOE) and/or refractive/reflective optical
elements that combine the different color beams 138a-138d in order
to achieve coaxial superposition. An example beam combiner is shown
in FIG. 3 and discussed below.
[0102] In at least some implementations, the laser CoSs 112, the
optical director element 118, and/or the collimation lenses 136 may
be positioned differently. As noted above, laser diode driver
circuit 114 may be mounted on the top surface 104 or the bottom
surface 106 of the base substrate 102, depending on the RF design
and other constraints (e.g., package size). In at least some
implementations, the optical engine 100 may not include the optical
director element 118, and the laser light may be directed from the
laser diodes 110 toward the collimation lenses 136 without
requiring an intermediate optical director element. Additionally,
in at least some implementations, one or more of the laser diodes
may be mounted directly on the base substrate 102 without use of a
submount.
[0103] For the sake of a controlled atmosphere inside the interior
volume 132, it may be desirable to have no organic compounds inside
the interior volume 132. In at least some implementations, the
components of the optical engine 100 may be bonded together using
no adhesives. In other implementations, a low amount of adhesives
may be used to bond at least one of the components, which may
reduce cost while providing a relatively low risk of organic
contamination for a determined lifetime (e.g., 2 or more years) of
the optical engine 100. The use of adhesives may result in a
partially hermetic seal, but this partially hermetic seal may be
acceptable in certain applications, as detailed below.
[0104] Generally, "hermetic" refers to a seal which is airtight,
that is, a seal which excludes the passage of air, oxygen, and
other gases. "Hermetic" within the present specification carries
this meaning. Further, "partially hermetic" as used herein refers
to a seal which limits, but does not necessarily completely
prevent, the passage of gases such as air. "Partially hermetic" as
used herein may alternatively be stated as "reduced hermiticity".
In the example above, adhesives may be used to bond components.
Such adhesives may result in a seal being not completely hermetic,
in that some amount of gasses may slowly leak through the adhesive.
However, such a seal can still be considered "partially hermetic"
or as having "reduced hermiticity", because the seal reduces the
flow of gasses therethrough.
[0105] In one example application, even in an environment with only
partial hermiticity, the life of laser diodes 110 and transparency
of optical window 130 may be maintained longer than the life of a
battery of a device, such that partial hermiticity may be
acceptable for the devices. In some cases, even protecting interior
volume 132 from particulate with a dust cover may be sufficient to
maintain laser diodes 110 and transparency of optical window 130
for the intended lifespan of the device. In some cases, laser
diodes 110 and transparency of optical window 130 may last for the
intended lifespan of the device even without a protective cover.
Various bonding processes (e.g., attaching processes) for the
optical engine 100 are discussed below with reference to FIG.
5.
[0106] FIG. 2 is a flow diagram of a method 200 of operating an
optical engine, in accordance with the present systems, devices,
and methods. The method 200 may be implemented using the optical
engine 100 of FIGS. 1A-1B, for example. It should be appreciated
that methods of operating optical engines according to the present
disclosure may include fewer or additional acts than set forth in
the method 200. Further, the acts discussed below may be performed
in an order different than the order presented herein.
[0107] At 202, at least one controller may cause a plurality of
laser diodes of an optical engine to generate laser light. As
discussed above, the plurality of laser diodes may be hermetically
or partially hermetically sealed in an encapsulated package. The
laser diodes may produce light sequentially and/or simultaneously
with each other. At 204, at least one optical director element may
receive the laser light from the laser diodes. The optical director
element may comprise a mirror or a prism, for example. As discussed
above, in at least some implementations the optical engine may be
designed such that laser light exits the optical engine without use
of an optical director element.
[0108] At 206, the at least one optical director element may direct
the received laser light toward an optical window of the
encapsulated package. For example, the optical director element may
reflect the received laser light toward the optical window of the
encapsulated package.
[0109] At 208, a plurality of collimation lenses may collimate the
laser light from the laser diodes that exits the encapsulated
package via the optical window to generate a plurality of
differently colored laser light beams. The collimation lenses may
be positioned inside or outside of the encapsulated package. As an
example, the collimation lenses may be physically coupled to the
optical window of the encapsulated package.
[0110] At 210, a beam combiner may combine the plurality of laser
light beams received from each of the collimation lenses into a
single aggregate beam. The beam combiner may include one or more
diffractive optical elements (DOE) that combine different color
beams in order to achieve coaxial superposition, for example. The
beam combiner may include one or more DOEs and/or one or more
refractive/reflective optical elements. An example beam combiner is
shown in FIG. 3 and discussed below.
[0111] FIG. 3 is a schematic diagram of a wearable heads-up display
(WHUD) 300 with an exemplary laser projector 302, and a transparent
combiner 304 in a field of view of an eye 306 of a user of the
WHUD, in accordance with the present systems, devices, and methods.
The WHUD 300 includes a support structure (not shown), with the
general shape and appearance of an eyeglasses frame, carrying an
eyeglass lens 308 with the transparent combiner 304, and the laser
projector 302.
[0112] The laser projector 302 comprises a controller or processor
310, an optical engine 312 comprising four laser diodes 314a, 314b,
314c, 314d (collectively 314) communicatively coupled to the
processor 310, a beam combiner 316, and a scan mirror 318. The
optical engine 312 may be similar or identical to the optical
engine 100 discussed above with reference to FIGS. 1A and 1B.
Generally, the term "processor" refers to hardware circuitry, and
may include any of microprocessors, microcontrollers, application
specific integrated circuits (ASICs), digital signal processors
(DSPs), programmable gate arrays (PGAs), and/or programmable logic
controllers (PLCs), or any other integrated or non-integrated
circuit.
[0113] During operation of the WHUD 300, the processor 310
modulates light output from the laser diodes 314, which includes a
first red laser diode 314a (R), a second green laser diode 314b
(G), a third blue laser diode 314c (B), and a fourth infrared laser
diode 314d (IR). The first laser diode 314a emits a first (e.g.,
red) light signal 320, the second laser diode 314b emits a second
(e.g., green) light signal 322, the third laser diode 314c emits a
third (e.g., blue) light signal 324, and the fourth laser diode
314d emits a fourth (e.g., infrared) light signal 326. All four of
light signals 320, 322, 324, and 326 enter or impinge on the beam
combiner 316. Beam combiner 316 could for example be based on any
of the beam combiners described in U.S. Provisional Patent
Application Ser. No. 62/438,725, U.S. Non-Provisional patent
application Ser. No. 15/848,265 (U.S. Publication Number
2018/0180885), U.S. Non-Provisional patent application Ser. No.
15/848,388 (U.S. Publication Number 2018/0180886), U.S. Provisional
Patent Application Ser. No. 62/450,218, U.S. Non-Provisional patent
application Ser. No. 15/852,188 (U.S. Publication Number
2018/0210215), U.S. Non-Provisional patent application Ser. No.
15/852,282, (U.S. Publication Number 2018/0210213), and/or U.S.
Non-Provisional patent application Ser. No. 15/852,205 (U.S.
Publication Number 2018/0210216).
[0114] In the illustrated example, the beam combiner 316 includes
optical elements 328, 330, 332, and 334. The first light signal 320
is emitted towards the first optical element 328 and reflected by
the first optical element 328 of the beam combiner 316 towards the
second optical element 330 of the beam combiner 316. The second
light signal 322 is also directed towards the second optical
element 330. The second optical element 330 is formed of a dichroic
material that is transmissive of the red wavelength of the first
light signal 320 and reflective of the green wavelength of the
second light signal 322. Therefore, the second optical element 330
transmits the first light signal 320 and reflects the second light
signal 322. The second optical element 330 combines the first light
signal 320 and the second light signal 322 into a single aggregate
beam (shown as separate beams for illustrative purposes) and routes
the aggregate beam towards the third optical element 332 of the
beam combiner 316.
[0115] The third light signal 324 is also routed towards the third
optical element 332. The third optical element 332 is formed of a
dichroic material that is transmissive of the wavelengths of light
(e.g., red and green) in the aggregate beam comprising the first
light signal 320 and the second light signal 322 and reflective of
the blue wavelength of the third light signal 324. Accordingly, the
third optical element 332 transmits the aggregate beam comprising
the first light signal 320 and the second light signal 322 and
reflects the third light signal 324. In this way, the third optical
element 332 adds the third light signal 324 to the aggregate beam
such that the aggregate beam comprises the light signals 320, 322,
and 324 (shown as separate beams for illustrative purposes) and
routes the aggregate beam towards the fourth optical element 334 in
the beam combiner 316.
[0116] The fourth light signal 326 is also routed towards the
fourth optical element 334. The fourth optical element 334 is
formed of a dichroic material that is transmissive of the visible
wavelengths of light (e.g., red, green, and blue) in the aggregate
beam comprising the first light signal 320, the second light signal
322, and the third light signal 324 and reflective of the infrared
wavelength of the fourth light signal 326. Accordingly, the fourth
optical element 334 transmits the aggregate beam comprising the
first light signal 320, the second light signal 322, and the third
light signal 324 and reflects the fourth light signal 326. In this
way, the fourth optical element 334 adds the fourth light signal
326 to the aggregate beam such that the aggregate beam 336
comprises portions of the light signals 320, 322, 324, and 326. The
fourth optical element 334 routes the aggregate beam 336 towards
the controllable scan mirror 318.
[0117] The scan mirror 318 is controllably orientable and scans
(e.g. raster scans) the beam 336 to the eye 306 of the user of the
WHUD 300. In particular, the controllable scan mirror 318 scans the
laser light onto the transparent combiner 304 carried by the
eyeglass lens 308. The scan mirror 318 may be a single bi-axial
scan mirror or two single-axis scan mirrors may be used to scan the
laser light onto the transparent combiner 304, for example. In at
least some implementations, the transparent combiner 304 may be a
holographic combiner with at least one holographic optical element.
The transparent combiner 304 redirects the laser light towards a
field of view of the eye 306 of the user. The laser light
redirected towards the eye 306 of the user may be collimated by the
transparent combiner 304, wherein the spot at the transparent
combiner 304 is approximately the same size and shape as the spot
at the eye 306 of the user. The laser light may be converged by the
eye 306 to a focal point at the retina of eye 306 and creates an
image that is focused. The visible light may create display content
in the field of view of the user, and the infrared light may
illuminate the eye 306 of the user for the purpose of eye
tracking.
[0118] FIG. 4 is a schematic diagram of a wearable heads-up display
(WHUD) 400 with a laser projector 402 in accordance with the
present systems, devices, and methods. WHUD 400 includes a support
structure 404 with the shape and appearance of a pair of eyeglasses
that in use is worn on the head of the user. The support structure
404 carries multiple components, including eyeglass lens 406, a
transparent combiner 408, the laser projector 402, and a controller
or processor 410. The laser projector 402 may be similar or
identical to the laser projector 302 of FIG. 3. For example, the
laser projector 402 may include an optical engine, such as the
optical engine 100 or the optical engine 312. The laser projector
402 may be communicatively coupled to the controller 410 (e.g.,
microprocessor) which controls the operation of the projector 402,
as discussed above. The controller 410 may include or may be
communicatively coupled to a non-transitory processor-readable
storage medium (e.g., memory circuits such as ROM, RAM, FLASH,
EEPROM, memory registers, magnetic disks, optical disks, other
storage), and the controller may execute data and/or instruction
from the non-transitory processor readable storage medium to
control the operation of the laser projector 402.
[0119] In operation of the WHUD 400, the controller 410 controls
the laser projector 402 to emit laser light. As discussed above
with reference to FIG. 3, the laser projector 402 generates and
directs an aggregate beam (e.g., aggregate beam 336 of FIG. 3)
toward the transparent combiner 408 via at least one controllable
mirror (not shown in FIG. 4). The aggregate beam is directed
towards a field of view of an eye of a user by the transparent
combiner 408. The transparent combiner 408 may collimate the
aggregate beam such that the spot of the laser light incident on
the eye of the user is at least approximately the same size and
shape as the spot at transparent combiner 408. The transparent
combiner 408 may be a holographic combiner that includes at least
one holographic optical element.
[0120] FIG. 5 is a flow diagram of a method 500 of manufacturing an
optical engine, in accordance with the present systems, devices,
and methods. The method 500 may be implemented to manufacture the
optical engine 100 of FIGS. 1A-1B or the optical engine 312 of FIG.
3, for example. It should be appreciated that methods of
manufacturing optical engines according to the present disclosure
may include fewer or additional acts than set forth in the method
500. Further, the acts discussed below may be performed in an order
different than the order presented herein.
[0121] At 502, a plurality of laser diodes may be bonded to a
respective plurality of submounts. In at least some
implementations, this method may be performed by an entity
different than that manufacturing the optical engine. For example,
in at least some implementations, one or more of the plurality of
laser diodes (e.g., green laser diode, blue laser diode) may be
purchased as already assembled laser CoSs. For ease of handling and
simplification of the overall process, in at least some
implementations it may be advantageous to also bond laser diodes
that cannot be procured on submounts to a submount as well. As a
non-limiting example, in at least some implementations, one or more
of the laser diodes may be bonded to a corresponding submount using
an eutectic gold tin (AuSn) solder process, which is flux-free and
requires heating up top 280.degree. C.
[0122] At 504, the plurality of CoSs may be bonded to a base
substrate. Alternatively, act 502 could be skipped for at least one
or all of the laser diodes, and act 504 could comprise bonding the
at least one or all of the laser diodes directly to the base
substrate, as shown in FIGS. 6A and 6B. The base substrate may be
formed from a material that is RF compatible and is suitable for
hermetic sealing. For example, the base substrate may be formed
from low temperature co-fired ceramic (LTCC), aluminum nitride
(AlN), alumina, Kovar.RTM., etc. Since several CoSs are bonded next
to each other on the same base substrate, it may be advantageous to
either "step-solder" them sequentially or to use a bonding
technique that does not rely on re-melting of solder materials. For
step-soldering, each subsequent soldering step utilizes a process
temperature that is less than the process temperatures of previous
solder steps to prevent re-melting of solder materials. It may also
be important that the laser diode-to-submount bonding does not
re-melt during bonding of the CoSs to the base substrate. Bonding
technologies other than step-soldering that may be used include
parallel soldering of all CoS in reflow oven process, thermosonic
or thermocompression bonding, transient liquid phase (TLP) bonding,
laser soldering, etc. Some of these example bonding technologies
are discussed below.
[0123] For parallel soldering of all CoSs in a reflow oven process,
appropriate tooling is required to assure proper bonding and
alignment during the process. An advantage of this process is the
parallel and hence time efficient bonding of all CoSs at once and
even many assemblies in parallel. A possible disadvantage of this
process is the potential loss of the alignment of components during
the reflow process. Generally, a soldering cycle ideally needs a
few minutes of dwell time. Preheating may be used to reduce the
soldering time, which requires a few minutes for such a process
depending on the thermal mass of the components being bonded. Thus,
a batch process may be used with regular soldering to reduce the
assembly costs with high throughput at the expense of alignment
tolerance.
[0124] For thermosonic or thermocompression bonding, thick gold
metallization may be used but no extra solder layer is required.
The temperatures for thermocompression bonding might be as high as
300 to 350.degree. C. to have a good bond with a good thermal
conductivity. Thermosonic bonding may be used to reduce the
pressure and temperature needed for bonding, which may be required
for at least some components that might not tolerate the
temperatures required for thermocompression bonding.
[0125] Transient liquid phase (TLP) bonding may also be used. There
are many different reaction couples that may be used, including
gold-tin, copper-tin, etc. With this method, a liquid phase is
formed during the bonding which will solidify at the same
temperature. The re-melting temperatures of the bond are much
higher than the soldering temperatures.
[0126] In at least some implementations, laser soldering may be
used to bond some or all of the components of the optical engine.
Generally, the thermal characteristic of the parts to be bonded may
be important when implementing a laser soldering process.
[0127] Subsequent reflows of solder are not recommended due to
liquid phase reaction or dissolution mechanisms which may reduce
the reliability of the joint. This could result in voiding at the
interface or a reduction in strength of the joint itself. In order
to mitigate potential reflow dissolution problems, other options
can be taken into consideration, which do not rely on extreme
heating of the device and can be favorable in terms of production
cost. For example, bonding of the base substrate with adhesives
(electrically conductive for common mass, or non-conductive for
floating) may be acceptable with respect to heat transfer and
out-gassing as discussed regarding partial hermetic sealing
above.
[0128] Further, in at least some implementations, a reactive
multi-layer foil material (e.g., NanoFoil.RTM.) or a similar
material may be used as a solder pre-form, which enables localized
heat transfer. A reactive multi-layer foil material is a metallic
material based on a plurality (e.g., hundreds, thousands) of
reactive foils (aluminum and nickel) that enables die-attach
soldering (e.g., silicon chip onto stainless steel part). In such
implementations, dedicated heat transfer support metallizations may
be deposited onto the two components being joined together. This
method may be more advantageous for CoS-to-base substrate mounting
compared to chip-to-submount bonding. Generally, bonding using
reactive multi-layer foil materials enables furnace-free,
low-temperature soldering of transparent or non-transparent
components, without reaching the bonding temperatures for solder
reflow processes. Reactive multi-layer foil materials can be
patterned with a ps-laser into exact preform shapes.
[0129] At 506, the optical director element may be bonded to the
base substrate proximate the laser CoSs. The optical director
element may be bonded to the base substrate using any suitable
bonding process, including the bonding processes discussed above
with reference to act 504.
[0130] At 508, the laser diode driver circuit may optionally be
bonded to the base substrate. As noted above, the laser diode
driver circuit may be bonded to the base substrate such that the
distance between the laser diode driver circuit and the laser CoSs
is minimized. This may also comprise positioning a plurality of
electrical connections which operatively couple the laser diode
driver circuit to the plurality of laser diodes as shown in FIGS.
6A and 6B. In alternative implementations, the laser diode driver
circuit may be bonded to a separate base substrate from the other
components mentioned above as shown in FIG. 6B. The process used to
bond the laser diode driver circuit to a base substrate may be any
suitable bonding process, such as bonding processes commonly used
to bond surface mount devices (SMD) to circuit boards. In other
alternative implementations, the laser diode driver circuit may be
mounted directly to a frame of a WHUD. For implementations where
the laser diode drive circuit is not bonded to the same base
substrate as the other components mentioned above, a plurality of
electrical contacts and electrical connections could be bonded to
the base substrate, each electrical connection operatively
connecting a respective electrical contact to a respective laser
diode. Subsequently, the at least one laser driver circuit could be
operatively coupled to the electrical contacts, which will then
electrically couple the laser diode drive circuit to the electrical
connections and consequently to the laser diodes. An exemplary
arrangement of electrical connections and electrical contacts is
discussed later with reference to FIG. 6B.
[0131] At 510, the cap may be bonded to the base substrate to form
a hermetic or partially hermetic seal as discussed above between
the interior volume of the encapsulated package and an exterior
environment. As noted above, it may be desirable to maintain a
specific atmosphere for the laser diode chips for reliability
reasons. In at least some implementations, adhesive sealing may be
undesirable because of the high permeability of gases. This is
especially the case for blue laser diodes, which emit blue laser
light that may bake contamination on facets and windows, thereby
reducing transparency of the optical window. However, as detailed
above regarding FIGS. 1A and 1B, partial hermeticity, a particulate
dust cover, or even no protective cover may be acceptable for
certain applications. In implementations where the cap would be
bonded over electrical connections which connect the at least one
laser diode driver circuit to the plurality of laser diodes, such
as when the at least one laser diode driver circuit is bonded to
the same side of a base substrate as the laser diodes, or when the
at least one laser diode driver circuit is coupled to electrical
contacts bonded to the same side of the base substrate as the laser
diodes, an electrically insulating cover can first be bonded to the
base substrate over the electrical connections. Subsequently, the
cap can be bonded at least partially to the electrically insulating
cover, and potentially to a portion of the base substrate if the
insulating cover does not fully encircle the intended interior
volume. In this way, at least a portion of the cap will be bonded
to the base substrate indirectly by being bonded to the
electrically insulating cover. In some implementations, the entire
cap could be bonded to the base substrate indirectly by being
bonded to an electrically insulating cover which encircles the
intended interior volume. Exemplary electrically insulating covers
are discussed later with reference to FIGS. 6A and 6B.
[0132] During the sealing process, the atmosphere may be defined by
flooding the package accordingly. For example, the interior volume
of the encapsulated package may be flooded with an oxygen enriched
atmosphere that burns off contaminants which tend to form on
interfaces where the laser beam is present. The sealing itself may
also be performed so as to prevent the exchange between the package
atmosphere and the environment. Due to limitations concerning the
allowed sealing temperature, e.g., the components inside the
package should not be influenced, in at least some implementations
seam welding or laser assisted soldering/diffusion bonding may be
used. In at least some implementations, localized sealing using a
combination of seam welding and laser soldering may be used.
[0133] At 512, the collimation lenses may be actively aligned. For
example, once the laser diode driver circuit has been bonded and
the cap has been sealed, the laser diodes can be turned on and the
collimations lenses for each laser diode can be actively aligned.
In at least some implementations, each of the collimation lenses
may be positioned to optimize spot as well as pointing for each of
the respective laser diodes.
[0134] At 514, the beam combiner may be positioned to receive and
combine individual laser beams into an aggregate beam. As discussed
above, the beam combiner may include one or more diffractive
optical elements and/or one or more refractive/reflective optical
elements that function to combine the different color beams into an
aggregate beam. The aggregate beam may be provided to other
components or modules, such as a scan mirror of a laser projector,
etc.
[0135] FIGS. 6A and 6B are isometric views showing implementations
of optical engines having differing positions for a laser diode
driver circuit. The implementations shown in FIGS. 6A and 6B are
similar in at least some respects to the implementation of FIGS. 1A
and 1B, and one skilled in the art will appreciate that the
description regarding FIGS. 1A and 1B is applicable to the
implementations of FIGS. 6A and 6B unless context clearly dictates
otherwise.
[0136] FIG. 6A shows an optical engine 600a which includes a base
substrate 602. The base substrate 602 may be formed from a material
that is radio frequency (RF) compatible and is suitable for
hermetic sealing. For example, the base substrate 602 may be formed
from low temperature co-fired ceramic (LTCC), aluminum nitride
(AlN), alumina, Kovar.RTM., etc.
[0137] The optical engine 600a also includes a plurality of laser
diodes aligned in a row across a width of the optical engine 600a,
including an infrared laser diode 610a, a red laser diode 610b, a
green laser diode 610c, and a blue laser diode 610d. In operation,
the infrared laser diode 610a provides infrared laser light, the
red laser diode 610b provides red laser light, the green laser
diode 610c provides green laser light, and the blue laser diode
610d provides blue laser light. Each of the laser diodes may
comprise one of an edge emitter laser or a vertical-cavity
surface-emitting laser (VCSEL), for example. In FIG. 6A, laser
diodes 610a, 610b, 610c, and 610d are shown as being bonded (e.g.,
attached) directly to base substrate 602, as described above with
regards to act 504 in FIG. 5, but one skilled in the art will
appreciate that laser diodes 610a, 610b, 610c, and 610d could each
be mounted on a respective submount, similar to as in FIGS. 1A and
1B.
[0138] The optical engine 600a also includes a laser diode driver
circuit 614 which can be bonded to the same surface of base
substrate 602 as the laser diodes 610a, 610b, 610c, 610d. In
alternative implementations, laser diode driver circuit 614 can be
bonded to a separate base substrate, such as in FIG. 6B discussed
later. The laser diode driver circuit 614 is operatively coupled to
the plurality of laser diodes 610a, 610b, 610c, and 610d via
respective electrical connections 616a, 616b, 616c, 616d to
selectively drive current to the plurality of laser diodes. In at
least some implementations, the laser diode driver circuit 614 may
be positioned relative to the laser diodes 610a, 610b, 610c, and
610d to minimize the distance between the laser diode driver
circuit 614 and the laser diodes. Although not shown in FIG. 6A,
the laser diode driver circuit 614 may be operatively coupleable to
a controller (e.g., microcontroller, microprocessor, ASIC) which
controls the operation of the laser diode driver circuit 614 to
selectively modulate laser light emitted by the laser diodes 610a,
610b, 610c, and 610d. In at least some implementations, the laser
diode driver circuit 614 may be bonded to another portion of the
base substrate 602, such as the bottom surface of the base
substrate 602. In at least some implementations, the laser diode
driver circuitry 614 may be remotely located and operatively
coupled to the laser diodes 610a, 610b, 610c, and 610d. In order to
not require the use of impedance matched transmission lines, the
size scale may be small compared to a wavelength (e.g., lumped
element regime), where the electrical characteristics are described
by (lumped) elements like resistance, inductance, and
capacitance.
[0139] Proximate the laser diodes 610a, 610b, 610c, and 610d there
is positioned an optical director element 618. Like the laser
diodes 610a, 610b, 610c, and 610d, the optical director element 618
is bonded to the top surface of the base substrate 602. The optical
director element 618 may be bonded proximate to or adjacent each of
the laser diodes 610a, 610b, 610c, and 610d. In the illustrated
example, the optical director element 618 has a triangular prism
shape that includes a plurality of planar faces, similar to optical
director element 118 in FIGS. 1A and 1B. The optical director
element 618 may comprise a mirror or a prism, for example.
[0140] The optical engine 600a also includes a cap 620 similar to
cap 120 in FIGS. 1A and 1B. For clarity, cap 620 is shown as being
transparent in FIG. 6A, though this is not necessarily the case,
and cap 620 can be formed of an opaque material. Cap 620 includes a
horizontal optical window 630 that forms the "top" of the cap 620.
Although optical window 630 in FIG. 6A is shown as comprising the
entire top of cap 620, in alternative implementations optical
window could comprise only a portion of the top of cap 620. Cap 620
including optical window 630 defines an interior volume sized and
dimensioned to receive the plurality of laser diodes 610a, 610b,
610c, 610d, and the optical director element 618. Cap 620 is bonded
to the base substrate 602 to provide a hermetic or partially
hermetic seal between the interior volume of the cap 620 and a
volume exterior to the cap 620.
[0141] The optical director element 618 is positioned and oriented
to direct (e.g., reflect) laser light received from each of the
plurality of laser diodes 610a, 610b, 610c, and 610d upward toward
the optical window 630 of the cap 620, wherein the laser light
exits the interior volume, similar to FIGS. 1A and 1B.
[0142] The cap 620 may have a round shape, rectangular shape, or
other shape, similarly to as described regarding FIGS. 1A and 1B
above. The optical window 630 may comprise an entire top of the cap
620, or may comprise only a portion thereof. In at least some
implementations, the optical window 630 may be located on a
sidewall of cap 620 rather than positioned as a top of the cap 620,
and the laser diodes 610a, 610b, 610c, 610d and/or the optical
director element 618 may be positioned and oriented to direct the
laser light from the laser diodes toward the optical window on the
sidewall. In at least some implementations, the laser diodes 610a,
610b, 610c, and 610d may be positioned and oriented to direct the
laser light from the laser diode toward the optical window on the
sidewall without optical director element 618. In at least some
implementations, the cap 620 may include a plurality of optical
windows instead of a single optical window.
[0143] The optical engine 600a can also include four
collimation/pointing lenses similarly to as discussed regarding
FIGS. 1A and 1B above. Each of the collimation lenses can be
operative to receive laser light from a respective one of the laser
diodes 610a, 610b, 610c, or 610d, and to generate a single color
beam.
[0144] The optical engine 600a may also include, or may be
positioned proximate to, a beam combiner that is positioned and
oriented to combine the light beams received from each of the
collimation lenses or laser diodes 610a, 610b, 610c, or 610d into a
single aggregate beam. As an example, the beam combiner may include
one or more diffractive optical elements (DOE) and/or one or more
refractive/reflective optical elements that combine the different
color beams in order to achieve coaxial superposition. An example
beam combiner is shown in FIG. 3 and discussed above.
[0145] In at least some implementations, the laser diodes 610a,
610b, 610c, 610d, the optical director element 618, and/or the
collimation lenses may be positioned differently. As noted above,
laser diode driver circuit 614 may be mounted on a top surface or a
bottom surface of the base substrate 602, depending on the RF
design and other constraints (e.g., package size). In at least some
implementations, the optical engine 600a may not include the
optical director element 618, and the laser light may be directed
from the laser diodes 610a, 610b, 610c, and 610d toward collimation
lenses without requiring an intermediate optical director element.
Additionally, in at least some implementations, one or more of the
laser diodes may be mounted directly on the base substrate 602 with
a submount.
[0146] Optical engine 600a in FIG. 6A also includes an electrically
insulating cover 640. In FIG. 6A, laser diodes 610a, 610b, 610c,
and 610d are each connected to laser diode driver circuitry 614 by
a respective electrical connection 616a, 616b, 616c, or 616d
positioned as described above with regards to act 508 in FIG. 5.
Electrical connections 616a, 616b, 616c, and 616d run across a
surface of the base substrate 602. As described above with regards
to act 510 in FIG. 5, electrically insulating cover 640 is placed,
adhered, formed, or otherwise positioned over electrical
connections 616a, 616b, 616c, and 616d, such that each of the
electrical connections 616a, 616b, 616c, and 616d run through
electrically insulating cover 640. Also as described above with
regards to act 510 in FIG. 5, cap 620 is placed, adhered, formed,
or otherwise positioned over electrically insulating cover 640,
such that cap 620 does not contact any of the electrical
connections 616a, 616b, 616c, or 616d. For clarity, cap 620 is
shown as being transparent in FIG. 6A, though this is not
necessarily the case, and cap 620 can be formed of an opaque
material. Electrically insulating cover 640 can be formed of a
material with low electrical permittivity such as a ceramic, such
that electrical signals which run through electrical connections
616a, 616b, 616c, and 616d do not run into or through electrically
insulating cover 640. In this way, electrical signals which run
through electrical connections 616a, 616b, 616c, and 616d can be
prevented from running into or through cap 620, which can be formed
of an electrically conductive material. Although FIG. 6A shows
electrically insulating cover 640 as extending along only part of a
side of cap 620, one skilled in the art will appreciate that
electrically insulating cover 640 can extend along an entire side
length of cap 620.
[0147] One skilled in the art will appreciate that the positions of
laser diode driver circuitry 614, electrical connections 616a,
616b, 616c, 616d, and electrically insulating cover 640 as shown in
FIG. 6A could also be applied in other implementations of the
subject systems, devices and methods. For example, in the
implementations of FIGS. 1A and 1B, laser diode driver circuitry
114 could be positioned on top surface 104 of base substrate 102,
and electrical connections 116 could run across top surface 104
under an electrically insulating cover, such that electrical
connections 116 do not contact any conductive portion of cap
120.
[0148] FIG. 6B is an isometric view an optical engine 600b similar
in at least some respects to optical engine 600a of FIG. 6A. One
skilled in the art will appreciate that the description of optical
engine 600a in FIG. 6A is applicable to optical engine 600b in FIG.
6B, unless context clearly dictates otherwise. The optical engine
600b includes a base substrate 603a. Similar to base substrate 602
in FIG. 6A, base substrate 603a may be formed from a material that
is radio frequency (RF) compatible and is suitable for hermetic
sealing. For example, the base substrate 603a may be formed from
low temperature co-fired ceramic (LTCC), alumina, Kovar.RTM.,
etc.
[0149] One difference between optical engine 600b in FIG. 6B and
optical engine 600a in FIG. 6A relates to what components are
bonded (e.g. attached) to base substrate 603a. In optical engine
600b, each of: laser diodes 610a, 610b, 610c, 610d; cap 620;
electrical connections 616a, 616b, 616c, 616d; and electrically
insulating cover 640 are bonded (e.g., attached) to base substrate
603a. However, laser diode driver circuit 614 is not necessarily
bonded directly to base substrate 603a. Instead, laser diode driver
circuit 614 could be bonded to a separate base substrate 603b.
Similar to base substrate 602 in FIG. 6A and base substrate 603a in
FIG. 6B, base substrate 603b may be formed from a material that is
radio frequency (RF) compatible and is suitable for hermetic
sealing. For example, the base substrate 603b may be formed from
low temperature co-fired ceramic (LTCC), alumina, Kovar.RTM., etc.
In an alternative implementation, laser diode drive circuit 614 may
not need to be bonded to a substrate at all, and could simply be
mounted directly within a frame of a WHUD.
[0150] For implementations where laser diode drive circuit 614 is
not bonded to base substrate 603a, electrical contacts 617a, 617b,
617c, and 617d could be bonded to base substrate 603a, each at an
end of a respective electrical connection 616a, 616b, 616c, or 616d
as described above with regards to act 508 in FIG. 5. In this way,
electrical contacts 617a, 617b, 617c, and 617d could be used to
electrically couple laser diode drive circuit 614 to electrical
connections 616a, 616b, 616c, and 616d and consequently laser
diodes 610a, 610b, 610c, and 610d.
[0151] Throughout this application, collimation lenses have been
represented in the Figures by a simple curved lens shape. However,
the subject systems, devices, and methods can utilize more advanced
collimation schemes, as appropriate for a given application.
[0152] FIG. 7 shows an exemplary situation where using an advanced
collimation scheme would be helpful. FIG. 7 is an isometric view of
a laser diode 700. The laser diode 700 may be similar or identical
to the various laser diodes discussed herein. The laser diode 700
outputs a laser light beam 702 via an output facet 704 of the laser
diode. FIG. 7 shows the divergence of the light 702 emitting from
the laser diode 700. As shown, the light beam 702 may diverge by a
substantial amount along a fast axis 706 (or perpendicular axis)
and by a lesser amount in the slow axis 708 (parallel axis). As a
non-limiting example, in at least some implementations, the light
beam 702 may diverge with full width half maximum (FWHM) angles of
up to 40 degrees in the fast axis direction 706 and up to 10
degrees in the slow axis direction 708. This divergence results in
a rapidly expanding elliptical cone.
[0153] FIGS. 8A and 8B show an exemplary collimation scheme that
can be used to circularize and collimate an elliptical beam such as
that shown in FIG. 7. FIG. 8A illustrates an orthogonal view of the
fast axis 706 of light beam 702 emitted from laser diode 700. FIG.
8B illustrates an orthogonal view of the slow axis 708 of light
beam 702 emitted from laser diode 700. As shown in FIG. 8A, a first
lens 800 collimates light beam 702 along fast axis 706. As shown in
FIG. 8B, first lens 800 is shaped so as to not substantially
influence light beam 702 along slow axis 708. Subsequently, as
shown in FIG. 8B, light beam 702 is collimated along slow axis 708
by a second lens 802. As shown in FIG. 8A, second lens 802 is
shaped so as to not substantially influence light beam 702 along
fast axis 706. In essence, light beam 702 is collimated along fast
axis 706 separately from slow axis 708. By collimating light beam
702 along fast axis 706 separately from slow axis 708, the
collimation power applied to each axis can be independently
controlled by controlling the power of lens 800 and lens 802
separately. Further, spacing between each of laser diode 700, lens
800, and lens 802 can be controlled to collimate light beam 702 to
a certain width in each axis separately. If light beam 702 is
collimated along fast axis 706 to the same width as slow axis 708,
light beam 702 can be circularized. Because light beam 702 will
typically diverge faster in the fast axis 706, it is generally
preferable to collimate light beam 702 along fast axis 706 first,
then collimate light beam 702 along slow axis 708 after. However,
it is possible in certain applications to collimate light beam 702
along slow axis 708 first, and subsequently collimate light beam
702 along fast axis 706 after. This can be achieved by reversing
the order of first lens 800 with second lens 802, with respect to
the path of travel of light beam 702.
[0154] FIGS. 8C and 8D are isometric views which illustrate
exemplary shapes for lenses 800 and 802. Each of lens 800 and 802
can be for example a half-cylinder as in FIG. 8C, a full cylinder
as in FIG. 8D, a quarter cylinder, a three-quarter cylinder, any
other partial cylinder, or any other appropriate shape. Lenses 800
and 802 can be similarly shaped, or can have different shapes.
[0155] FIGS. 9A and 9B illustrate an alternative collimation
scheme. FIG. 9A illustrates an orthogonal view of the fast axis 706
of light beam 702 emitted from laser diode 700. FIG. 9B illustrates
an orthogonal view of the slow axis 708 of light beam 702 emitted
from laser diode 700. As shown in FIG. 9A, a first lens 900
redirects light beam 702 along fast axis 706, to reduce divergence
of light beam 702 along fast axis 706. As shown in FIG. 9B, first
lens 900 is shaped so as to not substantially influence light beam
702 along slow axis 708. Preferably, first lens 900 will reduce
divergence of light beam 702 along fast axis 706 to match
divergence of light beam 702 along slow axis 708. That is, first
lens 900 preferably circularizes light beam 702. Subsequently, as
shown in FIGS. 9A and 9B, light beam 702 is collimated along both
fast axis 706 and slow axis 708 by a second lens 902. As shown in
FIGS. 9A and 9B, second lens 902 is shaped similarly with respect
to both the fast axis 706 and the slow axis 708, to evenly
collimate light beam 702. In essence, first lens 900 circularizes
light beam 702, and subsequently second lens 902 collimates light
beam 702 along both axes. First lens 900 can for example be shaped
similarly to lens 800 or lens 802 discussed above, and shown in
FIGS. 8C and 8D. Second lens 902 can for example be shaped as a
double convex lens as illustrated in FIG. 9C, or a single convex
lens (convex on either side) as illustrated in FIG. 9D, or any
other appropriate shape of collimating lens.
[0156] The collimation schemes illustrated in FIGS. 8A-8D and
9A-9D, and discussed above could be used in place of any of the
collimation lenses described herein, including at least collimation
lenses 136a, 136b, 136c, 136d.
[0157] A person of skill in the art will appreciate that the
teachings of the present systems, methods, and devices may be
modified and/or applied in additional applications beyond the
specific WHUD implementations described herein. In some
implementations, one or more optical fiber(s) may be used to guide
light signals along some of the paths illustrated herein.
[0158] The WHUDs described herein may include one or more sensor(s)
(e.g., microphone, camera, thermometer, compass, altimeter, and/or
others) for collecting data from the user's environment. For
example, one or more camera(s) may be used to provide feedback to
the processor of the WHUD and influence where on the display(s) any
given image should be displayed.
[0159] The WHUDs described herein may include one or more on-board
power sources (e.g., one or more battery(ies)), a wireless
transceiver for sending/receiving wireless communications, and/or a
tethered connector port for coupling to a computer and/or charging
the one or more on-board power source(s).
[0160] The above description of illustrated embodiments, including
what is described in the Abstract, is not intended to be exhaustive
or to limit the embodiments to the precise forms disclosed.
Although specific embodiments of and examples are described herein
for illustrative purposes, various equivalent modifications can be
made without departing from the spirit and scope of the disclosure,
as will be recognized by those skilled in the relevant art. The
teachings provided herein of the various embodiments can be applied
to other portable and/or wearable electronic devices, not
necessarily the exemplary wearable electronic devices generally
described above.
[0161] For instance, the foregoing detailed description has set
forth various embodiments of the devices and/or processes via the
use of block diagrams, schematics, and examples. Insofar as such
block diagrams, schematics, and examples contain one or more
functions and/or operations, it will be understood by those skilled
in the art that each function and/or operation within such block
diagrams, flowcharts, or examples can be implemented, individually
and/or collectively, by a wide range of hardware, software,
firmware, or virtually any combination thereof. In one embodiment,
the present subject matter may be implemented via Application
Specific Integrated Circuits (ASICs). However, those skilled in the
art will recognize that the embodiments disclosed herein, in whole
or in part, can be equivalently implemented in standard integrated
circuits, as one or more computer programs executed by one or more
computers (e.g., as one or more programs running on one or more
computer systems), as one or more programs executed by on one or
more controllers (e.g., microcontrollers) as one or more programs
executed by one or more processors (e.g., microprocessors, central
processing units, graphical processing units), as firmware, or as
virtually any combination thereof, and that designing the circuitry
and/or writing the code for the software and or firmware would be
well within the skill of one of ordinary skill in the art in light
of the teachings of this disclosure.
[0162] When logic is implemented as software and stored in memory,
logic or information can be stored on any processor-readable medium
for use by or in connection with any processor-related system or
method. In the context of this disclosure, a memory is a
processor-readable medium that is an electronic, magnetic, optical,
or other physical device or means that contains or stores a
computer and/or processor program. Logic and/or the information can
be embodied in any processor-readable medium for use by or in
connection with an instruction execution system, apparatus, or
device, such as a computer-based system, processor-containing
system, or other system that can fetch the instructions from the
instruction execution system, apparatus, or device and execute the
instructions associated with logic and/or information.
[0163] In the context of this specification, a "non-transitory
processor-readable medium" can be any element that can store the
program associated with logic and/or information for use by or in
connection with the instruction execution system, apparatus, and/or
device. The processor-readable medium can be, for example, but is
not limited to, an electronic, magnetic, optical, electromagnetic,
infrared, or semiconductor system, apparatus or device. More
specific examples (a non-exhaustive list) of the computer readable
medium would include the following: a portable computer diskette
(magnetic, compact flash card, secure digital, or the like), a
random access memory (RAM), a read-only memory (ROM), an erasable
programmable read-only memory (EPROM, EEPROM, or Flash memory), a
portable compact disc read-only memory (CDROM), digital tape, and
other non-transitory media.
[0164] The various embodiments described above can be combined to
provide further embodiments. To the extent that they are not
inconsistent with the specific teachings and definitions herein, at
least the following are incorporated herein by reference in their
entirety: U.S. Provisional Patent Application Ser. No. 62/438,725,
U.S. Non-Provisional patent application Ser. No. 15/848,265 (U.S.
Publication Number 2018/0180885), U.S. Non-Provisional patent
application Ser. No. 15/848,388 (U.S. Publication Number
2018/0180886), U.S. Provisional Patent Application Ser. No.
62/450,218, U.S. Non-Provisional patent application Ser. No.
15/852,188 (U.S. Publication Number 2018/0210215), U.S.
Non-Provisional patent application Ser. No 15/852,282, (U.S.
Publication Number 2018/0210213), U.S. Non-Provisional patent
application Ser. No. 15/852,205 (U.S. Publication Number
2018/0210216), U.S. Provisional Patent Application Ser. No.
62/575,677, U.S. Provisional Patent Application Ser. No.
62/591,550, U.S. Provisional Patent Application Ser. No.
62/597,294, U.S. Provisional Patent Application Ser. No.
62/608,749, U.S. Provisional Patent Application Ser. No.
62/609,870, U.S. Provisional Patent Application Ser. No.
62/591,030, U.S. Provisional Patent Application Ser. No.
62/620,600, U.S. Provisional Patent Application Ser. No.
62/576,962, U.S. Provisional Patent Application Ser. No.
62/760,835, U.S. Non-Provisional patent application Ser. No.
16/168,690, U.S. Non-Provisional patent application Ser. No.
16/171,206, and/or PCT Patent Application PCT/CA2018051344. Aspects
of the embodiments can be modified, if necessary, to employ
systems, circuits and concepts of the various patents, applications
and publications to provide yet further embodiments.
[0165] These and other changes can be made to the embodiments in
light of the above-detailed description. In general, in the
following claims, the terms used should not be construed to limit
the claims to the specific embodiments disclosed in the
specification and the claims, but should be construed to include
all possible embodiments along with the full scope of equivalents
to which such claims are entitled. Accordingly, the claims are not
limited by the disclosure.
* * * * *