U.S. patent application number 17/232696 was filed with the patent office on 2021-07-29 for manufacturing a graded index profile for waveguide display applications.
The applicant listed for this patent is Facebook Technologies, LLC. Invention is credited to Andrew John Ouderkirk.
Application Number | 20210231870 17/232696 |
Document ID | / |
Family ID | 1000005522950 |
Filed Date | 2021-07-29 |
United States Patent
Application |
20210231870 |
Kind Code |
A1 |
Ouderkirk; Andrew John |
July 29, 2021 |
MANUFACTURING A GRADED INDEX PROFILE FOR WAVEGUIDE DISPLAY
APPLICATIONS
Abstract
A manufacturing system for fabricating optical waveguides
includes a diffusion channel with a plurality of inlets at a first
end and an outlet at a second end opposite to the first end and
separated from the inlets by a channel length. Each of the
plurality of inlets includes a central inlet flowing a first resin
into the diffusion channel such that the first resin flows along
the channel length of the diffusion channel toward the outlet, and
an outer inlet flowing a second resin along a periphery of the
first resin. The second resin may have an index of refraction
different than the first resin. The diffusion may occur between
portions of the first resin and portions of the second resin over
the channel length to form a composite resin having a profile with
a plurality of indices of refraction in at least one dimension.
Inventors: |
Ouderkirk; Andrew John;
(Redmond, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Facebook Technologies, LLC |
Menlo Park |
CA |
US |
|
|
Family ID: |
1000005522950 |
Appl. No.: |
17/232696 |
Filed: |
April 16, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15695466 |
Sep 5, 2017 |
11009662 |
|
|
17232696 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 2006/12095
20130101; G02B 6/1342 20130101; G02B 6/122 20130101; G02B 6/138
20130101; B29D 11/00663 20130101; G02B 6/0065 20130101; G02B
6/12028 20130101; G02B 2006/1218 20130101; B29D 11/00682 20130101;
G02B 2006/12102 20130101 |
International
Class: |
G02B 6/134 20060101
G02B006/134; G02B 6/138 20060101 G02B006/138; B29D 11/00 20060101
B29D011/00; F21V 8/00 20060101 F21V008/00; G02B 6/12 20060101
G02B006/12; G02B 6/122 20060101 G02B006/122 |
Claims
1. A system comprising: a diffusion channel comprising a plurality
of inlets at a first end and an outlet at a second end opposite to
the first end and separated from the plurality inlets by a channel
length, the plurality of inlets comprising: a central inlet
configured to input a first resin into the diffusion channel such
that the first resin flows along the channel length of the
diffusion channel toward the outlet, and an outer inlet configured
to input a second resin along a periphery of the first resin, the
second resin having a refractive index different from a refractive
index of the first resin; wherein diffusion occurs between portions
of the first resin and portions of the second resin over the
channel length to form a composite resin having a substantially
graded refractive index profile with a refractive index spatially
varying along a thickness dimension of the composite resin.
2. The system of claim 1, further comprising: a diffusion system
for applying the composite resin onto a substrate; and a rotating
assembly configured to move the substrate along a length dimension
orthogonal to the thickness dimension.
3. The system of claim 1, further comprising an irradiation system
configured to cure at least a portion of the composite resin.
4. The system of claim 1, wherein the substantially graded
refractive index profile substantially does not vary along width
and length dimensions of the composite resin, wherein the width,
length, and thickness dimensions are orthogonal to one another.
5. The system of claim 1, wherein the spatially varying value of
the refractive index comprises a parabolic index profile.
6. The system of claim 1, wherein the first resin and the second
resin comprise at least one of polyacrylate, polyurethane,
polysilicone, polyester, polyolefin, polyamide, or
polycarbonate.
7. The system of claim 1, wherein the substantially graded
refractive index profile is achieved by selecting at least one of:
a flow rate of the first resin and the second resin; a time allowed
for the occurrence of diffusion; a proportion of the first resin
with respect to the second resin; or a gradient of temperature
across the diffusion channel.
8. The system of claim 1, wherein the substantially graded
refractive index profile is rotationally symmetric.
9. The system of claim 1, further comprising a second outer inlet
configured to input the second resin along the periphery of the
first resin.
10. The system of claim 1, wherein the diffusion channel is
substantially flat, and wherein the center inlet and the outer
inlet are disposed to provide the composite resin with the
refractive index varying along a thickness dimension of the
diffusion channel and not varying along a length and width
dimension of the diffusion channel.
11. A system comprising: a substantially flat diffusion channel
having mutually perpendicular thickness, length, and width
dimensions; a central inlet configured to input a first resin into
the diffusion channel for flowing the first resin in the diffusion
channel along the length dimension towards an outlet of the
diffusion channel; a first outer inlet configured to input a second
resin into the diffusion channel for co-flowing the second resin
with the first resin in the diffusion channel along its length
dimension towards the outlet; wherein diffusion occurs between
portions of the first and second resins as the first and second
resins co-flow in the diffusion channel, to form a composite resin
having a substantially graded refractive index profile with a
refractive index varying along the thickness dimension of the
diffusion channel.
12. The system of claim 11, further comprising a second outer inlet
disposed on an opposite side of the central inlet from the first
outer inlet, wherein the second outer inlet is configured to input
a third resin into the diffusion channel for co-flowing the third
resin with the first and second resins in the diffusion channel
along the length dimension towards the outlet.
13. The system of claim 12, wherein the second and third resins
comprise a same resin.
14. The system of claim 11, wherein the first resin and the second
resin comprise at least one of polyacrylate, polyurethane,
polysilicone, polyester, polyolefin, polyamide, or
polycarbonate.
15. The system of claim 11, wherein the substantially graded
refractive index profile is achieved by selecting at least one of:
a flow rate of the first resin and the second resin, a time allowed
for the occurrence of diffusion, a proportion of the first resin
with respect to the second resin, or a gradient of temperature
across the diffusion channel.
16. The system of claim 11, wherein the substantially graded
refractive index profile is symmetric.
17. The system of claim 11, further comprising a curing unit for
curing the composite resin by at least one of: heating the
composite resin; or irradiating the composite resin with an actinic
radiation.
18. A waveguide comprising: a solid composite resin waveguide body
comprising: a first surface; a second surface parallel to the first
surface; and a central layer in between the first surface and the
second surface; wherein the solid composite resin has a
substantially graded refractive index profile with a refractive
index varying along a first dimension orthogonal to the first and
second surfaces, wherein the refractive index is substantially not
varying along second and third dimensions parallel to the first and
second surfaces, wherein the first, second, and third dimensions
are orthogonal to each other; and wherein the solid composite resin
includes a cured inter-diffused mixture of first and second resins,
wherein a refractive index of the first resin is different from a
refractive index of the second resin.
19. The waveguide of claim 18, wherein the solid complex resin is
manufactured by a process comprising: flowing the first resin into
a central flat inlet of a plurality of inlets at a first end of the
diffusion channel-including an outlet at a second end opposite to
the first end and separated from the plurality of inlets by a
channel length; and flowing the second resin into an outer flat
inlet of the plurality of inlets along a periphery of the first
resin; wherein at least a portion of the second resin diffuses into
at least a portion of the first resin in the diffusion channel over
the channel length to form a mixture of the first resin and the
second resin.
20. The waveguide of claim 19, wherein the process further
comprises controlling at least one of: a first flow rate of the
first resin, a second flow rate of the second resin, a time allowed
for the diffusion, a proportion of the first resin to the second
resin, or a gradient of temperature across the diffusion channel.
Description
REFERENCE TO RELATED APPLICATION
[0001] The present invention is a continuation of U.S. patent
application Ser. No. 15/695,466 filed on Sep. 5, 2017 and
incorporated herein by reference in its entirety.
BACKGROUND
[0002] The present disclosure generally relates to waveguide
displays, and specifically to a method of manufacturing a planar
waveguide with a graded index profile in waveguide displays.
[0003] Graded index lenses (GRIN) create optical power within an
optical material. Such GRIN lenses are widely used for collimating
and imaging light in optical devices. Most GRIN lenses are in the
form of a round lens or fiber with a gradient in refractive index
present along two dimensions. Conventional GRIN lenses are
manufactured by processes such as ion exchange, chemical vapor
deposition, ion stuffing, partial polymerization, non-uniform
distribution of high index molecules in a polymer matrix, neutron
irradiation, and polymer layer coextrusion of polymers with a
relatively high and low index of refraction, etc. In such
processes, the GRIN lenses include layers that are significantly
thinner than the wavelength of light, and the effective refractive
index of the GRIN lenses is controlled by the ratio of the total
amount of high and low index polymers.
[0004] Unfortunately, current methods for making GRIN lenses have
several problems. For example, waveguides made by layer coextrusion
produces optics with much less scatter for light propagating at
near-normal angles to the surface of the waveguide, but can have
very high scatter for light propagating parallel to the surface of
the waveguide. Accordingly, conventional processes are not suitable
for making GRIN waveguides with better durability and
compactness.
SUMMARY
[0005] A system for fabricating optical waveguides includes a
diffusion channel with a plurality of inlets at a first end and an
outlet at a second end opposite to the first end and separated from
the plurality of inlets by a channel length. The plurality of
inlets includes a central inlet that flows a first resin into the
diffusion channel such that the first resin flows along the channel
length of the diffusion channel toward the outlet, and at least one
outer inlet that flows a second resin along a periphery of the
first resin. The second resin may have an index of refraction
different than the first resin. The diffusion may occur between
portions of the first resin and portions of the second resin over
the channel length to form a composite resin having a profile with
a plurality of indices of refractions in at least one dimension. In
one example, the plurality of indices of refraction in the profile
is achieved by at least one of: a flow rate of the first resin and
the second resin, a time allowed for the occurrence of diffusion, a
proportion of the first resin with respect to the second resin, a
gradient of temperature across the diffusion channel, and some
combination thereof. In some configurations, the composite resin
has a substantially parabolic profile with a plurality of index of
refractions along a first dimension and a fixed value of index of
refraction along a second dimension and a third dimension that are
orthogonal to the first dimension. The composite resin may form,
e.g., a waveguide having a graded index of refraction. The graded
index of refraction includes a plurality of indices of refraction
in at least one dimension. In some embodiments, the plurality of
indices of refraction may have a substantially parabolic
distribution.
[0006] In some embodiments, the system includes a diffusion system
that combine portions of the first resin and the second resin. The
diffusion system may apply the combined first resin and the second
resin onto a substrate. The system may also include a rotating
assembly that adjusts a portion of the substrate along a second
dimension orthogonal to the first dimension. The system may also
include an irradiation system that cures at least a portion of the
combined first resin and second resin.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a block diagram of a manufacturing system, in
accordance with one embodiment.
[0008] FIG. 2A illustrates an isometric view of a waveguide with
graded index profile, in accordance with an embodiment.
[0009] FIG. 2B illustrates a cross-sectional view of the waveguide
of FIG. 2A with graded index profile, in accordance with an
embodiment.
[0010] FIG. 3 illustrates an isometric view of a system for
manufacturing the waveguide of FIG. 2A, in accordance with an
embodiment.
[0011] FIG. 4A illustrates a cross-sectional view of a portion of
the system of FIG. 3 showing the diffusion of one or more resins,
in accordance with an embodiment.
[0012] FIG. 4B illustrates a cross-sectional view showing a
composite resin formed near an outlet of the system of FIG. 3, in
accordance with an embodiment.
[0013] FIG. 5 illustrates an isometric view of a system for
manufacturing the waveguide of FIG. 2A, in accordance with an
embodiment.
[0014] FIG. 6 is a flowchart illustrating a process performed by
the manufacturing system of FIG. 1, in accordance with one
embodiment.
[0015] The figures depict various embodiments of the present
invention for purposes of illustration only. One skilled in the art
will readily recognize from the following discussion that
alternative embodiments of the structures and methods illustrated
herein may be employed without departing from the principles of the
invention described herein.
DETAILED DESCRIPTION
Overview
[0016] A manufacturing system is described for manufacturing
optical waveguides with graded index profile having a substantially
parabolic profile with a plurality of index of refractions along a
first dimension and a fixed value of index of refraction along a
second dimension and a third dimension, where the second dimension
and the third dimension are orthogonal to the first dimension. In
some configurations, the plurality of index of refractions in the
profile is achieved by at least one of: a flow rate of a first
resin and a second resin, a time allowed for the occurrence of
diffusion of the first resin with the second resin, a proportion of
the first resin with respect to the second resin, a gradient of
temperature across the diffusion channel, and some combination
thereof.
[0017] In some embodiments, the index of refraction varies
according to the formula n=n.sub.0(1-AZ.sup.2/2), where A is a
positive coefficient, Z is the displacement from a mid-plane
between the front and back surface of the optical waveguide, n is
the refractive index along the direction of the displacement, and
n.sub.0 is the index of refraction at the mid-plane. The graded
index profile may be parabolic or hyperbolic. The graded index
profile may be symmetric from the mid-plane to the front and back
surfaces of the waveguide, or may have different profiles. For
example, the refractive index coefficient A may be different for
positive and negative values of `Z`. The mid-plane is generally
located at a mid-point between the front and back surfaces of the
optical waveguide, but may also be proximate to either the front
and/or back surfaces of the optical waveguide. The first resin and
the second resin are associated with a polydispersity index
determined by the ratio of the average molecular weight by weight
(M.sub.w) to the average molecular weight by number (M.sub.n) of
each resin. In some configurations, the average molecular weight by
weight and the average molecular weight by number are determined by
size exclusion chromatography. In a different configuration, an
image created by the optical waveguide has a modulation transfer
function (MTF) of at least 100 line pairs per millimeter (mm)
corresponding to a 50% contrast ratio of the image. In some
examples, the MTF of the optical waveguide ranges from 5 to 50
lines pairs per mm corresponding to the 50% contrast ratio of the
image.
[0018] FIG. 1 is a block diagram of a manufacturing system 100, in
accordance with one embodiment. The manufacturing system 100 is a
group of devices that produce an optical waveguide with a graded
index of refraction. The manufacturing system 100 includes a resin
flow system 110, a diffusion system 120, a curing system 130, or
some combination thereof. In some embodiments, the manufacturing
system 100 includes a controller (not shown here) that controls
each system in the manufacturing system 100.
[0019] The resin flow system 110 is a system that performs a flow
of a substance on a substrate creating a change in thickness of the
substrate. The resin flow system 110 includes a central inlet, one
or more outer inlets, a diffusion channel, and an outlet, as
described below in conjunction with FIG. 3. In one example, the
resin flow system 110 flows a first resin into the central inlet at
a first end of the diffusion channel with the outlet at a second
end separated from the inlets by a channel length. The resin flow
system 110 flows a second resin into the outer inlet along a
periphery of the first resin.
[0020] In some configurations, the resins entering the resin flow
system 110 may include a set of resins with a high refractive index
(e.g. above 1.5) and a low refractive index (e.g. below 1.5). The
desired refractive index profile of the optical waveguide may be
achieved by controlling flow rates, mixing of resins provided to
the resin flow system 110, time allowed for diffusion before
curing, and a gradient of temperature across the resin flow system
110. The flow rate and volume of the resin flow system 110
determines the residence time of the first resin. In some examples,
the average residence time of the first resin is in the range of 1
to 1000 seconds. In alternate examples, the average residence time
of the first resin is in the range of 1 and 20 seconds. In some
examples, the average temperature of the first resin is in the
range of 0 to 250.degree. C. In alternate examples, the average
temperature of the first resin is in the range of 20 to 100.degree.
C. In some configurations, the first resin may be heated to a
uniform temperature. In alternate configurations, the first resin
may have a temperature gradient. For example, one or more resins
may be heated to a plurality of temperatures before combining the
one or more resins in the resin flow system 110. The temperature of
the one or more resins may differ by 10, 20, 50, or more than
100.degree. C. In some applications, it may be desired to have the
majority of the diffusion occurring after the deposition of layers
of resin on a substrate, and before the resin is cured.
[0021] The diffusion system 120 is a system that performs a
diffusion of an additional material into a resin. In some
configurations, the additional material is one or more resins with
molecules that are responsible for the characteristic chemical
reactions of the resins. In one example, the diffusion system 120
performs a diffusion of portions of a first resin and a second
resin over a channel length to form a composite resin having a
profile with a plurality of index of refractions in at least one
dimension. For example, the channel length may range from about 1
to 100 cm, the channel width may range from about 1 to 100 cm, and
the channel height may range from about 0.1 to 10 cm.
[0022] The curing system 130 is a system that performs a curing of
a substrate to vary the index of refraction of the substrate. The
curing system 130 cures the substrate to stop the diffusion of one
or more additional layers formed on the substrate. In some
embodiments, the curing system 130 includes a convection oven, a
hotplate, a rapid thermal processing system, a UV irradiation
system, or some combination thereof. The diffusion furnace is a
furnace that drives the resins on the patterned substrate at a
range of temperatures and/or pressures in environments such as
vacuum, nitrogen, dry air, etc. In some embodiments, the curing
system 130 performs a heating process including, but not restricted
to, an adiabatic process, a thermal flux process, and an isothermal
process. The rapid thermal processing system is a single wafer hot
processing system that minimizes the thermal budget of a process by
reducing the time at a given temperature in addition to, or instead
of, reducing the temperature. The UV irradiation system is an
illumination system that illuminates ultra-violet radiation on the
resins to initiate curing.
[0023] In some configurations, the curing system 130 performs the
curing on one or more initiators in the resins through actinic
radiation (e.g. blue light, UV, or electron beams), thermal curing,
or some combination thereof. The resins may be cured through a
combination of, for example, thermally activated initiators in part
or all of the resins, and photoinitiated curing in part or all of
the resins. In some configurations, the curing system 130 may
partially cure the optical waveguide while traveling through the
resin flow system 110, and curing may be completed after the
partially cured waveguide exits the resin flow system 110. Such an
approach allows the curing system 130 to determine the shape of the
optical waveguide without the risk of the partially cured resin
sticking to the walls of the resin flow system 110.
[0024] In some embodiments, the manufacturing system 100 includes a
plurality of resin flow systems 110 and a controller (not shown
here) that controls each of the resin flow systems 110. For
example, the manufacturing system 100 includes a first resin flow
system 110 that flows a first resin at a first flow rate, and a
second resin flow system 110 that flows the first resin at a second
flow rate based on a processing instruction from the
controller.
[0025] FIG. 2A illustrates an isometric view of a waveguide 200
with graded index profile fabricated using the manufacturing system
100 of FIG. 1, in accordance with an embodiment. The waveguide 200
is an optical device that receives a beam of light at a first end
and transmits the received beam of light to a second end different
from the first end. For example, the optical device is an optical
waveguide, lens, mirror, etc. The waveguide 200 includes a front
surface 210, a back surface 220, a face 230A, and a face 230B. In
the embodiment of FIG. 2A, the waveguide 200 receives the ray 240
and the ray 250 at the face 230A and transmits the ray 260 and the
ray 270 from the face 230B.
[0026] As shown in FIG. 2A, the waveguide 200 has a substantially
parabolic index profile along the Z-dimension, and a fixed value of
index of refraction along the X-dimension and Y-dimension. In some
configurations, there may be some variation of index of refraction
along the X-dimension and Y-dimension. For example, the index of
refraction of the waveguide 200 may be modulated or formed into a
desired profile, depending on the application. In general, the
index of refraction of the waveguide 200 in both the X-dimension
and the Y-dimension may be constant for planes parallel to the
front surface 210, and the back surface 220. In one example, the
ratio of the length of the waveguide 200 along the Y-axis to the
thickness along the Z-axis, and the length of the waveguide 200
along the X-axis to the thickness along the Z-axis are both at
least 10. The waveguide 200 is made of polymers including, but not
restricted to, polyacrylate, polyurethane, polysilicone, polyester,
polyolefin, polyamide, polycarbonate, any other optically
transparent polymers and/or copolymers, and some combination
thereof. In one example, the waveguide 200 is made of a first resin
and a second resin associated with a polydispersity index of at
most 10.
[0027] In some embodiments, the waveguide 200 is a transparent,
planar waveguide having a graded index profile along the
Z-dimension with a variation of less than 0.1 per micron, and a
constant index of refraction along the X-dimension and the
Y-dimension. The waveguide 200 includes a central layer (not shown)
located at a midpoint between the front surface 210 and the back
surface 220, where the index of refraction of the central layer is
at least 0.01 higher than the index of refraction of areas adjacent
to the front surface 210 and the back surface 220. In some
configurations, an image created by the waveguide 200 has a
modulation transfer function of at least 100 line pairs per mm
corresponding to a 50% contrast ratio of the image.
[0028] FIG. 2B illustrates a cross-sectional view of the waveguide
200 with graded index profile fabricated using the manufacturing
system 100 of FIG. 1, in accordance with an embodiment. In the
embodiment of FIG. 2B, the waveguide 200 has a graded index of
refraction in the Z-dimension. The ray 240 and the ray 250
propagate through the waveguide 200, and are focused at the focal
point 265 and the focal point 275 as the rays 240 and 250 propagate
through the waveguide 200. The focal points 265 and 275 form images
of the rays 240 and 250, and allow a one-dimensional image of
sources to be relayed along the waveguide 200.
[0029] FIG. 3 illustrates an isometric view of a system 300 for
manufacturing the waveguide 200 of FIG. 2A, in accordance with an
embodiment. The system 300 includes a central inlet 310, an outer
inlet 320A, an outer inlet 320B, a channel 340, and an outlet 350.
In one example, the central inlet 310 flows a first resin (e.g.
methymethacrylate), and the outer inlet 320A and 320B flow a second
resin (e.g. hexafluorisopropylacrylate). The first and the second
resins are brought in contact with each other in region 330, and
may partially diffuse into each other along the channel 340. The
combination of the first resin and the second resin exit the system
300 at the outlet 350.
[0030] In alternate embodiments, the system 300 includes the
central inlet 310, and the outer inlet 320A. The central inlet 310
inputs the first resin into the channel 340 such that the first
resin flows along the channel length 360 of the channel 340 toward
the outlet 350. The outer inlet inputs a second resin along a
periphery of the first resin, where diffusion occurs between
portions of the first resin and portions of the second resin over
the channel length to form a composite resin having a profile with
a plurality of index of refractions in at least one dimension.
[0031] FIG. 4A illustrates a cross-sectional view of a portion 400
of the system 300 of FIG. 3 showing the diffusion of one or more
resins, in accordance with an embodiment. The portion 400 shows the
occurrence of diffusion in the system 300, where the first resin
420 mixes with the second resin 430A and 430B, come in contact in
the region 440, and show significant diffusion in the region 450.
The first resin 420 and the second resin 430A and 430B diffuse into
each other in the channel 340 and after being deposited on a
substrate, up to the point where each of the resins is cured. The
combination of diffusion occurring in the channel 340 and on the
substrate creates the desired refractive index profile. If a major
portion of a desired diffusion occurs in the channel 340,
preferably, the channel 340 is no wider than about 100 cm, more
preferably less than 10 cm, and most preferably less than about 1
cm. The average flow rates may be less than 100 cm/min, more
preferably less than 20 cm/min, and most preferably less than 10
cm/min.
[0032] FIG. 4B illustrates a cross-sectional view of a portion 405
of the system 300 of FIG. 3 with a composite resin 460 formed near
the outlet 350, in accordance with an embodiment. The portion 405
shows the occurrence of diffusion in the system 300, where the
channel 340 directs a composite resin 460 formed from portions of
the first resin 420, the second resin 430A, and the second resin
430B to the outlet 350. In some embodiments, the composite resin
460 may have gradient in the index profile that is substantially
curved (e.g., parabolic) from a mid-plane 470 located at a
mid-point between the front surface 210 and the back surface 220 of
the waveguide 200 of FIG. 2A. In alternate embodiments, the
composite resin 460 has a rotationally symmetrical profile with
reference to the Y-dimension. The refractive index of the composite
resin 460 will preferably have a refractive index of at least 1.55
in the center, and at most 1.50 at the sides.
[0033] FIG. 5 illustrates an isometric view of a system 500 for
manufacturing the waveguide 200 of FIG. 2A, in accordance with an
embodiment. The system 500 includes a resin flow system 510, a
substrate 520, a rotating assembly 530, and an irradiation system
540. The resin flow system 510 is an embodiment of the resin flow
system 110 of FIG. 1. The substrate 520 is a body that mounts the
waveguide 200 of FIG. 2A. For example, the substrate 520 can be a
thin layer of plastic sheet. Suitable substrates include, but are
not limited to, polyethylene terephthalate, polyethylene, and
polyimide. Substrate thickness is preferably between 10 and 100
microns. The rotating assembly 530 performs a rotation of the
substrate 520 about a first dimension (e.g., rotate around the
X-dimension) such that the substrate 520 moves along a second
dimension and a third dimension (e.g. Y-dimension and Z-dimension).
The irradiation system 540 is an illumination system that performs
a curing of at least a portion of a mixture of one or more resins.
Movement of the substrate 520 may be accomplished by other means as
well, including sliding the substrate 520 over the outlet of the
resin flow system 510, or using a translation stage. Alternately,
the resin may be allowed to flow out of the resin flow system 510
forming a freely suspended resin stream, the resins may then be
cured to form a waveguide.
[0034] In the embodiment of FIG. 5, the resin flow system 510
applies one or more resins to the substrate 520 supported by the
rotating assembly 530, and the resins flow from the resin flow
system 510 to the substrate 520 forming a region 550, where there
is little mixing in the transition. In some configurations, UV
light may be applied to a UV photoinitiated resin flow system 510
using one or more UV emitting lamps inside the irradiation system
540.
[0035] In some configurations, the irradiation system 540 cures the
resins through an actinic radiation (e.g. blue light, UV, or
electron beams), thermal curing, or a combination of both. The two
or more resins may use different initiation or curing approaches.
For example, one way of forming the substrate 520 is to use a
thermal initiator in the resins near the center of the resin flow
system 510, and a photoinitiator near or against the walls of the
resin flow system 510. The substrate 520 may be partially cured
while traveling through the resin flow system 510, and curing may
be completed after the partially cured substrate 520 exits the
outlet of the resin flow system 510. This approach allows the
curing system 130 of FIG. 1 to determine the shape of the substrate
520 without the risk of the partially cured resin sticking to the
walls of the resin flow system 510.
[0036] In some embodiments, the resins entering the resin flow
system 510 may be a set of resins with a range of refractive
indices. For example, if there are five inlets in the resin flow
system 510, with one of them being the center inlet (e.g. inlet 3),
two inlets (e.g. inlet 1 and 5) flowing the resins that form the
outermost surfaces of the waveguide 200, and the remaining two
inlets (e.g. inlet 2 and 4) may be provided with a mixture of
resins with a high and low index of refraction. High index resins
may have a refractive index of at least 1.55. Low index resins may
have a refractive index of at most 1.5. The desired refractive
index profile of the waveguide 200 may be achieved by controlling
process parameters, including, but not restricted to, flow rates,
mixing of resins provided to the resin flow system 510, time
allowed for diffusion before curing, and a gradient of temperature
across the resin flow system 510.
[0037] In an alternate embodiment, the substrate 520 supports at
least a first and a second polymer coextruded to form a stack of at
least three alternating layers of polymer sheets heated at or above
the glass transition temperature of the first and second polymer.
The stack of polymers may be allowed to diffuse into each other,
and the substrate 520 may be heated until the stack reaches the
desired refractive index profile. The first and second polymer may
have substantially similar solubility parameters. In some
configurations, the Relative Energy Difference (RED) of the resins
are at most 1, based on the Hansen solubility parameters.
[0038] In a different embodiment, a low molecular weight solvent or
plasticizer may be added to the first and second resin to promote
diffusion. For example, the stack of resins may be heated in the
presence of an organic or inorganic material that is absorbed into
the stack. The solvent or plasticizer may be removed from the stack
after the diffusion is complete. In one example, the first and
second polymer include polyacrylates (e.g. polymethylmethacrylate
and poly(2,2,2-trifluoroethyl methacrylate)), polyesters (e.g.
polyethylene terephthalate and poly(2,6-ethylene naphthalate),
isophthalate copolymers), and some other miscible polymer resins
from the families of polycarbonates, polysilicones, polyolefins,
polystyrenes, polyfluorocarbons, and some combination thereof. In
an alternate embodiment, different polymer sheets or films may be
stacked on each other and annealed by the curing system 130 of FIG.
1. In some configurations, one or more of the polymer layers may
contain a low molecular weight refractive index modifier that
diffuses through the polymer resins, and create the desired
refractive index profile.
[0039] FIG. 6 is a flowchart illustrating the process 600 performed
by the manufacturing system 100 of FIG. 1, in accordance with one
embodiment. The process 600 of FIG. 6 may be performed by the
manufacturing system 100. Other entities may perform some or all of
the steps of the process in other embodiments. Likewise,
embodiments may include different and/or additional steps, or
perform the steps in different orders.
[0040] As described above with reference to FIG. 1, the resin flow
system 110 flows 610 a first resin into a central inlet at a first
end of the diffusion channel with an outlet at a second end
separated from the inlets by a channel length. The resin flow
system 110 flows 620 a second resin into an outer inlet along a
periphery of the first resin. The diffusion system 120 performs 630
a diffusion of portions of the first resin and the second resin
over the channel length to form a composite resin having a profile
with a plurality of index of refractions in at least one dimension.
In some configurations, the manufacturing system 100 achieves the
plurality of index of refractions in the profile by at least one
of: a flow rate of the first resin and the second resin, a time
allowed for the occurrence of diffusion, a proportion of the first
resin with respect to the second resin, a gradient of temperature
across the diffusion channel, and some combination thereof.
Additional Configurations
[0041] The foregoing description of the embodiments of the
invention has been presented for the purpose of illustration; it is
not intended to be exhaustive or to limit the invention to the
precise forms disclosed. Persons skilled in the relevant art can
appreciate that many modifications and variations are possible in
light of the above disclosure.
[0042] Some portions of this description describe the embodiments
of the invention in terms of algorithms and symbolic
representations of operations on information. These algorithmic
descriptions and representations are commonly used by those skilled
in the data processing arts to convey the substance of their work
effectively to others skilled in the art. These operations, while
described functionally, computationally, or logically, are
understood to be implemented by computer programs or equivalent
electrical circuits, microcode, or the like. Furthermore, it has
also proven convenient at times, to refer to these arrangements of
operations as modules, without loss of generality. The described
operations and their associated modules may be embodied in
software, firmware, hardware, or any combinations thereof.
[0043] Any of the steps, operations, or processes described herein
may be performed or implemented with one or more hardware or
software modules, alone or in combination with other devices. In
one embodiment, a software module is implemented with a computer
program product comprising a computer-readable medium containing
computer program code, which can be executed by a computer
processor for performing any or all of the steps, operations, or
processes described.
[0044] Embodiments of the invention may also relate to an apparatus
for performing the operations herein. This apparatus may be
specially constructed for the required purposes, and/or it may
comprise a general-purpose computing device selectively activated
or reconfigured by a computer program stored in the computer. Such
a computer program may be stored in a non-transitory, tangible
computer readable storage medium, or any type of media suitable for
storing electronic instructions, which may be coupled to a computer
system bus. Furthermore, any computing systems referred to in the
specification may include a single processor or may be
architectures employing multiple processor designs for increased
computing capability.
[0045] Embodiments of the invention may also relate to a product
that is produced by a computing process described herein. Such a
product may comprise information resulting from a computing
process, where the information is stored on a non-transitory,
tangible computer readable storage medium and may include any
embodiment of a computer program product or other data combination
described herein.
[0046] Finally, the language used in the specification has been
principally selected for readability and instructional purposes,
and it may not have been selected to delineate or circumscribe the
inventive subject matter. It is therefore intended that the scope
of the invention be limited not by this detailed description, but
rather by any claims that issue on an application based hereon.
Accordingly, the disclosure of the embodiments of the invention is
intended to be illustrative, but not limiting, of the scope of the
invention, which is set forth in the following claims.
* * * * *