U.S. patent application number 14/742886 was filed with the patent office on 2016-12-22 for securing a fresnel lens to a refractive optical element.
The applicant listed for this patent is Oculus VR, LLC. Invention is credited to Matt Lee Thomas.
Application Number | 20160370510 14/742886 |
Document ID | / |
Family ID | 57483912 |
Filed Date | 2016-12-22 |
United States Patent
Application |
20160370510 |
Kind Code |
A1 |
Thomas; Matt Lee |
December 22, 2016 |
SECURING A FRESNEL LENS TO A REFRACTIVE OPTICAL ELEMENT
Abstract
A headset for virtual reality applications includes an optical
element configured to modify light from an electronic display in
the headset and to direct the modified light to a user. The optical
element may include a Fresnel lens secured to a lens by securing
the Fresnel lens to a mold and inserting a casting material into
the mold so the casting material forms the lens and a portion of
the casting material exists on and past an edge of the Fresnel
lens. This encases the edge of the Fresnel lens in the casting
material, securing the Fresnel lens to the lens.
Inventors: |
Thomas; Matt Lee; (Buena
Park, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Oculus VR, LLC |
Menlo Park |
CA |
US |
|
|
Family ID: |
57483912 |
Appl. No.: |
14/742886 |
Filed: |
June 18, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 39/10 20130101;
B29D 11/00403 20130101; G02B 27/0172 20130101; B32B 2551/00
20130101; G02B 3/08 20130101; B29L 2031/3475 20130101; B29D
11/00269 20130101; B29D 11/0073 20130101; G06F 1/163 20130101; B29L
2011/005 20130101; G02B 7/02 20130101; G02B 27/017 20130101; G02B
27/0037 20130101 |
International
Class: |
G02B 3/08 20060101
G02B003/08 |
Claims
1. A method comprising: securing a diffractive element to a portion
of a surface of a portion of a molding structure; assembling the
portion of the molding structure and an additional portion of the
molding structure to form an assembled mold, the assembled mold
having a first specified distance between a surface of the
diffractive element and an inner surface of the additional portion
of the molding structure and having a second specified distance
between the surface of the diffractive element and an inner surface
of the portion of the molding structure along an exterior portion
of the diffractive element; and inserting a casting material into
the assembled mold to form a layer filling the first specified
distance between the surface of the diffractive element and the
inner surface of the additional portion of the molding structure
and another layer filling the second specified distance between the
exterior portion of the surface of the diffractive element and the
inner surface of the portion of the molding structure.
2. The method of claim 1, wherein the casting material is
resin.
3. The method of claim 1, wherein the exterior portion of the
surface of the diffractive element includes one or more openings
for creating molded pins when the casting material is inserted into
the assembled mold.
4. The method of claim 1, wherein the second specified distance
between the surface of the diffractive element and the inner
surface of the portion of the molding structure along the exterior
portion of the diffractive element is equal to a thickness of the
diffractive element.
5. The method of claim 1, wherein the second specified distance
between the surface of the diffractive element and the inner
surface of the portion of the molding structure along the exterior
portion of the diffractive element is equal to a thickness of the
diffractive element and a value.
6. The method of claim 1, wherein the assembled mold has a distance
between an additional surface of the diffractive element that is
parallel to the surface of the diffractive element and the inner
surface of the portion of the molding structure, the distance
extending an overlap distance from an edge of the diffractive
element into the additional surface of the diffractive element.
7. The method of claim 6, wherein inserting a casting material into
the assembled mold further forms a layer between the additional
surface of the diffractive element and the inner surface of the
portion of the molding structure along the overlap distance.
8. The method of claim 1, wherein the exterior portion of the
diffractive element is located outside of a field of view of a user
viewing content through the diffractive element.
9. The method of claim 1, wherein the layer between the surface of
the diffractive element and the inner surface of the additional
portion of the molding structure comprises a lens.
10. The method of claim 1, wherein the diffractive element is
secured to the portion of the surface of the molding structure by
inserting one or more pins through the exterior portion of the
diffractive element.
11. The method of claim 1, wherein the diffractive element
comprises a Fresnel lens.
12. A virtual reality headset having at least one component
manufactured by a method comprising: securing a diffractive element
to a portion of a surface of a portion of a molding structure;
assembling the portion of the molding structure and an additional
portion of the molding structure to form an assembled mold, the
assembled mold having a first specified distance between a surface
of the diffractive element and an inner surface of the additional
portion of the molding structure and having a second specified
distance between the surface of the diffractive element and an
inner surface of the portion of the molding structure along an
exterior portion of the diffractive element; and inserting a
casting material into the assembled mold to form a layer filling
the first specified distance between the surface of the diffractive
element and the inner surface of the additional portion of the
molding structure and another layer filling the second specified
distance between the exterior portion of the surface of the
diffractive element and the inner surface of the portion of the
molding structure.
13. The virtual reality headset of claim 12, wherein the casting
material is resin.
14. The virtual reality headset of claim 12, wherein the exterior
portion of the surface of the diffractive element includes one or
more openings for creating molded pins when the casting material is
inserted into the assembled mold.
15. The virtual reality headset of claim 12, wherein the second
specified distance between the surface of the diffractive element
and the inner surface of the portion of the molding structure along
the exterior portion of the diffractive element is equal to a
thickness of the diffractive element.
16. The virtual reality headset of claim 12, wherein the second
specified distance between the surface of the diffractive element
and the inner surface of the portion of the molding structure along
the exterior portion of the diffractive element is equal to a
thickness of the diffractive element and a value.
17. The virtual reality headset of claim 12, wherein the assembled
mold has a distance between an additional surface of the
diffractive element that is parallel to the surface of the
diffractive element and the inner surface of the portion of the
molding structure, the distance extending an overlap distance from
an edge of the diffractive element into the additional surface of
the diffractive element.
18. The virtual reality headset of claim 17, wherein inserting the
casting material into the assembled mold further forms a layer
between the additional surface of the diffractive element and the
inner surface of the portion of the molding structure along the
overlap distance.
19. The virtual reality headset of claim 12, wherein the exterior
portion of the diffractive element is located outside of a field of
view of a user viewing content through the diffractive element.
20. The virtual reality headset of claim 12, wherein the layer
between the surface of the diffractive element and the inner
surface of the additional portion of the molding structure
comprises a lens.
21. The virtual reality headset of claim 12, wherein the
diffractive element is secured to the portion of the surface of the
molding structure by inserting one or more pins through the
exterior portion of the diffractive element.
Description
BACKGROUND
[0001] This disclosure relates generally to manufacturing
processes, and more specifically to securing a Fresnel lens to a
refractive optical element.
[0002] Electronic displays include a plurality of pixels, which may
each include a plurality of sub-pixels (e.g., a red sub-pixel, a
green sub-pixel, etc.). Arrangement of individual sub-pixels may
affect the appearance and performance of an electronic display
device. Some arrangements of sub-pixels may increase fixed pattern
noise under certain conditions. For example, magnification of a
pixel may result in boundaries between individual sub-pixels of the
pixel becoming visible to the user, resulting in a "screen door"
pattern (i.e., an increase in fixed pattern noise) in an image
presented to a user. While corrective optical elements may be used
to reduce the effect of fixed pattern noise in content presented by
the user, conventional corrective optical elements are difficult to
rapidly manufacture. For example, certain types of corrective
optical elements are lenses in which multiple grooves are etched,
which precludes the lenses from being molded. The additional time
and expense of etching grooves into the lenses after the lenses are
molded increases the time and expense in producing these corrective
optical elements.
SUMMARY
[0003] An optical element for viewing content presented via an
electronic display includes a diffractive element, such as a
Fresnel lens, that modifies light presented by the electronic
display and directs the modified light to a user for presentation.
For example, the Fresnel lens blurs light generated by different
sub-pixels in an image presented by the electronic display to
prevent the user from seeing dark space between the sub-pixels and
a refractive optical element (e.g., a lens) directs the blurred
light to a user's eye. The Fresnel lens includes a series of
equally spaced grooves, with the distance between the grooves
referred to as "pitch width." The pitch width determines the amount
by which light from sub-pixels presented by the electronic display
is blurred by the Fresnel lens. However, the grooves included in a
Fresnel lens prevent the Fresnel lens from being fabricated via
molding. Instead, a lens is initially generated via a molding
process, and the grooves are subsequently etched into the lens to
product the Fresnel lens, which increases the time and complexity
of generating the Fresnel lens.
[0004] To simplify production of the optical element for viewing
content presented via the electronic display, a Fresnel lens or
other suitable diffractive element is secured to a surface of a
molding structure. For example, the Fresnel lens is secured to a
surface of a molding structure through one or more pins inserted
through an exterior portion of the Fresnel lens (e.g., a portion
within a threshold distance of an edge of the Fresnel lens and
outside of a field of view of a user) and into the surface of the
molding structure. The exterior portion of the Fresnel lens may be
an edge of the surface of Fresnel lens or a portion of the surface
of Fresnel lens between a specified distance from the edge of the
surface of Fresnel lens and the edge of the surface of the Fresnel
lens (e.g., from the edge of the Fresnel lens to 0.1 millimeters
from the edge of the Fresnel lens). In various embodiments, the
exterior portion of the surface of the Fresnel lens is specified so
that it is outside of a field of view of a user who views data
through the Fresnel lens or through an optical element coupled to
the Fresnel lens. After securing the Fresnel lens to the surface of
the molding structure, the mold is assembled using one or more
additional portions. For example, an additional portion of the
molding structure is positioned relative to the portion of the
molding structure to which the Fresnel lens is secured. In various
embodiments, the additional portion of the molding structure is
positioned so there is a specified distance between a surface of
the Fresnel lens and an inner surface of the additional portion of
the molding structure. Distances between different locations on the
inner surface of the additional portion of the molding structure
and a location on the surface of the Fresnel lens may differ in
some embodiments, so different locations on the inner surface of
the additional portion of the molding structure have different
distances to the location on the surface of the Fresnel lens.
[0005] In some embodiments, when the mold is assembled, the
assembled mold also has a specified distance between the surface of
the Fresnel lens and an inner surface of the portion of the molding
structure to which the Fresnel lens is secured. For example, the
specified distance between the surfaces of the Fresnel lens ant eh
inner surface of the portion of the molding structure is along an
exterior portion of the surface of Fresnel lens from the surface of
the Fresnel lens to the inner surface of the portion of the molding
structure. The assembled mold may also have a distance between an
exterior portion of an additional surface of the Fresnel lens that
is parallel to the surface of the Fresnel lens (e.g., a surface of
the Fresnel lens nearer to the molding structure) and the inner
surface of the portion of the molding structure to which the
Fresnel lens is secured, creating separation between the additional
surface of the Fresnel lens and the inner surface of the molding
structure between the edge of the Fresnel lens and a location on
the additional surface of the Fresnel lens that is a specified
distance from the edge of the Fresnel lens. Additionally, the
exterior portion of the surface of Fresnel lens may include one or
more openings extending from the surface of the Fresnel lens
through the thickness of the Fresnel lens or through a portion of
the thickness of the Fresnel lens.
[0006] A casting material, such as resin, that is transmissible to
one or more wavelengths of light is inserted into the assembled
mold, forming a layer between the additional portion of the molding
structure and the surface of the Fresnel lens that has a thickness
equaling the specified distance between the surface of the Fresnel
lens and the inner surface of the additional portion of the molding
structure. In some embodiments, the layer formed between the
surface of the Fresnel lens and the inner surface of the additional
portion of the molding structure creates a lens or other refractive
element that affects the focusing of light passing through the
layer. Distances between a location on the surface of the Fresnel
lens and locations on the inner surface of the additional portion
of the molding structure determine the curvature of the lens in
various embodiments. If the assembled mold has a specified distance
between the surface of the Fresnel lens and an inner surface of the
portion of the molding structure to which the Fresnel lens is
secured, inserting the casting material into the assembled mold
forms a layer of the casting material between the surface of the
Fresnel lens and the portion of the molding structure. For example,
if the specified distance is along an exterior portion of the
Fresnel lens from the surface of the Fresnel lens to the inner
surface of the portion of the molding structure, a layer of the
casting material is formed along the exterior portion of the
Fresnel lens from the surface of the Fresnel lens to the inner
surface of the portion of the molding structure. This encases the
exterior portion of the Fresnel lens in the casting material from
the surface of the Fresnel lens to the inner surface of the portion
of the molding structure. In embodiments where the assembled mold
has a distance between an exterior portion of an additional surface
of the Fresnel lens that is parallel to the surface of the Fresnel
lens (e.g., a surface of the Fresnel lens nearer to the molding
structure) and the inner surface of the portion of the molding
structure to which the Fresnel lens is secured, inserting the
casting material into the assembled mold also generates a layer of
casting material between the additional surface of the Fresnel lens
and the inner surface of the molding structure. This layer of
casting material secures the Fresnel lens to the layer of casting
material between the surface of the Fresnel lens and the inner
surface of the additional molding structure. Hence, the casting
material forms a layer between the additional surface of the
Fresnel lens and the inner surface of the molding structure
extending an overlap distance from the edge of the Fresnel lens to
a location on the additional surface of the Fresnel lens. In
embodiments where the Fresnel lens includes one or more openings in
the exterior portion of the surface of the Fresnel lens, inserting
the casting material into the assembled mold causes the casting
material to flow through the openings, forming molded pins. The
assembled mold is subsequently removed after the casting material
cures or hardens to produce an optical element where the Fresnel
lens is secured to a refractive optical element, such as a lens,
that directs light from the Fresnel lens to a user.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1A is a wire diagram of a virtual reality (VR) headset,
in accordance with an embodiment.
[0008] FIG. 1B is a cross section of a front rigid body of the VR
headset in FIG. 1A, in accordance with an embodiment.
[0009] FIG. 2 is an optical block of a VR headset including a
Fresnel lens and a refractive optical element, in accordance with
an embodiment.
[0010] FIG. 3 is a flowchart of a method for securing a Fresnel
lens to a refractive optical element, according to one
embodiment.
[0011] FIG. 4A is an example of securing a Fresnel lens to a mold,
according to one embodiment.
[0012] FIG. 4B is an additional example of securing a Fresnel lens
to a mold, according to one embodiment
[0013] FIG. 4C is an example of inserting a casting material into a
mold to which a Fresnel lens has been secured, according to one
embodiment.
[0014] FIG. 4D is an example of a Fresnel lens secured to a
refractive optical material generated by casting material,
according to one embodiment.
[0015] The figures depict various embodiments 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 described herein.
DETAILED DESCRIPTION
Example Outer Shell
[0016] FIG. 1A is a wire diagram of a virtual reality (VR) headset,
in accordance with an embodiment. The VR headset 100 includes a
front rigid body 105 and a band 110. The front rigid body 105
includes one or more electronic display elements of an electronic
display, and may include an inertial measurement unit (IMU) 130,
one or more position sensors 117, and locators 125. In the
embodiment shown by FIG. 1A, the position sensors 117 are located
within the IMU 130, and neither the IMU 130 nor the position
sensors 117 are visible to the user.
[0017] The locators 125 are located in fixed positions on the front
rigid body 105 relative to one another and relative to a reference
point 115. In the example of FIG. 1A, the reference point 115 is
located at the center of the IMU 130. Each of the locators 125 emit
light that is detectable by an imaging device. Locators 125, or
portions of locators 125, are located on a front side 120A, a top
side 120B, a bottom side 120C, a right side 120D, and a left side
120E of the front rigid body 105 in the example of FIG. 1A.
[0018] The IMU 130 is an electronic device that generates fast
calibration data based on measurement signals received from one or
more of the position sensors 117. A position sensor 117 generates
one or more measurement signals in response to motion of the VR
headset 100. Examples of position sensors 117 include: one or more
accelerometers, one or more gyroscopes, one or more magnetometers,
another suitable type of sensor that detects motion, a type of
sensor used for error correction of the IMU 130, or some
combination thereof. The position sensors 117 may be located
external to the IMU 130, internal to the IMU 130, or some
combination thereof
[0019] Based on the one or more measurement signals from one or
more position sensors 117, the IMU 130 generates fast calibration
data indicating an estimated position of the VR headset 100
relative to an initial position of the VR headset 100. For example,
the position sensors 117 include multiple accelerometers to measure
translational motion (forward/back, up/down, left/right) and
multiple gyroscopes to measure rotational motion (e.g., pitch, yaw,
roll). In some embodiments, the IMU 130 rapidly samples the
measurement signals and calculates the estimated position of the VR
headset 100 from the sampled data. For example, the IMU 130
integrates the measurement signals received from the accelerometers
over time to estimate a velocity vector and integrates the velocity
vector over time to determine an estimated position of a reference
point on the VR headset 100. Alternatively, the IMU 130 provides
the sampled measurement signals to the VR console 110, which
determines the fast calibration data. The reference point is a
point that may be used to describe the position of the VR headset
100, such as the reference point 115. While the reference point 115
may generally be defined as a point in space, the reference point
115 is defined as a point within the VR headset 100 (e.g., a center
of the IMU 130) in various embodiments.
[0020] The IMU 130 receives one or more calibration parameters from
a virtual reality (VR) console and uses the one or more calibration
parameters to maintain tracking of the VR headset 100. Based on a
received calibration parameter, the IMU 130 may adjust one or more
IMU parameters (e.g., sample rate). In some embodiments, certain
calibration parameters cause the IMU 130 to update an initial
position of the reference point so it corresponds to a next
calibrated position of the reference point. Updating the initial
position of the reference point as the next calibrated position of
the reference point helps reduce accumulated error associated with
the determined estimated position. The accumulated error, also
referred to as drift error, causes the estimated position of the
reference point to "drift" away from the actual position of the
reference point over time.
[0021] FIG. 1B is a cross section 125 of the front rigid body 105
of the embodiment of a VR headset 100 shown in FIG. 1A. As shown in
FIG. 1B, the front rigid body 105 includes an optical block 140,
which provides altered image light to an exit pupil 150. The exit
pupil 150 is the location of the front rigid body 105 where a
user's eye 135 is positioned. For purposes of illustration, FIG. 1B
shows a cross section 125 associated with a single eye 135, but
another optical block, separate from the optical block 140,
provides altered image light to another eye of the user.
[0022] The optical block 140 includes an electronic display element
135 of the electronic display 115 that projects image light toward
the corrective optics block 118, which is included in the optical
block 130 and alters the projected image. For example, the
corrective optics block 118 magnifies and corrects optical errors
associated with the projected image. The optical block 230 is
configured to correct for fixed pattern noise by slightly blurring
sub-pixels. The corrective optics block 118 directs the altered
image light to the exit pupil 150 for presentation to the user.
[0023] The electronic display 115 includes a display area
comprising a plurality of sub-pixels, where a sub-pixel is a
discrete light emitting component. Different sub-pixels are
separated from each other by dark space. For example, a sub-pixel
emits red light, yellow light, blue light, green light, white
light, or any other suitable color of light. In some embodiments,
images projected by the electronic display 115 are rendered on the
sub-pixel level. This is distinct from, say an RGB (red-green-blue)
layout, which has discrete red, green, and blue pixels (red, green,
and blue) and each pixel in the RGB layout includes a red
sub-pixel, which is adjacent to a green sub-pixel that is adjacent
to a blue sub-pixel; the red, green, and blue sub-pixels operate
together to form different colors. In an RGB layout a sub-pixel in
a pixel is restricted to working within that pixel. However, in
some embodiments, sub-pixels in the electronic display operate
within multiple "logical" pixels in their surrounding vicinity to
form different colors. The sub-pixels are arranged on the display
area of the electronic display 115 in a sub-pixel array. Examples
of a sub-pixel array include PENTILE.RTM. RGBG, PENTILE.RTM. RGBW,
some another suitable arrangement of sub-pixels that renders images
at the sub-pixel level.
[0024] The corrective optics block 118 includes one or more optical
elements that adjust an image projected by the electronic display
115 to the user by the VR headset 100. In some embodiments, the
corrective optics block 118 is positioned at least 35 mm from the
electronic display 115. At least a portion of an optical element in
the corrective optics block 118 includes a diffractive surface. In
various embodiments, an optical element in the corrective optics
block includes a refractive surface (e.g., a concave surface), a
diffractive surface (e.g., a Fresnel surface, a binary surface,
some other type of diffractive element), or some combination
thereof. Portions of the diffractive surface and/or the refractive
surface may include a flat portion, a curved portion, or both. The
diffractive surface of an optical element may be uniform or may
have a higher density of grooves near the center of the optical
element. A diffractive optical element is an optical element
including at least a portion of a diffractive surface.
Additionally, in some embodiments, an optical element may be an
aperture, a filter, or any other suitable optical element that
affects the image projected by the electronic display 115. In some
embodiments, one or more of the optical elements in the corrective
optics block 118 may have one or more coatings, such as
anti-reflective coatings.
[0025] The corrective optics block 118 magnifies image light
projected by the electronic display 115 and corrects optical errors
associated with the image light. Magnification of the image light
allows the electronic display 115 to be physically smaller, weigh
less, and consume less power than larger displays. Additionally,
magnification may increase a field of view of the displayed media.
For example, the field of view of the displayed media is such that
the displayed media is presented using almost all (e.g., 110
degrees diagonal), and in some cases all, of the user's field of
view. However, magnification may cause an increase in fixed pattern
noise, also referred to as the "screen door effect," which is a
visual artifact where dark space separating pixels and/or
sub-pixels of a display become visible to a user in an image
presented by the display. For example, magnification without
optical error correction may increase fixed pattern noise to the
point where the projected image suffers from the screen door
effect. In some embodiments, the corrective optics block 118 is
designed so its effective focal length is larger than the spacing
to the electronic display 115, which magnifies the image light
projected by the electronic display 115. Additionally, in some
embodiments, the amount of magnification may be adjusted by adding
or removing optical elements.
[0026] The corrective optics block 118 may be designed to correct
one or more types of optical error. Optical error may be fixed
pattern noise (i.e., the screen door effect), two dimensional
optical errors, three dimensional optical errors, or some
combination thereof. Two dimensional errors are optical aberrations
that occur in two dimensions. Example types of two dimensional
errors include: barrel distortion, pincushion distortion,
longitudinal chromatic aberration, transverse chromatic aberration,
or any other type of two-dimensional optical error. Three
dimensional errors are optical errors that occur in three
dimensions. Example types of three dimensional errors include
spherical aberration, comatic aberration, field curvature,
astigmatism, or any other type of three-dimensional optical error.
The corrective optics block 118 may correct for fixed pattern noise
by slightly blurring the image of each sub-pixel so the blurred
sub-pixels mask the dark space between the sub-pixels via a Fresnel
lens or other diffractive surface. In some embodiments, the media
provided to the electronic display 115 for display is
pre-distorted, and the corrective optics block 118 corrects the
distortion.
[0027] FIG. 2 is an example optical block 200 where the corrective
optics block 118 includes an optical element 210 having a Fresnel
surface, such as a Fresnel lens 220, and a separate refractive
optical element 230 (e.g., a lens). The optical element 210 and the
separate refractive optical element 230 are shaped and positioned
to magnify the electronic display 145 and correct for fixed pattern
noise, as well as correct for one or more additional optical
errors. Because the optical block 200 shown in FIG. 2 has discrete
refractive and diffractive elements, the optical block 200 is
simpler to manufacture than an optical block combining the
diffractive and refractive properties into a single optical
element, which may result in difficulties in manufacturing and
potential problems with glare. The Fresnel surface 220 of the
optical element 210 is positioned to receive image light from the
electronic display element 145 and generate blur spots, by
diffracting image light from the electronic display element
145.
[0028] The refractive optical element 230 is a convex lens that
provides the diffracted image light to an exit pupil 240. As shown
in FIG. 2, the refractive optical element 230 includes a first
surface 232 that receives diffracted light from the optical element
210 and a second surface 234 that directs the diffracted light
toward an exit pupil 240. The first surface 232 and the second
surface 234 have different curvatures, with the curvatures of the
surfaces 232, 234 selected to direct the diffracted light to the
exit pupil 240, to minimize introduction of optical error, to
correct one or more optical errors, or to perform any suitable
function.
Process for Securing a Fresnel Lens to a Lens
[0029] FIG. 3 is one embodiment of a method for securing a Fresnel
lens, or other diffractive surface, to a lens or other refractive
optical element. In various embodiments, the method may include
different and/or additional steps than those described in
conjunction with FIG. 3. Additionally, in some embodiments, steps
of the method may be performed in different orders.
[0030] Initially, a diffractive element, such as a Fresnel lens, is
secured 310 to a surface of a molding structure. For example, the
Fresnel lens is secured to a surface of a molding structure through
one or more pins inserted through an exterior portion of the
Fresnel lens (e.g., a portion within a threshold distance of an
edge of the Fresnel lens) and into the surface of the molding
structure. Alternatively, the Fresnel lens is secured 310 to a
surface of the molding structure through suction (e.g., through
creating a vacuum). For example, the surface of the molding
structure includes one or more openings, allowing a pressure
difference between the surface of the molding structure and another
surface of the molding structure parallel to the surface to secure
310 the Fresnel lens to the surface of the molding structure (e.g.,
through creating a vacuum).
[0031] After securing 310 the Fresnel lens to the surface of the
molding structure, the mold is assembled 320 using one or more
additional portions. For example, an additional portion of the
molding structure is positioned relative to the portion of the
molding structure to which the Fresnel lens is secured 310. In
various embodiments, the additional portion of the molding
structure is positioned so there is a specified distance between a
surface of the Fresnel lens and an inner surface of the additional
portion of the molding structure. For example, the specified
distance is between a center of the surface of the Fresnel lens and
a specific location of the inner surface of the additional portion
of the molding structure. In some embodiments, there are different
distances between different locations on the surface of the Fresnel
lens and different locations on the inner surface of the additional
portion of the molding structure. Alternatively, the additional
portion of the molding structure is positioned so a distance
between the center of the surface of the Fresnel lens and various
locations on the inner surface of the additional portion of the
molding structure is constant (e.g., positioned so a semicircle
with a specific radius from the center of the surface from the
Fresnel lens is formed between the surface of the Fresnel lens and
the inner surface of the additional portion of the molding
structure).
[0032] In some embodiments, when the mold is assembled, the
assembled mold has a specified distance between the surface of the
Fresnel lens and an inner surface of the portion of the molding
structure to which the Fresnel lens is secured 310. For example,
the specified distance is along an exterior portion of the surface
of Fresnel lens from the surface of the Fresnel lens to the inner
surface of the portion of the molding structure. In some
embodiments, the specified distance between the surface of the
Fresnel lens and the inner surface of the portion of the molding
structure to which the Fresnel lens is secured 310 is equal to the
thickness of the Fresnel lens. Alternatively, the specified
distance between the surface of the Fresnel lens and the inner
surface of the portion of the molding structure to which the
Fresnel lens is secured 310 is equal to the thickness of the
Fresnel lens incremented by a value, so the specified distance is
greater than the thickness of the Fresnel lens. The exterior
portion of the Fresnel lens may be an edge of the surface of
Fresnel lens or a portion of the surface of Fresnel lens between a
specified distance from the edge of the surface of Fresnel lens and
the edge of the surface of the Fresnel lens (e.g., from the edge of
the Fresnel lens to 0.1 millimeters from the edge of the Fresnel
lens). In various embodiments, the exterior portion of the surface
of the Fresnel lens is specified so that it is outside of a field
of view of a user who views data through the Fresnel lens or
through an optical element coupled to the Fresnel lens.
[0033] The assembled mold may have a distance between the inner
surface of the portion of the molding structure to which the
Fresnel lens is secured and an exterior portion of an additional
surface of the Fresnel lens that is parallel to the surface of the
Fresnel lens (e.g., a surface of the Fresnel lens nearer to the
portion of the molding structure). Hence, there is separation
between the additional surface of the Fresnel lens and the inner
surface of the molding structure between the edge of the Fresnel
lens and a location on the additional surface of the Fresnel lens
that is a specified distance from the edge of the Fresnel lens,
also referred to as an "overlap distance." Additionally, the
exterior portion of the surface of Fresnel lens may include one or
more openings extending from the surface of the Fresnel lens
through the thickness of the Fresnel lens or through a portion of
the thickness of the Fresnel lens.
[0034] A casting material, such as resin, that is transmissible to
one or more wavelengths of light is inserted 330 into the assembled
mold. The casting material forms a layer between the additional
portion of the molding structure and the surface of the Fresnel
lens that has a thickness equaling the specified distance between
the surface of the Fresnel lens and the inner surface of the
additional portion of the molding structure. In some embodiments,
the layer formed between the surface of the Fresnel lens and the
inner surface of the additional portion of the molding structure
creates a lens that affects the focusing of light passing through
the layer. Distances between a location on the surface of the
Fresnel lens and locations on the inner surface of the additional
portion of the molding structure determine the curvature of the
lens in various embodiments. Additionally, if the assembled mold
has a specified distance between the surface of the Fresnel lens
and an inner surface of the portion of the molding structure to
which the Fresnel lens is secured 310, inserting 330 the casting
material into the assembled mold forms a layer of the casting
material between the surface of the Fresnel lens and the portion of
the molding structure. For example, if the specified distance
between the surface of the Fresnel lens and an inner surface of the
portion of the molding structure to which the Fresnel lens is
secured 310 is along an exterior portion of the Fresnel lens from
the surface of the Fresnel lens to the inner surface of the portion
of the molding structure, a layer of the casting material is formed
along the exterior portion of the Fresnel lens from the surface of
the Fresnel lens to the inner surface of the portion of the molding
structure. This configuration encases the exterior portion of the
Fresnel lens in the casting material from the surface of the
Fresnel lens to the inner surface of the portion of the molding
structure. In some embodiments, the assembled mold has a distance
between an exterior portion of an additional surface of the Fresnel
lens that is parallel to the surface of the Fresnel lens (e.g., a
surface of the Fresnel lens nearer to the molding structure) and
the inner surface of the portion of the molding structure to which
the Fresnel lens is secured, so inserting 330 the casting material
into the assembled mold also generates a layer of casting material
between the additional surface of the Fresnel lens and the inner
surface of the molding structure. Hence, the casting material forms
a layer between the additional surface of the Fresnel lens and the
inner surface of the molding structure extending an overlap
distance from the edge of the Fresnel lens to a location on the
additional surface of the Fresnel lens. If the Fresnel lens
includes one or more openings in the exterior portion of the
surface of the Fresnel lens, inserting 330 the casting material
into the assembled mold causes the casting material to flow through
the openings, which forms molded pins when the casting material
cures. The assembled mold is subsequently removed 340 after the
casting material cures or hardens to produce an optical element
where the Fresnel lens is secured to a lens.
[0035] FIG. 4A is an example of an assembled mold 400 with a
Fresnel lens 220 secured to a surface of a portion of a molding
structure 410A. The assembled mold 400 includes an additional
molding structure 420 having a surface that is separated from a
surface of the Fresnel lens 220 by a first specified distance 430.
In the example of FIG. 4A, various locations along the surface of
the additional molding structure 420 have a common distance from a
location in the center of the surface of the Fresnel lens 220.
Additionally, in the example of FIG. 4A, the assembled mold 400 has
a second specified distance 440 between the surface of the Fresnel
lens 220 and an inner surface of the portion of the molding
structure 410A. For example, the second specified distance 440 is
along an exterior portion of the surface of Fresnel lens 220 from
the surface of the Fresnel lens 220 to the inner surface of the
portion of the molding structure 410A. As described above in
conjunction with FIG. 3, the exterior portion of the Fresnel lens
220 may be an edge of the surface of Fresnel lens 220 or a portion
of the surface of Fresnel lens 220 between a specified distance
from the edge of the surface of Fresnel lens 220 and the edge of
the surface of the Fresnel lens 220 that is outside of a field of
view of a user who views data through the Fresnel lens or through
an optical element coupled to the Fresnel lens 220.
[0036] FIG. 4B is an additional example of the assembled mold 400
with a Fresnel lens 220 secured to a surface secured to a surface
of a portion of a molding structure 410B. As in the example of FIG.
4A, the assembled mold 400 includes an additional molding structure
420 having a surface that is separated from a surface of the
Fresnel lens 220 by a first specified distance 430 and has a second
specified distance 440 between the surface of the Fresnel lens 220
and an inner surface of the portion of the molding structure 410B.
Additionally, the assembled mold 400 in FIG. 4B have a distance
between the inner surface of the portion of the molding structure
400B and an exterior portion of an additional surface of the
Fresnel lens 220 extending from the edge of the Fresnel lens 220 an
overlap distance 450 into the additional surface of the Fresnel
lens 220. This creates separation between the additional surface of
the Fresnel lens 220 and the inner surface of the portion of the
molding structure 410B along the overlap distance 450 between the
edge of the Fresnel lens and a location on the additional surface
of the Fresnel lens 220 that is a specified distance from the edge
of the Fresnel lens 220.
[0037] FIG. 4C is an example of inserting a casting material into
an assembled mold 400 to which a Fresnel lens has been secured,
according to one embodiment. In FIG. 4C, a casting material, such
as resin, is inserted into the assembled mold 400 shown in FIG. 4A.
The casting material fills the first specified distance 430 between
the surface of the Fresnel lens 220 and the surface of the
additional portion of the molding structure 420 as well as the
second specified distance 440 between the surface of the Fresnel
lens 220 and the inner surface of the portion of the molding
structure 410A. In other embodiments, inserting the casting
material into the assembled mold 400 fills distances between the
inner surface of the portion of the molding structure to which the
Fresnel lens 220 is secured and an additional surface of the
Fresnel lens 220, such as distances between the additional surface
of the Fresnel lens 220 and the inner surface of a molding
structure 410B along the overlap distance 450 shown in FIG. 4B.
After the casting material has set, cured, or hardened, FIG. 4D
shows an optical element 450 including the Fresnel lens 220 secured
to a refractive optical element 230 formed by the cured casting
material.
[0038] Securing the Fresnel lens to a portion of a surface of a
molding structure and subsequently inserting casting material into
an assembled mold inclosing the molding structure and the Fresnel
lens allows the Fresnel lens to be secured to a refractive optical
element, such as a lens, produced when the casting material cures.
Separation between regions of the Fresnel lens and the surface of
the molding structure allows the casting material to encase
portions of the Fresnel lens (e.g., an edge of the Fresnel lens, an
amount of the Fresnel lens between the edge and a specified
distance from the edge), which secures the Fresnel lens to the
refractive optical element generated when casting material between
a surface of the Fresnel lens and a surface of a portion of an
additional molding structure cures. While the preceding examples
describe securing a Fresnel lens to a refractive optical element,
in other embodiments, any suitable diffractive optical element may
be secured to the portion of the surface of the molding structure
and casting material inserted into an assembled mold including the
diffractive optical element and the molding structure, as described
above in conjunction with FIGS. 2-4D.
Summary
[0039] 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.
[0040] 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.
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