NZ735537B2 - Improved manufacturing for virtual and augmented reality systems and components - Google Patents
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Abstract
method for manufacturing an eyepiece comprising a first diffractive optical element is disclosed. The claimed method produces an eyepiece for presenting 3D content to the user of an augmented reality system which has different focal planes and enhances the perception of multiple depths. The method comprises: depositing a first layer onto a first substrate, wherein the first layer comprises a first portion and a second portion, the first portion is deposited to have a first depth onto a first region on the first substrate, the first portion has a first optical index, the second portion is deposited to have a second depth onto a second region on the first substrate, and the second portion has a second optical index different from the first optical index; identifying a template having an imprint pattern formed thereon, the template comprising a first set of depth structures and a second set of depth structures, the first set of depth structures corresponding to the first depth of the first portion, and the second set of depth structures corresponding to the second depth of the second portion; and imprinting the imprint pattern into the first and the second portions on the first substrate with the template, wherein the imprint pattern comprises a diffraction pattern for the first diffractive optical element, the first portion is deposited to have the first depth according to at least a first optical function, the second portion is deposited to have the second depth according to at least a second optical function, before imprinting, and the first depth is different from the second depth. d comprises: depositing a first layer onto a first substrate, wherein the first layer comprises a first portion and a second portion, the first portion is deposited to have a first depth onto a first region on the first substrate, the first portion has a first optical index, the second portion is deposited to have a second depth onto a second region on the first substrate, and the second portion has a second optical index different from the first optical index; identifying a template having an imprint pattern formed thereon, the template comprising a first set of depth structures and a second set of depth structures, the first set of depth structures corresponding to the first depth of the first portion, and the second set of depth structures corresponding to the second depth of the second portion; and imprinting the imprint pattern into the first and the second portions on the first substrate with the template, wherein the imprint pattern comprises a diffraction pattern for the first diffractive optical element, the first portion is deposited to have the first depth according to at least a first optical function, the second portion is deposited to have the second depth according to at least a second optical function, before imprinting, and the first depth is different from the second depth.
Description
IMPROVED MANUFACTURING FOR VIRTUAL AND AUGMENTED REALITY
SYSTEMS AND COMPONENTS
FIELD OF THE INVENTION
The present disclosure relates to virtual reality and augmented reality imaging and
visualization systems.
BACKGROUND
Modern computing and display technologies have facilitated the development of
systems for so called “virtual reality” or “augmented reality” experiences, wherein digitally
reproduced images or portions thereof are presented to a user in a manner wherein they seem to
be, or may be perceived as, real. A virtual reality, or “VR”, scenario typically involves
presentation of digital or virtual image information without transparency to actual real-world
visual input. An augmented reality, or “AR”, scenario typically involves presentation of digital
or virtual image information as an augmentation to visualization of the actual world around the
user. For example, referring to Fig. 1, an augmented reality scene (4) is depicted wherein a user
of an AR technology sees a real-world park-like setting (6) featuring people, trees, buildings in
the background, and a concrete platform (1120). In addition to these items, the user of the AR
technology also perceives that he “sees” a robot statue (1110) standing upon the real-world
platform (1120), and a cartoon-like avatar character (2) flying by which seems to be a
personification of a bumble bee, even though these elements (2, 1110) do not exist in the real
world. As it turns out, the human visual perception system is very complex, and producing a
VR or AR technology that facilitates a comfortable, natural-feeling, rich presentation of virtual
image elements amongst other virtual or real-world imagery elements is challenging.
There are numerous challenges when it comes to presenting 3D virtual content to a
user of an AR system. A central premise of presenting 3D content to a user involves creating a
perception of multiple depths. In other words, it may be desirable that some virtual content
appear closer to the user, while other virtual content appear to be coming from farther away.
Thus, to achieve 3D perception, the AR system should be configured to deliver virtual content
at different focal planes relative to the user.
In order for a 3D display to produce a true sensation of depth, and more specifically,
a simulated sensation of surface depth, it is desirable for each point in the display's visual field
to generate the accommodative response corresponding to its virtual depth. If the accommodative
response to a display point does not correspond to the virtual depth of that point, as determined
by the binocular depth cues of convergence and stereopsis, the human visual system may
experience an accommodation conflict, resulting in unstable imaging, harmful eye strain,
headaches, and, in the absence of accommodation information, almost a complete lack of surface
depth.
Therefore, there is a need for improved technologies to implement 3D displays that
resolve these and other problems of the conventional approaches. The systems and techniques
described herein are configured to work with the visual configuration of the typical human to
address these challenges.
SUMMARY
Embodiments of the present invention are directed to devices, systems and methods
for facilitating virtual reality and/or augmented reality interaction for one or more users.
An augmented reality (AR) display system for delivering augmented reality content
to a user, according to some embodiments, comprises an image-generating source to provide one
or more frames of image data, a light modulator to transmit light associated with the one or more
frames of image data, a diffractive optical element (DOE) to receive the light associated with the
one or more frames of image data and direct the light to the user’s eyes, the DOE comprising a
diffraction structure having a waveguide substrate corresponding to a waveguide refractive
index, a surface grating, and an intermediate layer (referred to also herein as an “underlayer”)
disposed between the waveguide substrate and the surface grating, wherein the underlayer
corresponds to an underlayer diffractive index that is different from the waveguide refractive
index.
According to some embodiments of the invention, a diffraction structure is employed
for a DOE that includes an underlayer that resides between a waveguide substrate and a top
grating surface. The top grating surface comprises a first material that corresponds to a first
refractive index value, the underlayer comprises a second material that corresponds to a second
refractive index value, and the substrate comprises a third material that corresponds to a third
refractive index value.
Any combination of same or different materials may be employed to implement each
of these portions of structure, e.g., where all three materials are different (and all three correspond
to different refractive index values), or where two of the layers share the same material (e.g.,
where two of the three materials are the same and therefore share a common reflective index
value that differs from the refractive index value of the third material). Any suitable set of
materials may be used to implement any layer of the improved diffraction structure.
Thus a variety of combinations is available wherein an underlayer of one index is
combined with a top grating of another index, along with a substrate of a third index, and wherein
adjusting these relative values provides a lot of variation in dependence of diffraction efficiency
upon incidence angle. A layered waveguide with different layers of refractive indices is
presented. Various combinations and permutations are presented along with related performance
data to illustrate functionality. The benefits include increased angle, which provides an increased
output angle with the grating and therefore an increased field of view with the eyepiece. Further,
the ability to counteract the normal reduction in diffraction efficiency with angle is functionally
beneficial.
According to additional embodiments, improved approaches are provided to
implement deposition of imprint materials onto a substrate, along with imprinting of the imprint
materials to for patterns for implementing diffraction. These approaches allow for very precise
distribution, deposition, and/or formation of different imprint materials/patterns onto any
number of substrate surfaces. According to some embodiments, patterned distribution (e.g.,
patterned inkjet distribution) of imprint materials are performed to implement the deposition of
imprint materials onto a substrate. This approach of using patterned ink-jet distribution allows
for very precise volume control over the materials to be deposited. In addition, this approach
can serve to provide a smaller, more uniform base layer beneath a grating surface.
In some embodiments, a template is provided having a first set of deeper depth
structures along with a second set of shallower depth structures. When depositing imprint
materials onto an imprint receiver, a relatively higher volume of imprint materials is deposited
in conjunction with the deeper depth structures of the template. In addition, a relatively lower
volume of imprint materials is deposited in conjunction with the shallower depth structures of
the template. This approach permits simultaneous deposition of different thicknesses of
materials for the different features to be formed onto the imprint receiver. This approach can
be taken to create distributions that are purposefully non-uniform for structures with different
depths and/or feature parameters, e.g., where the feature structures are on the same substrate and
have different thicknesses. This can be used, for example, to create spatially distributed volumes
of imprint material that enable simultaneous imprint of structures of variable depth with the same
underlayer thickness.
Some embodiments pertain to an approach to implement simultaneous deposition of
multiple types of imprint materials onto a substrate. This permits materials having optical
properties to be simultaneously deposited across multiple portions of the substrate at the same
time. This approach also provides the ability to tune local areas associated with specific
functions, e.g., to act as in-coupling grating, orthogonal pupil expander (OPE) gratings, or exit
pupil expander (EPE) gratings. The different types of materials may comprise the same material
having different optical properties (e.g., two variants of the same material having differing
indices of refraction) or two entirely different materials. Any optical property of the materials
can be considered and selected when employing this technique, e.g., index of refraction, opacity,
and/or absorption.
According to another embodiment, multi-sided imprinting may be employed to
imprint multiple sides of an optical structure. This permits imprinting to occur on different sides
of an optical element, to implement multiplexing of functions through a base layer volume. In
this way, different eyepiece functions can be implemented without adversely affecting grating
structure function. A first template may be used to produce one imprint on side “A” of the
substrate/imprint receiver, forming a first pattern having a first material onto side A of the
structure. Another template may be used to produce a second imprint on side “B” of the same
substrate, which forms a second pattern having a second material onto side B of the substrate.
Sides A and B may have the same or different patterns, and/or may have the same or different
types of materials.
Additional embodiments pertains to multi-layer over-imprinting, and/or multi-layer
separated/offset substrate integration. In either/both of these approaches, a previously imprinted
pattern can be jetted upon and printed again. An adhesive can be jetted onto a first layer, with a
second substrate bonded to it (possibly with an airgap), and a subsequent jetting process can
deposit onto the second substrate and imprinted. Series-imprinted patterns can be bonded to
each other in sequence in a roll-to-roll process. It is noted that the approach of implementing
multi-layer over-imprinting may be used in conjunction with, or instead of, the multi-layer
separated/offset substrate integration approach. For multi-layer over-imprinting, a first imprint
material can be deposited and imprinted onto a substrate followed by deposition of a second
imprint material deposition, resulting in a composite, multi-layer structure having both a first
imprint material and a second imprint material. For multi-layer separated/offset substrate
integration, both a first substrate 1 and a second substrate 2 may be imprinted with the imprinting
material, and afterwards, substrate 1 and substrate 2 may be sandwiched and bonded, possibly
with offset features (also imprinted) that provide for, in one embodiment, an air-gap between the
active structures of substrate 2 and the back side of substrate 1. An imprinted spacer may be
used to create the air-gap.
According to yet another embodiment, disclosed is an approach to implement
variable volume deposition of materials distributed across the substrate, which may be dependent
upon an apriori knowledge of surface non-uniformity. This corrects for surface non-uniformity
of the substrate may result undesirable parallelism, causing poor optical performance. Variable
volume deposition of imprint material may be employed to provide a level distribution of imprint
material to be deposited independently of the underlying topography or physical feature set. For
example, the substrate can be pulled flat by vacuum chuck, and in situ metrology performed to
assess surface height, e.g., with low coherence or with laser based on-contact measurement
probes. The dispense volume of the imprint material can be varied depending upon the
measurement data to yield a more uniform layer upon replication. Any types of non-uniformity
may also be addressed by this embodiment of the invention, such as thickness variability and/or
the existence of pits, peaks or other anomalies or features associated with local positions on the
substrate.
[0016A] According to one embodiment, there is disclosed a method for manufacturing an
eyepiece comprising a first diffractive optical element, comprising: depositing a first layer onto
a first substrate, wherein the first layer comprises a first portion and a second portion, the first
portion is deposited to have a first depth onto a first region on the first substrate, the first portion
has a first optical index, the second portion is deposited to have a second depth onto a second
region on the first substrate, and the second portion has a second optical index different from the
first optical index; identifying a template having an imprint pattern formed thereon, the template
comprising a first set of depth structures and a second set of depth structures, the first set of depth
structures corresponding to the first depth of the first portion, and the second set of depth
structures corresponding to the second depth of the second portion; and imprinting the imprint
pattern into the first and the second portions on the first substrate with the template, wherein the
imprint pattern comprises a diffraction pattern for the first diffractive optical element, the first
portion is deposited to have the first depth according to at least a first optical function, the second
portion is deposited to have the second depth according to at least a second optical function,
before imprinting, and the first depth is different from the second depth.
[0016B] In one embodiment, the method further comprises imprinting, using at least the
template, the first and second portions that are respectively deposited onto the first and second
regions simultaneously to form a first pattern and a second pattern onto the first substrate,
wherein the imprint pattern comprises the first pattern and the second pattern, the template
imprints the first pattern with the first set of depth structures onto the first portion of the
materials, and the template imprints the second pattern with the second set of depth structures
onto the second portion of the materials.
[0016C] In one embodiment, the first pattern corresponds to a first diffraction grating pattern
and the second pattern corresponds to a second diffraction grating pattern.
[0016D] In one embodiment, the first function or the second function includes a first function of
in-coupling gratings, a second function of orthogonal pupil expander gratings, or a third function
of exit pupil expander gratings.
[0016E] In one embodiment, the method further comprises depositing, for the first diffractive
optical element of the eyepiece, a second layer above the first layer, wherein the second layer
comprises a first material having a first refractive index value in a first region of the second layer,
the second layer further comprises a second material having a second refractive index value in a
second region of the second layer, the first substrate comprises a third material having a third
refractive index value, and the first, second, and third refractive index values are selected based
at least in part upon a first requirement for a diffraction efficiency or a second requirement for a
field of view provided by the first diffractive optical element of the eye piece.
[0016F] In one embodiment, the method further comprises stacking, for the eyepiece, a second
diffractive optical element above a first negative lens that is further stacked above the first
diffractive optical element, wherein the first diffractive optical element is closer to a viewer's
eye than the second diffractive optical element and defines a first focal plane with a first focal
distance of optical infinity, the second diffractive element comprises a second substrate and
defines a second focal plane with a second focal distance that is smaller than the first focal
distance of the optical infinity, and the second diffractive element is separated from the first
diffractive element by the first lens.
[0016G] In one embodiment, the method further comprises stacking, for the eyepiece, a third
diffractive optical element above the second diffractive optical element, wherein the third
diffractive optical element comprises a third substrate and is disposed farther away from the
viewer's eye than the second diffractive optical element, the third diffractive optical element
defines a third focal plane with a third focal distance that is smaller than the second focal
distance, and the third diffractive optical element is separated from the second diffractive
element by a second lens.
[0016H] In one embodiment, the method further comprises disposing, for the eyepiece, a
compensation lens layer above the third diffractive optical element, wherein the compensation
lens layer is selected based at least in part upon an aggregate power of the first and the second
lens.
[0016I] In one embodiment, the first lens and the second lens create wavefront divergence to
define a different focal plane with a different focal distance that is smaller than the third focal
distance.
[0016J] In one embodiment, the method further comprises stacking, for the eyepiece, one or
more additional diffractive optical elements above the third diffractive optical element and away
from the viewer's eye, wherein the third diffractive element is separated from the one or more
additional diffractive optical elements by a separate lens, and the one or more diffractive optical
elements respectively define respective focal planes with one or more corresponding focal
distances that are smaller than the third focal distance.
[0016K] In one embodiment, the method further comprises disposing a compensation lens layer
above the one or more additional diffractive optical elements, wherein the compensation lens
layer is selected based at least in part upon an aggregate power of lenses separating diffractive
optical layers in the eyepiece.
[0016L] In one embodiment, at least two of the first diffractive optical element, the second
diffractive optical element, and the third diffractive optical element are multiplexed to create at
least one additional focal plane in addition to the first focal plane, the second focal plane, and
the third focal plane.
[0016M] In one embodiment, at least some of the first portion of the materials is deposited above
at least some of the second portion of the materials before imprinting the imprint pattern into the
first and the second portions.
[0016N] In one embodiment, the first diffractive optical element corresponds to a first set of one
or more projectors, and the second diffractive optical element corresponds to a second set of one
or more projectors.
[0016O] In one embodiment, the method further comprises imprinting a first pattern of the
imprint pattern into the first portion; and imprinting a second pattern into the second portion that
is different from the first pattern, wherein the imprint pattern comprises the first pattern and the
second pattern.
[0016P] In one embodiment, the first substrate having a first imprinted pattern is overlaid onto
a second substrate having a second imprinted pattern.
[0016Q] In one embodiment, the method further comprises depositing, for the first diffractive
optical element of the eyepiece, a second layer onto the first substrate, wherein the second layer
is deposited on an opposite surface opposing a surface onto which the first layer is deposited, the
second layer comprises a first material having a refractive index value in a first region of the
second layer, the first substrate comprises a different material having a different refractive index
value, and the first and the third refractive index values are selected based at least in part upon a
first requirement for a diffraction efficiency or a second requirement for a field of view provided
by the first diffractive optical element of the eyepiece.
[0016R] In one embodiment, the first refractive index value is smaller than the second refractive
index value and a substrate refractive index value of the first substrate, and the substrate
refractive index value is smaller than the second refractive index value.
[0016S] In one embodiment, the method further comprises determining a thickness value for the
first layer based at least in part upon a light incident angle for the first layer, the first refractive
index value, and the second refractive value.
It is noted that any of the preceding embodiments may be combined together.
Furthermore, additional and other objects, features, and advantages of the invention are
described in the detail description, figures and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates a user’s view of augmented reality (AR) through a wearable AR user
device, in one illustrated embodiment.
Fig. 2 illustrates a conventional stereoscopic 3-D simulation display system.
Fig. 3 illustrates an improved approach to implement a stereoscopic 3-D simulation
display system according to some embodiments of the invention.
Figs. 4A-4D illustrates various systems, subsystems, and components for addressing
the objectives of providing a high-quality, comfortably-perceived display system for human VR
and/or AR.
Fig. 5 illustrates a plan view of an example configuration of a system utilizing the
improved diffraction structure.
Fig. 6 illustrates a stacked waveguide assembly.
Fig. 7 illustrates a DOE.
Figs. 8 and 9 illustrate example diffraction patterns.
Figs. 10 and 11 illustrate two waveguides into which a beam is injected.
Fig. 12 illustrates a stack of waveguides.
Fig. 13A illustrates an example approach to implement a diffraction structure having
a waveguide substrate and a top grating surface, but without an underlayer.
Fig. 13B shows a chart of example simulation results.
Fig. 13C shows an annotated version of Fig. 13A.
Fig. 14A illustrates an example approach to implement a diffraction structure having
a waveguide substrate, an underlayer, and a top grating surface.
Fig. 14B illustrates an example approach to implement a diffraction structure having
a waveguide substrate, an underlayer, a grating surface, and a top surface.
Fig. 14C illustrates an example approach to implement stacking of diffraction
structures having a waveguide substrate, an underlayer, a grating surface, and a top surface.
Fig. 15A illustrates an example approach to implement a diffraction structure having
a high index waveguide substrate, a low index underlayer, and a low index top grating surface.
Fig. 15B shows charts of example simulation results.
Fig. 16A illustrates an example approach to implement a diffraction structure having
a low index waveguide substrate, a high index underlayer, and a low index top grating surface.
Fig. 16B shows charts of example simulation results.
Fig. 17A illustrates an example approach to implement a diffraction structure having
a low index waveguide substrate, a medium index underlayer, and a high index top grating
surface.
Fig. 17B shows a chart of example simulation results.
Fig. 18A-D illustrate modification of underlayer characteristics.
Fig. 19 illustrates an approach to implement precise, variable volume deposition of
imprint material on a single substrate.
Figure 20 illustrates an approach to implement directed, simultaneous deposition of
multiple different imprint materials in the same layer and imprint step according to some
embodiments.
Figs. 21A-B illustrates an example approach to implement two-sided imprint in the
context of total-internal reflection diffractive optical elements.
Fig. 22 illustrates a structure formed using the approach shown in Figs. 21A-B.
Fig. 23 illustrates an approach to implement multi-layer over-imprinting.
Fig. 24 illustrates an approach to implement multi-layer separated/offset substrate
integration.
Fig. 25 illustrates an approach to implement variable volume deposition of materials
distributed across the substrate to address surface non-uniformity.
DETAILED DESCRIPTION
According to some embodiments of the invention, a diffraction structure is employed
that includes an underlayer/intermediate layer that resides between a waveguide substrate and a
top grating surface. The top grating surface comprises a first material that corresponds to a first
refractive index value, the underlayer comprises a second material that corresponds to a second
refractive index value, and the substrate comprises a third material that corresponds to a third
refractive index value.
One advantage of this approach is that appropriate selection of the relative indices of
refraction for the three layers allows the structure to obtain a larger field of view for a greater
range of incident light, by virtue of the fact that the lowest total internal reflection angle is
reduced as the index of refraction is increased. Diffraction efficiencies can be increased,
allowing for “brighter” light outputs to the display(s) of image viewing devices.
A variety of combinations is available wherein an underlayer of one index is
combined with a top grating of another index, along with a substrate of a third index, and wherein
adjusting these relative values provides a lot of variation in dependence of diffraction efficiency
upon incidence angle. A layered waveguide with different layers of refractive indices is
presented. Various combinations and permutations are presented along with related performance
data to illustrate functionality. The benefits include increased angle, which provides an increased
output angle with the grating and therefore an increased field of view with the eyepiece. Further,
the ability to counteract the normal reduction in diffraction efficiency with angle is functionally
beneficial.
Display Systems According to Some Embodiments
This portion of the disclosure describes example display systems that may be used in
conjunction with the improved diffraction structure of the invention.
Fig. 2 illustrates a conventional stereoscopic 3-D simulation display system that
typically has a separate display 74 and 76 for each eye 4 and 6, respectively, at a fixed radial
focal distance 10 from the eye. This conventional approach fails to take into account many of
the valuable cues utilized by the human eye and brain to detect and interpret depth in three
dimensions, including the accommodation cue.
In fact, the typical human eye is able to interpret numerous layers of depth based
upon radial distance, e.g., able to interpret approximately 12 layers of depth. A near field limit
of about 0.25 meters is about the closest depth of focus; a far-field limit of about 3 meters means
that any item farther than about 3 meters from the human eye receives infinite focus. The layers
of focus get more and more thin as one gets closer to the eye; in other words, the eye is able to
perceive differences in focal distance that are quite small relatively close to the eye, and this
effect dissipates as objects fall farther away from the eye. At an infinite object location, a depth
of focus / dioptric spacing value is about 1/3 diopters.
Fig. 3 illustrates an improved approach to implement a stereoscopic 3-D simulation
display system according to some embodiments of the invention, where two complex images are
displayed, one for each eye 4 and 6, with various radial focal depths (12) for various aspects (14)
of each image may be utilized to provide each eye with the perception of three dimensional depth
layering within the perceived image. Since there are multiple focal planes (e.g., 12 focal planes)
between the eye of the user and infinity, these focal planes, and the data within the depicted
relationships, may be utilized to position virtual elements within an augmented reality scenario
for a user's viewing, because the human eye is constantly sweeping around to utilize the focal
planes to perceive depth. While this figure shows a specific number of focal planes at various
depths, it is noted that an implementation of the invention may use any number of focal planes
as necessary for the specific application desired, and the invention is therefore not limited to
devices having only to the specific number of focal planes shown in any of the figures in the
present disclosure.
Referring to Figs. 4A-4D, some general componentry options are illustrated
according to some embodiments of the invention. In the portions of the detailed description
which follow the discussion of Figs. 4A-4D, various systems, subsystems, and components are
presented for addressing the objectives of providing a high-quality, comfortably-perceived
display system for human VR and/or AR.
As shown in Fig. 4A, an AR system user (60) is depicted wearing a frame (64)
structure coupled to a display system (62) positioned in front of the eyes of the user. A speaker
(66) is coupled to the frame (64) in the depicted configuration and positioned adjacent the ear
canal of the user (in one embodiment, another speaker, not shown, is positioned adjacent the
other ear canal of the user to provide for stereo / shapeable sound control). The display (62) is
operatively coupled (68), such as by a wired lead or wireless connectivity, to a local processing
and data module (70) which may be mounted in a variety of configurations, such as fixedly
attached to the frame (64), fixedly attached to a helmet or hat (80) as shown in the embodiment
of Fig. 4B, embedded in headphones, removably attached to the torso (82) of the user (60) in a
backpack-style configuration as shown in the embodiment of Fig. 4C, or removably attached to
the hip (84) of the user (60) in a belt-coupling style configuration as shown in the embodiment
of Fig. 4D.
The local processing and data module (70) may comprise a power-efficient processor
or controller, as well as digital memory, such as flash memory, both of which may be utilized to
assist in the processing, caching, and storage of data a) captured from sensors which may be
operatively coupled to the frame (64), such as image capture devices (such as cameras),
microphones, inertial measurement units, accelerometers, compasses, GPS units, radio devices,
and/or gyros; and/or b) acquired and/or processed using the remote processing module (72)
and/or remote data repository (74), possibly for passage to the display (62) after such processing
or retrieval. The local processing and data module (70) may be operatively coupled (76, 78),
such as via a wired or wireless communication links, to the remote processing module (72) and
remote data repository (74) such that these remote modules (72, 74) are operatively coupled to
each other and available as resources to the local processing and data module (70).
In one embodiment, the remote processing module (72) may comprise one or more
relatively powerful processors or controllers configured to analyze and process data and/or image
information. In one embodiment, the remote data repository (74) may comprise a relatively
large-scale digital data storage facility, which may be available through the internet or other
networking configuration in a “cloud” resource configuration. In one embodiment, all data is
stored and all computation is performed in the local processing and data module, allowing fully
autonomous use from any remote modules.
Perceptions of Z-axis difference (i.e., distance straight out from the eye along the
optical axis) may be facilitated by using a waveguide in conjunction with a variable focus optical
element configuration. Image information from a display may be collimated and injected into a
waveguide and distributed in a large exit pupil manner using any suitable substrate-guided optics
methods known to those skilled in the art – and then variable focus optical element capability
may be utilized to change the focus of the wavefront of light emerging from the waveguide and
provide the eye with the perception that the light coming from the waveguide is from a particular
focal distance. In other words, since the incoming light has been collimated to avoid challenges
in total internal reflection waveguide configurations, it will exit in collimated fashion, requiring
a viewer’s eye to accommodate to the far point to bring it into focus on the retina, and naturally
be interpreted as being from optical infinity – unless some other intervention causes the light to
be refocused and perceived as from a different viewing distance; one suitable such intervention
is a variable focus lens.
In some embodiments, collimated image information is injected into a piece of glass
or other material at an angle such that it totally internally reflects and is passed into the adjacent
waveguide. The waveguide may be configured so that the collimated light from the display is
distributed to exit somewhat uniformly across the distribution of reflectors or diffractive features
along the length of the waveguide. Upon exit toward the eye, the exiting light is passed through
a variable focus lens element wherein, depending upon the controlled focus of the variable focus
lens element, the light exiting the variable focus lens element and entering the eye will have
various levels of focus (a collimated flat wavefront to represent optical infinity, more and more
beam divergence / wavefront curvature to represent closer viewing distance relative to the eye
58).
In a “frame sequential” configuration, a stack of sequential two-dimensional images
may be fed to the display sequentially to produce three-dimensional perception over time, in a
manner akin to the manner in which a computed tomography system uses stacked image slices
to represent a three-dimensional structure. A series of two-dimensional image slices may be
presented to the eye, each at a different focal distance to the eye, and the eye/brain would
integrate such a stack into a perception of a coherent three-dimensional volume. Depending
upon the display type, line-by-line, or even pixel-by-pixel sequencing may be conducted to
produce the perception of three-dimensional viewing. For example, with a scanned light display
(such as a scanning fiber display or scanning mirror display), then the display is presenting the
waveguide with one line or one pixel at a time in a sequential fashion.
Referring to Fig. 6, a stacked waveguide assembly (178) may be utilized to provide
three-dimensional perception to the eye/brain by having a plurality of waveguides (182, 184,
186, 188, 190) and a plurality of weak lenses (198, 196, 194, 192) configured together to send
image information to the eye with various levels of wavefront curvature for each waveguide
level indicative of focal distance to be perceived for that waveguide level. A plurality of displays
(200, 202, 204, 206, 208), or in another embodiment a single multiplexed display, may be
utilized to inject collimated image information into the waveguides (182, 184, 186, 188, 190),
each of which may be configured, as described above, to distribute incoming light substantially
equally across the length of each waveguide, for exit down toward the eye.
The waveguide (182) nearest the eye is configured to deliver collimated light, as
injected into such waveguide (182), to the eye, which may be representative of the optical infinity
focal plane. The next waveguide up (184) is configured to send out collimated light which passes
through the first weak lens (192; e.g., a weak negative lens) before it can reach the eye (58). The
first weak lens (192) may be configured to create a slight convex wavefront curvature so that the
eye/brain interprets light coming from that next waveguide up (184) as coming from a first focal
plane closer inward toward the person from optical infinity. Similarly, the third up waveguide
(186) passes its output light through both the first (192) and second (194) lenses before reaching
the eye (58). The combined optical power of the first (192) and second (194) lenses may be
configured to create another incremental amount of wavefront divergence so that the eye/brain
interprets light coming from that third waveguide up (186) as coming from a second focal plane
even closer inward toward the person from optical infinity than was light from the next
waveguide up (184).
The other waveguide layers (188, 190) and weak lenses (196, 198) are similarly
configured, with the highest waveguide (190) in the stack sending its output through all of the
weak lenses between it and the eye for an aggregate focal power representative of the closest
focal plane to the person. To compensate for the stack of lenses (198, 196, 194, 192) when
viewing/interpreting light coming from the world (144) on the other side of the stacked
waveguide assembly (178), a compensating lens layer (180) is disposed at the top of the stack to
compensate for the aggregate power of the lens stack (198, 196, 194, 192) below. Such a
configuration provides as many perceived focal planes as there are available waveguide/lens
pairings, again with a relatively large exit pupil configuration as described above. Both the
reflective aspects of the waveguides and the focusing aspects of the lenses may be static (i.e.,
not dynamic or electro-active). In an alternative embodiment they may be dynamic using
electro-active features as described above, enabling a small number of waveguides to be
multiplexed in a time sequential fashion to produce a larger number of effective focal planes.
Various diffraction configurations can be employed for focusing and/or redirecting
collimated beams. For example, passing a collimated beam through a linear diffraction pattern,
such as a Bragg grating, will deflect, or “steer”, the beam. Passing a collimated beam through a
radially symmetric diffraction pattern, or “Fresnel zone plate”, will change the focal point of the
beam. A combination diffraction pattern can be employed that has both linear and radial
elements produces both deflection and focusing of a collimated input beam. These deflection
and focusing effects can be produced in a reflective as well as transmissive mode.
These principles may be applied with waveguide configurations to allow for
additional optical system control. As shown in Fig. 7, a diffraction pattern (220), or “diffractive
optical element” (or “DOE”) has been embedded within a planar waveguide (216) such that as a
collimated beam is totally internally reflected along the planar waveguide (216), it intersects the
diffraction pattern (220) at a multiplicity of locations. The structure may also include another
waveguide (218) into which the beam may be injected (by a projector or display, for example),
with a DOE (221) embedded in this other waveguide (218),
Preferably, the DOE (220) has a relatively low diffraction efficiency so that only a
portion of the light of the beam is deflected toward the eye (58) with each intersection of the
DOE (220) while the rest continues to move through the planar waveguide (216) via total internal
reflection; the light carrying the image information is thus divided into a number of related light
beams that exit the waveguide at a multiplicity of locations and the result is a fairly uniform
pattern of exit emission toward the eye (58) for this particular collimated beam bouncing around
within the planar waveguide (216), as shown in Fig. 8. The exit beams toward the eye (58) are
shown in Fig. 8 as substantially parallel, because, in this case, the DOE (220) has only a linear
diffraction pattern. However, changes to this linear diffraction pattern pitch may be utilized to
controllably deflect the exiting parallel beams, thereby producing a scanning or tiling
functionality.
Referring to Fig. 9, with changes in the radially symmetric diffraction pattern
component of the embedded DOE (220), the exit beam pattern is more divergent, which would
require the eye to accommodation to a closer distance to bring it into focus on the retina and
would be interpreted by the brain as light from a viewing distance closer to the eye than optical
infinity.
Referring to Fig. 10, with the addition of the other waveguide (218) into which the
beam may be injected (by a projector or display, for example), a DOE (221) embedded in this
other waveguide (218), such as a linear diffraction pattern, may function to spread the light
across the entire larger planar waveguide (216), which functions to provide the eye (58) with a
very large incoming field of incoming light that exits from the larger planar waveguide (216),
e.g., a large eye box, in accordance with the particular DOE configurations at work.
The DOEs (220, 221) are depicted bisecting the associated waveguides (216, 218)
but this need not be the case; they could be placed closer to, or upon, either side of either of the
waveguides (216, 218) to have the same functionality. Thus, as shown in Fig. 11, with the
injection of a single collimated beam, an entire field of cloned collimated beams may be directed
toward the eye (58). In addition, with a combined linear diffraction pattern / radially symmetric
diffraction pattern scenario such as that discussed above, a beam distribution waveguide optic
(for functionality such as exit pupil functional expansion; with a configuration such as that of
Fig. 11, the exit pupil can be as large as the optical element itself, which can be a very significant
advantage for user comfort and ergonomics) with Z-axis focusing capability is presented, in
which both the divergence angle of the cloned beams and the wavefront curvature of each beam
represent light coming from a point closer than optical infinity.
In one embodiment, one or more DOEs are switchable between “on” states in which
they actively diffract, and “off” states in which they do not significantly diffract. For instance, a
switchable DOE may comprise a layer of polymer dispersed liquid crystal, in which
microdroplets comprise a diffraction pattern in a host medium, and the refractive index of the
microdroplets can be switched to substantially match the refractive index of the host material (in
which case the pattern does not appreciably diffract incident light) or the microdroplet can be
switched to an index that does not match that of the host medium (in which case the pattern
actively diffracts incident light). Further, with dynamic changes to the diffraction terms, a beam
scanning or tiling functionality may be achieved. As noted above, it is desirable to have a
relatively low diffraction grating efficiency in each of the DOEs (220, 221) because it facilitates
distribution of the light, and also because light coming through the waveguides that is desirably
transmitted (for example, light coming from the world 144 toward the eye 58 in an augmented
reality configuration) is less affected when the diffraction efficiency of the DOE that it crosses
(220) is lower – so a better view of the real world through such a configuration is achieved.
Configurations such as those illustrated herein preferably are driven with injection of
image information in a time sequential approach, with frame sequential driving being the most
straightforward to implement. For example, an image of the sky at optical infinity may be
injected at time1 and the diffraction grating retaining collimation of light may be utilized.
Thereafter, an image of a closer tree branch may be injected at time2 while a DOE controllably
imparts a focal change, say one diopter or 1 meter away, to provide the eye/brain with the
perception that the branch light information is coming from the closer focal range. This kind of
paradigm can be repeated in rapid time sequential fashion such that the eye/brain perceives the
input to be all part of the same image. This is just a two focal plane example -- preferably the
system will include more focal planes to provide a smoother transition between objects and their
focal distances. This kind of configuration generally assumes that the DOE is switched at a
relatively low speed (i.e., in sync with the frame-rate of the display that is injecting the images
– in the range of tens to hundreds of cycles/second).
The opposite extreme may be a configuration wherein DOE elements can shift focus
at tens to hundreds of MHz or greater, which facilitates switching of the focus state of the DOE
elements on a pixel-by-pixel basis as the pixels are scanned into the eye (58) using a scanned
light display type of approach. This is desirable because it means that the overall display frame-
rate can be kept quite low; just low enough to make sure that “flicker” is not a problem (in the
range of about 60-120 frames/sec).
In between these ranges, if the DOEs can be switched at KHz rates, then on a line-
by-line basis the focus on each scan line may be adjusted, which may afford the user with a
visible benefit in terms of temporal artifacts during an eye motion relative to the display, for
example. For instance, the different focal planes in a scene may, in this manner, be interleaved,
to minimize visible artifacts in response to a head motion (as is discussed in greater detail later
in this disclosure). A line-by-line focus modulator may be operatively coupled to a line scan
display, such as a grating light valve display, in which a linear array of pixels is swept to form
an image; and may be operatively coupled to scanned light displays, such as fiber-scanned
displays and mirror-scanned light displays.
A stacked configuration, similar to those of Fig. 6, may use dynamic DOEs to provide
multi-planar focusing simultaneously. For example, with three simultaneous focal planes, a
primary focus plane (based upon measured eye accommodation, for example) could be presented
to the user, and a + margin and – margin (i.e., one focal plane closer, one farther out) could be
utilized to provide a large focal range in which the user can accommodate before the planes need
be updated. This increased focal range can provide a temporal advantage if the user switches to
a closer or farther focus (i.e., as determined by accommodation measurement); then the new
plane of focus could be made to be the middle depth of focus, with the + and – margins again
ready for a fast switchover to either one while the system catches up.
Referring to Fig. 12, a stack (222) of planar waveguides (244, 246, 248, 250, 252) is
shown, each having a reflector (254, 256, 258, 260, 262) at the end and being configured such
that collimated image information injected in one end by a display (224, 226, 228, 230, 232)
bounces by total internal reflection down to the reflector, at which point some or all of the light
is reflected out toward an eye or other target. Each of the reflectors may have slightly different
angles so that they all reflect exiting light toward a common destination such as a pupil. Lenses
(234, 236, 238, 240, 242) may be interposed between the displays and waveguides for beam
steering and/or focusing.
As discussed above, an object at optical infinity creates a substantially planar
wavefront, while an object closer, such as 1m away from the eye, creates a curved wavefront
(with about 1m convex radius of curvature). The eye’s optical system needs to have enough
optical power to bend the incoming rays of light so that they end up focused on the retina (convex
wavefront gets turned into concave, and then down to a focal point on the retina). These are
basic functions of the eye.
In many of the embodiments described above, light directed to the eye has been
treated as being part of one continuous wavefront, some subset of which would hit the pupil of
the particular eye. In another approach, light directed to the eye may be effectively discretized
or broken down into a plurality of beamlets or individual rays, each of which has a diameter less
than about 0.5mm and a unique propagation pathway as part of a greater aggregated wavefront
that may be functionally created with the an aggregation of the beamlets or rays. For example,
a curved wavefront may be approximated by aggregating a plurality of discrete neighboring
collimated beams, each of which is approaching the eye from an appropriate angle to represent
a point of origin that matches the center of the radius of curvature of the desired aggregate
wavefront.
When the beamlets have a diameter of about 0.5mm or less, it is as though it is coming
through a pinhole lens configuration, which means that each individual beamlet is always in
relative focus on the retina, independent of the accommodation state of the eye—however the
trajectory of each beamlet will be affected by the accommodation state. For instance, if the
beamlets approach the eye in parallel, representing a discretized collimated aggregate wavefront,
then an eye that is correctly accommodated to infinity will deflect the beamlets to all converge
upon the same shared spot on the retina, and will appear in focus. If the eye accommodates to,
say, 1 m, the beams will be converged to a spot in front of the retina, cross paths, and fall on
multiple neighboring or partially overlapping spots on the retina—appearing blurred.
If the beamlets approach the eye in a diverging configuration, with a shared point of
origin 1 meter from the viewer, then an accommodation of 1 m will steer the beams to a single
spot on the retina, and will appear in focus; if the viewer accommodates to infinity, the beamlets
will converge to a spot behind the retina, and produce multiple neighboring or partially
overlapping spots on the retina, producing a blurred image. Stated more generally, the
accommodation of the eye determines the degree of overlap of the spots on the retina, and a
given pixel is “in focus” when all of the spots are directed to the same spot on the retina and
“defocused” when the spots are offset from one another. This notion that all of the 0.5mm
diameter or less beamlets are always in focus, and that they may be aggregated to be perceived
by the eyes/brain as though they are substantially the same as coherent wavefronts, may be
utilized in producing configurations for comfortable three-dimensional virtual or augmented
reality perception.
In other words, a set of multiple narrow beams may be used to emulate what is going
on with a larger diameter variable focus beam, and if the beamlet diameters are kept to a
maximum of about 0.5mm, then they maintain a relatively static focus level, and to produce the
perception of out-of-focus when desired, the beamlet angular trajectories may be selected to
create an effect much like a larger out-of-focus beam (such a defocussing treatment may not be
the same as a Gaussian blur treatment as for the larger beam, but will create a multimodal point
spread function that may be interpreted in a similar fashion to a Gaussian blur).
In some embodiments, the beamlets are not mechanically deflected to form this
aggregate focus effect, but rather the eye receives a superset of many beamlets that includes both
a multiplicity of incident angles and a multiplicity of locations at which the beamlets intersect
the pupil; to represent a given pixel from a particular viewing distance, a subset of beamlets from
the superset that comprise the appropriate angles of incidence and points of intersection with the
pupil (as if they were being emitted from the same shared point of origin in space) are turned on
with matching color and intensity, to represent that aggregate wavefront, while beamlets in the
superset that are inconsistent with the shared point of origin are not turned on with that color and
intensity (but some of them may be turned on with some other color and intensity level to
represent, e.g., a different pixel).
Referring now to Fig. 5, an example embodiment 800 of the AR system that uses an
improved diffraction structure will now be described. The AR system generally includes an
image generating processor 812, at least one FSD 808 (fiber scanning device), FSD circuitry
810, a coupling optic 832, and at least one optics assembly (DOE assembly 802) having stacked
waveguides with the improved diffraction structure described below. The system may also
include an eye-tracking subsystem 806. As shown in Fig. 5, the FSD circuitry may comprise
circuitry 810 that is in communication with the image generation processor 812 having a maxim
chip CPU 818, a temperature sensor 820, a piezo-electrical drive/transducer 822, a red laser 826,
a blue laser 828, and a green laser 830 and a fiber combiner that combines all three lasers 826,
828 and 830. It is noted that other types of imaging technologies are also usable instead of FSD
devices. For example, high-resolution liquid crystal display (“LCD”) systems, a backlighted
ferroelectric panel display, and/or a higher-frequency DLP system may all be used in some
embodiments of the invention.
The image generating processor is responsible for generating virtual content to be
ultimately displayed to the user. The image generating processor may convert an image or video
associated with the virtual content to a format that can be projected to the user in 3D. For
example, in generating 3D content, the virtual content may need to be formatted such that
portions of a particular image are displayed on a particular depth plane while other are displayed
at other depth planes. Or, all of the image may be generated at a particular depth plane. Or, the
image generating processor may be programmed to feed slightly different images to right and
left eye such that when viewed together, the virtual content appears coherent and comfortable to
the user’s eyes. In one or more embodiments, the image generating processor 812 delivers
virtual content to the optics assembly in a time-sequential manner. A first portion of a virtual
scene may be delivered first, such that the optics assembly projects the first portion at a first
depth plane. Then, the image generating processor 812 may deliver another portion of the same
virtual scene such that the optics assembly projects the second portion at a second depth plane
and so on. Here, the Alvarez lens assembly may be laterally translated quickly enough to
produce multiple lateral translations (corresponding to multiple depth planes) on a frame-to
frame basis.
The image generating processor 812 may further include a memory 814, a CPU 818,
a GPU 816, and other circuitry for image generation and processing. The image generating
processor may be programmed with the desired virtual content to be presented to the user of the
AR system. It should be appreciated that in some embodiments, the image generating processor
may be housed in the wearable AR system. In other embodiments, the image generating
processor and other circuitry may be housed in a belt pack that is coupled to the wearable optics.
The AR system also includes coupling optics 832 to direct the light from the FSD to
the optics assembly 802. The coupling optics 832 may refer to one more conventional lenses
that are used to direct the light into the DOE assembly. The AR system also includes the eye-
tracking subsystem 806 that is configured to track the user’s eyes and determine the user’s focus.
In one or more embodiments, software blurring may be used to induce blurring as
part of a virtual scene. A blurring module may be part of the processing circuitry in one or more
embodiments. The blurring module may blur portions of one or more frames of image data being
fed into the DOE. In such an embodiment, the blurring module may blur out parts of the frame
that are not meant to be rendered at a particular depth frame.
Example approaches that can be used to implement the above image display systems, and
components therein, are described in U.S. Utility Patent Application Serial No. 14/555,585.
Improved Diffraction Structure
As stated above, a diffraction pattern can be formed onto a planar waveguide, such
that as a collimated beam is totally internally reflected along the planar waveguide, the beam
intersects the diffraction pattern at a multiplicity of locations. This arrangement can be stacked
to provide image objects at multiple focal planes within a stereoscopic 3-D simulation display
system according to some embodiments of the invention.
Fig. 13A illustrates one possible approach that can be taken to implement a structure
1300 of a waveguide 1302 (also referred to herein as a “light guide”, “substrate”, or “waveguide
substrate”), where outcoupling gratings 1304 are directly formed onto the top surface of the
waveguide 1302, e.g., as a combined monolithic structure and/or both formed of the same
materials (even if not constructed out of the same monolithic structure). In this approach, the
index of refraction of the gratings material is the same as the index of refraction of the waveguide
1302. The index of refraction n (or “refractive index”) of a material describes how light
propagates through that medium, and is defined as n = c/v. where c is the speed of light in vacuum
and v is the phase velocity of light in the medium. The refractive index determines how much
light is bent, or refracted, when entering a material.
Fig. 13B shows a chart 1320 of example simulation results for a single polarization
of the efficiency of the light coming out of the structure 1300 as a function of the angle at which
the light is propagating within the waveguide. This chart shows that the diffraction efficiency
of the outcoupled light for structure 1300 decreases at higher angles of incidence. As can be
seen, at an angle of about 43 degrees, the efficiency drops relatively quickly on the depicted plot
due to total internal reflectance variation based on incident angle in a medium with uniform
index of refraction.
Therefore, it is possible that the usable range of configuration 1300 is somewhat
limited and therefore undesirable, as the spacing of bounces may decrease at higher angles of
incidence, which may further reduce the brightness seen by an observer at those angles. The
diffraction efficiency is lower at the most shallow angles of incidence, which is not entirely
desirable, because the bounce spacing (see Fig. 13C) between interactions with the top surface
is fairly far apart, and light has fairly few opportunities to couple out. Thus, a dimmer signal
with fewer outcoupled samples will result from this arrangement, with this problem being
compounded by the grating having lower diffraction efficiencies at these high angles with this
polarization orientation. It is noted that as used herein and in the figures, “1T” refers to the 1
transmitted diffracted order.
In some embodiments of waveguide-based optical systems or substrate guided optical
systems, such as those described above, different pixels in a substrate-guided image are
represented by beams propagating at different angles within the waveguide, where light
propagates along the waveguide by total internal reflection (TIR). The range of beam angles that
remain trapped in a waveguide by TIR is a function of the difference in refractive index between
the waveguide and the medium (e.g., air) outside the waveguide; the higher the difference in
refractive index, the larger the number of beam angles. In certain embodiments, the range of
beam angles propagating along the waveguide correlates with the field of view of the image
coupled out of the face of the waveguide by a diffractive element, and with the image resolution
supported by the optical system. Additionally, the angle range in which total internal reflection
occurs is dictated by the index of refraction of the waveguide – in some embodiments a minimum
of about 43 degrees and a practical maximum of approximately 83 degrees, thus a 40 degree
range.
Fig. 14A illustrates an approach to address this issue according to some embodiments
of the invention, where structure 1400 includes an intermediate layer 1406 (referred to herein as
“underlayer 1406”) that resides between the substrate 1302 and the top grating surface 1304.
The top surface 1304 comprises a first material that corresponds to a first refractive index value,
the underlayer 1406 comprises a second material that corresponds to a second refractive index
value, and the substrate 1302 comprises a third material that corresponds to a third refractive
index value. It is noted that any combination of same or different materials may be employed to
implement each of these portions of structure 1400, e.g., where all three materials are different
(and all three correspond to different refractive index values), or where two of the layers share
the same material (e.g., where two of the three materials are the same and therefore share a
common reflective index value that differs from the refractive index value of the third material).
Any combination of refractive index values may be employed. For example, one embodiment
comprises a low refractive index for the underlayer, with higher index values for the surface
grating and the substrate. Other example configurations are described below having other
illustrative combinations of refractive index values. Any suitable set of materials may be used
to implement structure 1500. For example, polymers, glass, and sapphire are all examples of
materials that can be selected to implement any of the layers of structure 1400.
As shown in Fig. 15A, in some embodiments it may be desirable to implement a
structure 1500 that uses a relatively higher refractive index substrate as waveguide substrate
1302, with a relatively lower refractive index underlayer 1406 and relatively lower refractive
index top grating surface 1304. This is because one may be able to obtain a larger field of view
by virtue of the fact that the lowest total internal reflection angle is reduced as the index of
refraction is increased through the relationship n1*sin(theta1)=n2*sin(90). For a substrate of
index 1.5, the critical angle is 41.8 degrees; however, for a substrate index of 1.7, the critical
angle is 36 degrees.
Gratings formed on higher index substrates may be utilized to couple light out even
if they themselves have a lower index of refraction, so long as the layer of material comprising
the grating is not too thick between the grating and the substrate. This is related to the fact that
one can have a more broad range of angles for total internal reflection (“TIR”) with such a
configuration. In other words, the TIR angle drops to lower values with such a configuration.
In addition, it is noted that many of the current etching processes may not be well suited for
extending to high-index glasses. It is desirable in some embodiments to replicate an outcoupling
layer reliably and inexpensively.
The configuration of the underlayer 1406 may be adjusted to alter the performance
characteristics of structure 1500, e.g., by changing the thickness of the underlayer 1406. The
configuration of Fig. 15A (a construct including a grating structure 1304 on top comprising a
relatively low index material, with an associated lower index underlayer 1406, and which also
includes an associated high-index light guiding substrate 1302) may be modelled to result in data
such as that depicted in Fig. 15B. Referring to this figure, the plot 1502a on the left is related to
a configuration with zero-thickness underlayer 1502. The middle plot 1502b shows data for a
0.05 micron thickness underlayer 1502. The right plot 1502c shows data for a 0.1 micron
thickness underlayer 1502.
As shown by the data in these plots, as the underlayer thickness is increased, the
diffraction efficiency as a function of incident angle becomes much more nonlinear and
suppressed at high angles, which may not be desirable. Thus in this case, control of the
underlayer is an important functional input. However, it should be noted that with a zero-
thickness underlayer and only grating features themselves possessing the lower index, the range
of angles supported by the structure is governed by the TIR condition in the higher index base
material, rather than the lower index grating feature material.
Referring to Fig. 16A, an embodiment of a structure 1600 is illustrated featuring a
relatively high index underlayer 1406 on a lower index substrate 1302, with a top surface
diffraction grating 1304 having a refractive index lower than the underlayer 1406 and
comparable to, but not necessarily equal to, the refractive index of the substrate 1302. For
example, the top surface grating may correspond to a refractive index of 1.5, the underlayer may
correspond to a refractive index of 1.84, and the substrate may correspond to a refractive index
of 1.5. Assume for this example that the period is 0.43 um and lambda corresponds to 0.532 um.
Simulations related to such a configuration are presented in Fig. 16B. As shown in
this figure in chart 1602a, with a 0.3 micron thick underlayer 1406, diffraction efficiency falls
off like the previously described configuration, but then starts to rise up at the higher end of the
angular range. This is also true for the 0.5 micron thick underlayer 1406 configuration, as shown
in chart 1602b. It is beneficial in each of these (0.3 micron, 0.5 micron) configurations, that the
efficiency is relatively high at the higher extremes of the angular range; such functionality may
tend to counteract the more sparse bounce spacing concern discussed above. Also shown in this
figure is chart 1602c for an embodiment featuring a 90 degree rotated polarization case, where
the diffraction efficiency is lower as might be expected, but shows desirable behavior in that it
provides greater efficiency at steeper angles as compared to shallower angles.
Indeed, in some embodiments, diffraction efficiency versus angles may increase at
high angles. This may be a desirable feature for some embodiments since it helps to compensate
for the lower bounce spacing that may occur at higher propagation angles. Therefore, the
structural configuration of Fig. 16A may be preferable in embodiments where it is desirable to
compensate for the lower bounce spacing (which occurs with higher propagation angles), since
it promotes diffraction efficiency versus angle increasing at higher angles, which is desirable
relative to the aforementioned monolithic configurations.
Referring to Fig. 17A, another structure 1700 is depicted wherein an underlayer 1406
has a refractive index substantially higher than the refractive index of the substrate 1302. A
grating structure 1304 is on top, and has a refractive index that is also higher than the refractive
index of the underlayer 1406. For example, the top surface grating may correspond to a
refractive index of 1.86, the underlayer may correspond to a refractive index of 1.79, and the
substrate may correspond to a refractive index of 1.5. As before, assume for this example that
the period is 0.43 um and lambda corresponds to 0.532 um.
Referring to Fig. 17B, chart 1702 shows simulation data is illustrated for the structure
1700 of Fig. 17A. As shown in chart 1702, the plot of the resulting diffraction efficiency versus
incident angle demonstrates a desirable general behavior to assist in compensating for the
aforementioned lower bounce spacing at relatively high incident angles and possessing
reasonable diffraction efficiency across a greater range of angles in general.
It is noted that the underlayer 1406 does not need to be uniform across the entire
substrate. Any characteristic of the underlayer 1406 may be varied at different locations of the
substrate, such as variances in the thickness, composition, and/or index of refraction of the
underlayer 1406. One possible reason for varying the characteristics of the underlayer 1406 is
to promote uniform display characteristics in the presence of known variations in either the
display image and/or non-uniform transmission of light within the display system.
For example, as shown in Fig. 18A, consider if the waveguide structure receives
incoming light at a single incoupling location 1802 on the waveguide. As the incoming light is
injected into the waveguide 1302, less and less of that light will be remain as it progresses along
the length of the waveguide 1302. This means that the output light near the incoupling location
1802 may end up appearing “brighter” than output light farther along the length of the waveguide
1302. If the underlayer 1406 is uniform along the entire length of the waveguide 1302, then the
optical effects of the underlayer 1406 may reinforce this uneven brightness level across the
substrate.
The characteristics of the underlayer 1406 can be adjusted across the substrate 1302
to make the output light more uniform. Fig. 18B illustrates an approach whereby the thickness
of the underlayer 1406 is varied across the length of the waveguide substrate 1302, where the
underlayer 1406 is thinner near the incoupling location 1802 and thicker at farther distances
away from location 1802. In this manner, the effect of the underlayer 1406 to promote greater
diffraction efficiency can at least partially ameliorate the effects of light losses along the length
of the waveguide substrate 1302, thereby promoting more uniform light output across the entirety
of the structure.
Fig. 18C illustrates an alternate approach where the thickness of the underlayer 1406
is not varied, but the refractive index of the underlayer 1406 varies across the substrate 1302.
For example, to address the issue that output light near location 1802 tends to be brighter than
locations farther away from location 1802, the index of refraction for the underlayer 1406 can
be configured to be the same or similar to the substrate 1302 close to location 1802, but to have
an increasing difference in those index values at locations farther away from location 1802. The
composition of the underlayer 1406 material can be varied at different location to effect the
different refractive index values. Fig. 18D illustrates a hybrid approach, whereby both the
thickness and the refractive index of the underlayer 1406 is varied across the substrate 1302. It
is noted that this same approach can be taken to vary the thickness and/or refractive index of the
top grating surface 1304 and/or the substrate 1302 in conjunction with, or instead of, varying the
underlayer 1406.
Thus a variety of combinations is available wherein an underlayer 1406 of one index
is combined with a top grating 1304 of another index, along with a substrate 1302 of a third
index, and wherein adjusting these relative values provides a lot of variation in dependence of
diffraction efficiency upon incidence angle. A layered waveguide with different layers of
refractive indices is presented. Various combinations and permutations are presented along with
related performance data to illustrate functionality. The benefits include increased angle, which
provides an increased output angle with the grating 1304 and therefore an increased field of view
with the eyepiece. Further, the ability to counteract the normal reduction in diffraction efficiency
with angle is functionally beneficial.
Fig. 14B illustrates an embodiment where another layer of material 1409 (top surface)
is placed above the grating layer 1304. Layer 1409 can be configurably implemented to address
different design goals. For example, layer 1409 can form an interstitial layer between multiple
stacked diffraction structures 1401a and 1401b, e.g., as shown in Fig. 14C. As shown in Fig.
14C, this interstitial layer 1409 can be employed to remove any air space/gap and provide a
support structure for the stacked diffraction components. In this use case, the layer 1409 can be
formed from a material having a relatively low index of refraction, e.g., at around 1.1 or 1.2.
Although not shown in this figure, other layers (such as weak lenses) may also be placed between
the diffraction structures 1401a and 1401b.
In addition, layer 1409 can be formed from a material having a relatively high index
of refraction. In this situation, it is the gratings on the layer 1409 that would provide the
diffraction effects for all or a substantial amount of the incident light, rather than the grating
surface 1304.
As is clear, different relative combinations of refractive index values can be selected
for the different layers, including layer 1409, to achieve desired optical effects and results.
Such structures may be manufactured using any suitable manufacturing techniques.
Certain high-refractive index polymers such as one known as “MR 174” may be directly
embossed, printed, or etched to produce desired patterned structures, although there may be
challenges related to cure shrinkage and the like of such layers. Thus, in another embodiment,
another material may be imprinted, embossed, or etched upon a high-refractive index polymer
layer (i.e., such as a layer of MR 174) to produce a functionally similar result. Current state of
the art printing, etching (i.e., which may include resist removal and patterning steps similar to
those utilized in conventional semiconductor processes), and embossing techniques may be
utilized and/or combined to accomplish such printing, embossing, and/or etching steps. Molding
techniques, similar to those utilized, for example, in the production of DVDs, may also be
utilized for certain replication steps. Further, certain jetting or deposition techniques utilized in
printing and other deposition processes may also be utilized for depositing certain layers with
precision.
The following portion of the disclosure will now describe improved approaches to
implement the formation patterns onto substrates for diffraction, wherein imprinting of deposited
imprint materials is performed according to some embodiments of the invention. These
approaches allow for very precise distribution of imprint materials, as well as very precise
formation of different imprint patterns onto any number of substrate surfaces. It is noted that the
following description can be used in conjunction with, and to implement, the grating
configurations described above. However, it is expressly noted that the inventive deposition
approach may also be used in conjunction with other configurations as well.
According to some embodiments, patterned distribution (e.g., patterned inkjet
distribution) of imprint materials are performed to implement the deposition of imprint materials
onto a substrate. This approach of using patterned ink-jet distribution allows for very precise
volume control over the materials to be deposited. In addition, this approach can serve to provide
a smaller, more uniform base layer beneath a grating surface – and as discussed above, the base
thickness of a layer can have a significant effect on the performance of an eyepiece/optical
device.
Fig. 19 illustrates an approach to implement precise, variable volume deposition of
imprint material on a single substrate. As shown in the figure, a template 1902 is provided
having a first set of deeper depth structures 1904 and a second set of shallower (e.g., standard)
depth structures 1906. When depositing imprint materials onto an imprint receiver 1908, a
relatively higher volume of imprint materials 1910 is deposited in correspondence to the portion
of the template with the deeper depth structures 1904 of the template 1902. In contrast, a
relatively lower volume of imprint materials 1912 is deposited in conjunction with the shallower
depth structures 1906 of the template 1902. The template then is used to imprint the first and
second set of depth structures into the imprint materials, forming respective structures having
different depths and/or patterns within the imprint materials. This approach therefore permits
simultaneous formation of different features onto the imprint receiver 1908.
This approach can be taken to create distributions that are purposefully non-uniform
for structures with different depths and/or feature parameters, e.g., where the feature structures
are on the same substrate and have different thicknesses. This can be used, for example, to create
spatially distributed volumes of imprint material that enable simultaneous imprint of structures
of variable depth with the same underlayer thickness.
The bottom of Fig. 19 illustrates a structure 1920 that is formed with the deposition
technique/apparatus described above, where the underlayer 1922 has a uniform thickness despite
pattern depth and volume differentials. It can be seen that imprint materials have been deposited
with non-uniform thicknesses in structure 1920. Here, the top layer 1924 includes a first portion
1926 having a first set of layer thicknesses, while a second portion 1928 has a second set of layer
thicknesses. In this example, portion 1926 corresponds to a thicker layer as compared to the
standard/shallower thickness of portion 1928. It is noted, however, that any combination of
thicknesses may be constructed using the inventive concept, where thicknesses that are
either/both thicker and/or thinner than standard thicknesses are formed onto an underlayer.
This capability can also be used to deposit larger volumes of material to serve as, for
example, spacer elements to aid in the construction of a multi-layer diffractive optical element,
for example.
Some embodiments pertain to an approach to implement simultaneous deposition of
multiple types of imprint materials onto a substrate. This permits materials having optical
properties to be simultaneously deposited across multiple portions of the substrate at the same
time. This approach also provides the ability to tune local areas associated with specific
functions, e.g., to act as in-coupling grating, orthogonal pupil expander (OPE) gratings, or exit
pupil expander (EPE) gratings.
Figure 20 illustrates an approach to implement directed, simultaneous deposition of
multiple different imprint materials in the same layer and imprint step according to some
embodiments. As shown in the figure, a template 2002 is provided to imprint patterns into the
different types of imprint materials 2010 and 2012 on the imprint receiver 2008. Materials 2010
and 2012 may comprise the same material having different optical properties (e.g., two variants
of the same material having differing indices of refraction) or two entirely different materials.
Any optical property of the materials can be considered and selected when employing
this technique. For example, as shown in the embodiment of Fig. 20, material 2010 corresponds
to a high index of refraction material that is deposited in one section of the imprint receiver 2008,
while at the same time, material 2012 corresponding to a lower index of refraction material that
is deposited in the area of a second section.
As shown in the resulting structure 2020, this forms a multi-function diffractive
optical element having a high index of refraction portion 2026 and a lower index of refraction
portion 2028. In this case, high index portion 2026 pertaining to a first function and portion
2028 pertaining to a second function were imprinted simultaneously.
While this example illustratively identifies the refractive index of the materials as the
optical property to “tune” when simultaneously depositing the materials, it is noted that other
optical properties may also be considered when identifying the type of materials to deposit in
different portions of the structure. For example, opacity and absorption are other properties that
can be used to identify materials for deposition in different portions of the structure to tune the
local properties of the final product.
In addition, one type of material may be deposited above/below another material
before imprinting. For example, one index of refraction material may be deposited directly
below a second index of refraction material just prior to imprinting, producing a gradient index
to form a diffractive optical element. This can be used, for example, to implement the structure
shown in Fig. 17A (or any of the other pertinent structures described above or in the figures).
According to another embodiment, multi-sided imprinting may be employed to
imprint multiple sides of an optical structure. This permits imprinting to occur on different sides
of an optical element, to implement multiplexing of functions through a base layer volume. In
this way, different eyepiece functions can be implemented without adversely affecting grating
structure function.
Figs. 21A-B illustrates an example approach to implement two-sided imprint in the
context of total-internal reflection diffractive optical elements. As illustrated in Fig. 21A, a first
template 2102a may be used to produce one imprint on side “A” of the substrate/imprint receiver
2108. This forms a first pattern 2112 having a first material onto side A of the structure.
As illustrated in Fig. 21B, template 2102b may be used to produce a second imprint
on side “B” of the same substrate. This forms a second pattern 2114 having a second material
onto side B of the substrate.
It is noted that sides A and B may have the same or different patterns, and/or may
have the same or different types of materials. In addition, the pattern on each side may comprise
varying layer thicknesses (e.g., using the approach of Fig. 19) and/or have different material
types on the same side (e.g., using the approach of Fig. 20).
As shown in Fig. 22, a first pattern 2112 has been imprinted onto side A and a second
pattern 2114 onto the opposite side B of the substrate 2108. The compound function of the
resulting two-sided imprinted element 2200 can now be realized. In particular, when input light
is applied to the two-sided imprinted element 2200, some the light exits from the element 2200
to implement a first function 1 while other light exits to implement a second function 2.
Additional embodiments pertain to multi-layer over-imprinting, and/or multi-layer
separated/offset substrate integration. In either/both of these approaches, a previously imprinted
pattern can be jetted upon and printed again. An adhesive can be jetted onto a first layer, with a
second substrate bonded to it (possibly with an airgap), and a subsequent jetting process can
deposit onto the second substrate and imprinted. Series-imprinted patterns can be bonded to
each other in sequence in a roll-to-roll process. It is noted that the approach of implementing
multi-layer over-imprinting may be used in conjunction with, or instead of, the multi-layer
separated/offset substrate integration approach.
Fig. 23 illustrates an approach to implement multi-layer over-imprinting. Here, a
first imprint material 2301 can be deposited onto a substrate 2308 and imprinted. This is
followed by deposition (and possible imprinting) of a second imprint material 2302. This results
in a composite, multi-layer structure having both a first imprint material 2301 and a second
imprint material 2302. In one embodiment, subsequent imprinting may be implemented for the
second imprint material 2302. In an alternate embodiment, subsequent imprinting is not
implemented for the second imprint material 2302.
Fig. 24 illustrates an approach to implement multi-layer separated/offset substrate
integration. Here, both a first substrate 1 and a second substrate 2 may be deposited with the
imprinting material and then imprinted. Afterwards, substrate 1 and substrate 2 may be
sandwiched and bonded, possibly with offset features (also imprinted) that provide for, in one
embodiment, an air-gap 2402 between the active structures of Substrate 2 and the back side of
substrate 1. An imprinted spacer 2404 may be used to create the airgap 2402.
According to yet another embodiment, disclosed is an approach to implement
variable volume deposition of materials distributed across the substrate, which may be dependent
upon an apriori knowledge of surface non-uniformity. To explain, consider the substrate 2502
shown in Fig. 25. As shown, the surface non-uniformity of the substrate 2502 may result
undesirable parallelism, causing poor optical performance. In this case, the substrate 2502 (or a
previously imprinted layer) may be measured for variability.
Variable volume deposition of imprint material may be employed to provide a level
distribution of imprint material to be deposited independently of the underlying topography or
physical feature set. For example, the substrate can be pulled flat by vacuum chuck, and in situ
metrology performed to assess surface height, e.g., with low coherence or with laser based on-
contact measurement probes. The dispense volume of the imprint material can be varied
depending upon the measurement data to yield a more uniform layer upon replication. In this
example, portion 2504a of the substrate has the greatest level of variability, portion 2504b has a
medium level of variability, and portion 2504c has the lowest level of variability. Therefore,
high volume imprint material may be deposited in portion 2504a, medium volume imprint
material is deposited into portion 2504b, and low/standard volume imprint material is deposited
into portion 2504c. As shown by the resulting product 2506, this results in a more uniform total
substrate/imprint material/imprint pattern thickness, which may in turn tune or benefit
performance of the imprinted device.
It is noted that while the example shows the variability due to non-uniformity in
thickness, other types of non-uniformity may also be addressed by this embodiment of the
invention. In another embodiment that variability may be due to existence of pits, peaks or other
anomalies or features associated with local positions on the substrate.
In the foregoing specification, the invention has been described with reference to
specific embodiments thereof. It will, however, be evident that various modifications and
changes may be made thereto without departing from the broader spirit and scope of the
invention. For example, the above-described process flows are described with reference to a
particular ordering of process actions. However, the ordering of many of the described process
actions may be changed without affecting the scope or operation of the invention. The
specification and drawings are, accordingly, to be regarded in an illustrative rather than
restrictive sense.
Various example embodiments of the invention are described herein. Reference is
made to these examples in a non-limiting sense. They are provided to illustrate more broadly
applicable aspects of the invention. Various changes may be made to the invention described
and equivalents may be substituted without departing from the true spirit and scope of the
invention. In addition, many modifications may be made to adapt a particular situation, material,
composition of matter, process, process act(s) or step(s) to the objective(s), spirit or scope of the
present invention. Further, as will be appreciated by those with skill in the art that each of the
individual variations described and illustrated herein has discrete components and features which
may be readily separated from or combined with the features of any of the other several
embodiments without departing from the scope or spirit of the present inventions. All such
modifications are intended to be within the scope of claims associated with this disclosure.
The invention includes methods that may be performed using the subject devices.
The methods may comprise the act of providing such a suitable device. Such provision may be
performed by the end user. In other words, the "providing" act merely requires the end user
obtain, access, approach, position, set-up, activate, power-up or otherwise act to provide the
requisite device in the subject method. Methods recited herein may be carried out in any order
of the recited events which is logically possible, as well as in the recited order of events.
Example aspects of the invention, together with details regarding material selection
and manufacture have been set forth above. As for other details of the present invention, these
may be appreciated in connection with the above-referenced patents and publications as well as
generally known or appreciated by those with skill in the art. The same may hold true with
respect to method-based aspects of the invention in terms of additional acts as commonly or
logically employed.
In addition, though the invention has been described in reference to several examples
optionally incorporating various features, the invention is not to be limited to that which is
described or indicated as contemplated with respect to each variation of the invention. Various
changes may be made to the invention described and equivalents (whether recited herein or not
included for the sake of some brevity) may be substituted without departing from the true spirit
and scope of the invention. In addition, where a range of values is provided, it is understood that
every intervening value, between the upper and lower limit of that range and any other stated or
intervening value in that stated range, is encompassed within the invention.
Also, it is contemplated that any optional feature of the inventive variations described
may be set forth and claimed independently, or in combination with any one or more of the
features described herein. Reference to a singular item, includes the possibility that there are
plural of the same items present. More specifically, as used herein and in claims associated
hereto, the singular forms "a," "an," "said," and "the" include plural referents unless the
specifically stated otherwise. In other words, use of the articles allow for "at least one" of the
subject item in the description above as well as claims associated with this disclosure. It is further
noted that such claims may be drafted to exclude any optional element. As such, this statement
is intended to serve as antecedent basis for use of such exclusive terminology as "solely," "only"
and the like in connection with the recitation of claim elements, or use of a "negative" limitation.
Without the use of such exclusive terminology, the term "comprising" in claims
associated with this disclosure shall allow for the inclusion of any additional element--
irrespective of whether a given number of elements are enumerated in such claims, or the
addition of a feature could be regarded as transforming the nature of an element set forth in such
claims. Except as specifically defined herein, all technical and scientific terms used herein are to
be given as broad a commonly understood meaning as possible while maintaining claim validity.
The breadth of the present invention is not to be limited to the examples provided
and/or the subject specification, but rather only by the scope of claim language associated with
this disclosure.
The above description of illustrated embodiments 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 devices that implement virtual or AR or hybrid systems and/or which employ
user interfaces, not necessarily the example AR systems generally described above.
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), 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.
When logic is implemented as software and stored in memory, logic or information
can be stored on any computer-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 computer-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 computer-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.
In the context of this specification, a “computer-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 computer-
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 nontransitory media.
Many of the methods described herein can be performed with variations. For
example, many of the methods may include additional acts, omit some acts, and/or perform acts
in a different order than as illustrated or described.
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, all of the U.S. patents, U.S. patent application publications, U.S. patent
applications, foreign patents, foreign patent applications and non-patent publications referred to
in this specification and/or listed in the Application Data Sheet. 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.
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.
Moreover, the various embodiments described above can be combined to provide
further embodiments. Aspects of the embodiments can be modified, if necessary to employ
concepts of the various patents, applications and publications to provide yet further
embodiments.
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.
Throughout this specification and the claims which follow, unless the context
requires otherwise, the word "comprise", and variations such as "comprises" or "comprising",
will be understood to imply the inclusion of a stated integer or step or group of integers or steps
but not the exclusion of any other integer or step or group of integers or steps.
The reference in this specification to any prior publication (or information derived
from it), or to any matter which is known, is not, and should not be taken as, an acknowledgement
or admission or any form of suggestion that that prior publication (or information derived from
it) or known matter forms part of the common general knowledge in the field of endeavour to
which this specification relates.
Claims (19)
1. A method for manufacturing an eyepiece comprising a first diffractive optical element, comprising: depositing a first layer onto a first substrate, wherein the first layer comprises a first portion and a second portion, the first portion is deposited to have a first depth onto a first region on the first substrate, the first portion has a first optical index, the second portion is deposited to have a second depth onto a second region on the first substrate, and the second portion has a second optical index different from the first optical index; identifying a template having an imprint pattern formed thereon, the template comprising a first set of depth structures and a second set of depth structures, the first set of depth structures corresponding to the first depth of the first portion, and the second set of depth structures corresponding to the second depth of the second portion; and imprinting the imprint pattern into the first and the second portions on the first substrate with the template, wherein the imprint pattern comprises a diffraction pattern for the first diffractive optical element, the first portion is deposited to have the first depth according to at least a first optical function, the second portion is deposited to have the second depth according to at least a second optical function, before imprinting, and the first depth is different from the second depth.
2. The method of claim 1, wherein: imprinting, using at least the template, the first and second portions that are respectively deposited onto the first and second regions simultaneously to form a first pattern and a second pattern onto the first substrate, wherein the imprint pattern comprises the first pattern and the second pattern; and the template imprints the first pattern with the first set of depth structures onto the first portion of the materials, and the template imprints the second pattern with the second set of depth structures onto the second portion of the materials.
3. The method of claim 2, wherein the first pattern corresponds to a first diffraction grating pattern and the second pattern corresponds to a second diffraction grating pattern.
4. The method of claim 2 or 3, wherein the first function or the second function includes a first function of in-coupling gratings, a second function of orthogonal pupil expander gratings, or a third function of exit pupil expander gratings.
5. The method of any of the preceding claims, further comprising: depositing, for the first diffractive optical element of the eyepiece, a second layer above the first layer, wherein the second layer comprises a first material having a first refractive index value in a first region of the second layer, the second layer further comprises a second material having a second refractive index value in a second region of the second layer, the first substrate comprises a third material having a third refractive index value, and the first, second, and third refractive index values are selected based at least in part upon a first requirement for a diffraction efficiency or a second requirement for a field of view provided by the first diffractive optical element of the eyepiece.
6. The method of any of the preceding claims, further comprising: stacking, for the eyepiece, a second diffractive optical element above a first negative lens that is further stacked above the first diffractive optical element, wherein the first diffractive optical element is closer to a viewer's eye than the second diffractive optical element and defines a first focal plane with a first focal distance of optical infinity, the second diffractive element comprises a second substrate and defines a second focal plane with a second focal distance that is smaller than the first focal distance of the optical infinity, and the second diffractive element is separated from the first diffractive element by the first lens.
7. The method of claim 6, further comprising: stacking, for the eyepiece, a third diffractive optical element above the second diffractive optical element, wherein the third diffractive optical element comprises a third substrate and is disposed farther away from the viewer's eye than the second diffractive optical element, the third diffractive optical element defines a third focal plane with a third focal distance that is smaller than the second focal distance, and the third diffractive optical element is separated from the second diffractive element by a second lens.
8. The method of claim 7, further comprising: disposing, for the eyepiece, a compensation lens layer above the third diffractive optical element, wherein the compensation lens layer is selected based at least in part upon an aggregate power of the first and the second lens
9. The method of any of claim 7 or 8, wherein: the first lens and the second lens create wavefront divergence to define a different focal plane with a different focal distance that is smaller than the third focal distance.
10. The method of any of claims 7 to 9, further comprising stacking, for the eyepiece, one or more additional diffractive optical elements above the third diffractive optical element and away from the viewer's eye, wherein the third diffractive element is separated from the one or more additional diffractive optical elements by a separate lens, and the one or more diffractive optical elements respectively define respective focal planes with one or more corresponding focal distances that are smaller than the third focal distance.
11. The method of claim 10, further comprising: disposing a compensation lens layer above the one or more additional diffractive optical elements, wherein the compensation lens layer is selected based at least in part upon an aggregate power of lenses separating diffractive optical layers in the eyepiece.
12. The method of any of claims 7 to 11, wherein at least two of the first diffractive optical element, the second diffractive optical element, and the third diffractive optical element are multiplexed to create at least one additional focal plane in addition to the first focal plane, the second focal plane, and the third focal plane.
13. The method of any of claims 6 to 12, wherein at least some of the first portion of the materials is deposited above at least some of the second portion of the materials before imprinting the imprint pattern into the first and the second portions.
14. The method of any of claims 6 to 13, wherein the first diffractive optical element corresponds to a first set of one or more projectors, and the second diffractive optical element corresponds to a second set of one or more projectors.
15. The method of any of the preceding claims, further comprising: imprinting a first pattern of the imprint pattern into the first portion; and imprinting a second pattern into the second portion that is different from the first pattern, wherein the imprint pattern comprises the first pattern and the second pattern.
16. The method of any of the preceding claims, wherein a first substrate having a first imprinted pattern is overlaid onto a second substrate having a second imprint pattern.
17. The method of any of the preceding claims, further comprising: depositing, for the first diffractive optical element of the eyepiece, a second layer onto the first substrate, wherein the second layer is deposited on an opposite surface opposing a surface onto which the first layer is deposited, the second layer comprises a first material having a refractive index value in a first region of the second layer, the first substrate comprises a different material having a different refractive index value, the first and the third refractive index values are selected based at least in part upon a first requirement for a diffraction efficiency or a second requirement for a field of view provided by the first diffractive optical element of the eyepiece.
18. The method of any of the preceding claims, wherein the first refractive index value is smaller than the second refractive index value and a substrate refractive index value of the first substrate, and the substrate refractive index value is smaller than the second refractive index value.
19. The method of any of the preceding claims, further comprising determining a thickness value for the first layer based at least in part upon a light incident angle for the first layer, the first refractive index value, and the second refractive value.
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US201562128925P | 2015-03-05 | 2015-03-05 | |
US62/128,925 | 2015-03-05 | ||
US15/007,117 US9915826B2 (en) | 2013-11-27 | 2016-01-26 | Virtual and augmented reality systems and methods having improved diffractive grating structures |
US15/007,117 | 2016-01-26 | ||
PCT/US2016/021093 WO2016141372A1 (en) | 2015-03-05 | 2016-03-05 | Improved manufacturing for virtual and augmented reality systems and components |
Publications (2)
Publication Number | Publication Date |
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NZ735537A NZ735537A (en) | 2021-09-24 |
NZ735537B2 true NZ735537B2 (en) | 2022-01-06 |
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