U.S. patent application number 16/568897 was filed with the patent office on 2021-03-18 for low-obliquity beam scanner with polarization-selective grating.
The applicant listed for this patent is Facebook Technologies, LLC. Invention is credited to Babak Amirsolaimani, Weichuan Gao, Ying Geng, Brian Wheelwright.
Application Number | 20210080719 16/568897 |
Document ID | / |
Family ID | 1000005430101 |
Filed Date | 2021-03-18 |
United States Patent
Application |
20210080719 |
Kind Code |
A1 |
Amirsolaimani; Babak ; et
al. |
March 18, 2021 |
LOW-OBLIQUITY BEAM SCANNER WITH POLARIZATION-SELECTIVE GRATING
Abstract
A beam scanner of a projector-based near-eye display includes a
polarization volume hologram (PVH) grating. The PVH grating
receives a polarized light beam from a light source and couples the
beam to a tiltable reflector, e.g. a 2D tiltable MEMS reflector,
for angular scanning the beam. The light beam impinging onto the
tiltable reflector is separated from the light beam reflected from
the tiltable reflector by polarization, due to the PVH grating
diffracting light of only one handedness of polarization. Upon
reflection from the tiltable reflector, the beam changes the
handedness of polarization, which enables its separation from the
impinging beam. The beam scanner may receive multiple light beams
from multiple light sources. A projector and a near-eye display
based on such beam scanners are also disclosed.
Inventors: |
Amirsolaimani; Babak;
(Redmond, WA) ; Wheelwright; Brian; (Sammamish,
WA) ; Geng; Ying; (Bellevue, WA) ; Gao;
Weichuan; (Redmond, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Facebook Technologies, LLC |
Menlo Park |
CA |
US |
|
|
Family ID: |
1000005430101 |
Appl. No.: |
16/568897 |
Filed: |
September 12, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 5/1814 20130101;
G02B 2027/0174 20130101; G02B 2027/014 20130101; G02B 5/32
20130101; G02B 27/0172 20130101 |
International
Class: |
G02B 27/01 20060101
G02B027/01; G02B 5/18 20060101 G02B005/18; G02B 5/32 20060101
G02B005/32 |
Claims
1. A beam scanner comprising: a first redirecting diffraction
grating configured to diffract an impinging first light beam to
obtain a second light beam having a first handedness of
polarization; a polarization volume hologram (PVH) grating disposed
and configured to receive and diffract the second light beam by
reflective diffraction to obtain a third light beam, wherein a
chromatic dispersion of the first redirecting diffraction grating
is opposite to a chromatic dispersion of the PVH grating; and a
tiltable reflector disposed and configured to receive and reflect
the third light beam at a variable angle back towards the PVH
grating; wherein the third light beam reflected by the tiltable
reflector has a second handedness of polarization opposite to the
first handedness, whereby the third light beam propagates through
the PVH grating.
2. The beam scanner of claim 1, wherein the PVH grating comprises a
liquid crystal layer comprising liquid crystal molecules in a
periodic helical configuration.
3. The beam scanner of claim 2, wherein the liquid crystal
molecules have spatially varying azimuthal angle at a surface of
the liquid crystal layer.
4. The beam scanner of claim 2, wherein the periodic helical
configuration is polymer-stabilized.
5. The beam scanner of claim 2, wherein the liquid crystal
molecules comprise nematic liquid crystal molecules in a
cholesteric configuration including a plurality of helical periods
between top and bottom surfaces of the liquid crystal layer.
6. The beam scanner of claim 1, further comprising a collimator
upstream of the first redirecting diffraction grating, wherein the
collimator is configured to collimate the first light beam
impinging onto the first redirecting diffraction grating.
7. The beam scanner of claim 1, further comprising a second
redirecting diffraction grating configured to diffract an impinging
fourth light beam to obtain a fifth light beam having the first
handedness of polarization; wherein the PVH grating is disposed and
configured to receive and diffract the fifth light beam by
reflective diffraction to obtain a sixth light beam, wherein a
chromatic dispersion of the second redirecting diffraction grating
is opposite to the chromatic dispersion of the PVH grating; wherein
the tiltable reflector is configured to receive and reflect the
sixth light beam at a variable angle back towards the PVH grating;
and wherein the sixth light beam reflected by the tiltable
reflector has the second handedness of polarization opposite to the
first handedness, whereby the sixth light beam propagates through
the PVH grating.
8. The beam scanner of claim 7, wherein the first and second
redirecting diffraction gratings are disposed side-by-side.
9. The beam scanner of claim 1, wherein the tiltable reflector
comprises a 2D microelectromechanical system (MEMS) tiltable
reflector.
10. A projector comprising: a first light source for providing a
first light beam; a first redirecting diffraction grating disposed
and configured to receive and diffract the first light beam to
obtain a second light beam having a first handedness of
polarization; a polarization volume hologram (PVH) grating disposed
and configured to receive and diffract the second light beam by
reflective diffraction to obtain a third light beam, wherein a
chromatic dispersion of the first redirecting diffraction grating
is opposite to a chromatic dispersion of the PVH grating; and a
tiltable reflector disposed and configured to receive and reflect
the third light beam at a variable angle back towards the PVH
grating; wherein the third light beam reflected by the tiltable
reflector has a second handedness of polarization opposite to the
first handedness, whereby the third light beam propagates through
the PVH grating.
11. The projector of claim 10, wherein the PVH grating comprises a
liquid crystal layer comprising liquid crystal molecules in a
periodic helical configuration.
12. The projector of claim 11, wherein the liquid crystal molecules
have spatially varying azimuthal angle at a surface of the liquid
crystal layer.
13. The projector of claim 11, further comprising a collimator in
an optical path between the first light source and the first
redirecting diffraction grating, wherein the collimator is
configured to collimate the first light beam impinging onto the
first redirecting diffraction grating.
14. The projector of claim 13, wherein the first light source
comprises a plurality of individually controllable emitters
optically coupled to the collimator for providing a plurality of
collimated sub-beams, wherein the first light beam impinging onto
the first redirecting diffraction grating comprises the plurality
of collimated sub-beams.
15. The projector of claim 14, wherein the plurality of
individually controllable emitters comprises an emitter of a red
color channel, an emitter of a green color channel, and an emitter
of a blue color channel of an image to be displayed by the
projector.
16. The projector of claim 10, further comprising: a second light
source for providing a fourth light beam; and a second redirecting
diffraction grating configured to diffract an impinging fourth
light beam to obtain a fifth light beam having the first handedness
of polarization; wherein the PVH grating is disposed and configured
to receive and diffract the fifth light beam by reflective
diffraction to obtain a sixth light beam, wherein a chromatic
dispersion of the second redirecting diffraction grating is
opposite to the chromatic dispersion of the PVH grating; wherein
the tiltable reflector is configured to receive and reflect the
sixth light beam at a variable angle back towards the PVH grating;
and wherein the sixth light beam reflected by the tiltable
reflector has the second handedness of polarization opposite to the
first handedness, whereby the sixth light beam propagates through
the PVH grating.
17. A near-eye display comprising: a first light source for
providing a first light beam; a first redirecting diffraction
grating disposed and configured to receive and diffract the first
light beam to obtain a second light beam having a first handedness
of polarization; a polarization volume hologram (PVH) grating
disposed and configured to receive and diffract the second light
beam by reflective diffraction to obtain a third light beam,
wherein a chromatic dispersion of the first redirecting diffraction
grating is opposite to a chromatic dispersion of the PVH grating; a
tiltable reflector disposed and configured to receive and reflect
the third light beam at a variable angle back towards the PVH
grating, wherein the third light beam reflected by the tiltable
reflector has a second handedness of polarization opposite to the
first handedness, whereby the third light beam propagates through
the PVH grating; and a controller operably coupled to the first
light source and the tiltable reflector and configured to: operate
the tiltable reflector to cause the third light beam reflected from
the tiltable reflector and propagated through the PVH grating to
have a beam angle corresponding to a first pixel of an image to be
displayed; and operate the first light source in coordination with
operating the tiltable reflector, such that the third light beam
has brightness corresponding to the first pixel.
18. The near-eye display of claim 17, further comprising a
pupil-replicating waveguide disposed proximate the PVH grating and
configured to receive and propagate therein the third light beam
propagated through the PVH grating.
19. The near-eye display of claim 17, further comprising a
collimator in an optical path between the first light source and
the first redirecting diffraction grating, wherein the collimator
is configured to collimate the first light beam impinging onto the
first redirecting diffraction grating; wherein the first light
source comprises a plurality of emitters optically coupled to the
collimator for providing a plurality of collimated sub-beams each
corresponding to a color channel of the image to be displayed,
wherein the first light beam impinging onto the first redirecting
diffraction grating comprises the plurality of collimated
sub-beams; and wherein the controller is operably coupled to the
plurality of emitters and is configured to operate the plurality of
emitters in coordination with operating the tiltable reflector,
such that the third light beam has color corresponding to the first
pixel.
20. The near-eye display of claim 17, further comprising: a second
light source for providing a fourth light beam; and a second
redirecting diffraction grating configured to diffract an impinging
fourth light beam to obtain a fifth light beam having the first
handedness of polarization; wherein the PVH grating is disposed and
configured to receive and diffract the fifth light beam by
reflective diffraction to obtain a sixth light beam, wherein a
chromatic dispersion of the second redirecting diffraction grating
is opposite to the chromatic dispersion of the PVH grating; wherein
the tiltable reflector is configured to receive and reflect the
sixth light beam at a variable angle back towards the PVH grating;
wherein the sixth light beam reflected by the tiltable reflector
has the second handedness of polarization opposite to the first
handedness, whereby the sixth light beam propagates through the PVH
grating; and wherein the controller is operably coupled to the
second light source and configured to: operate the tiltable
reflector to cause the sixth light beam reflected from the tiltable
reflector and propagated through the PVH grating to have a beam
angle corresponding to a second pixel of the image to be displayed;
and operate the second light source in coordination with operating
the tiltable reflector, such that the sixth light beam has
brightness corresponding to the second pixel.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to wearable headsets, and in
particular to components and modules for wearable visual display
headsets.
BACKGROUND
[0002] Head mounted displays (HMD), helmet mounted displays,
near-eye displays (NED), and the like are being used increasingly
for displaying virtual reality (VR) content, augmented reality (AR)
content, mixed reality (MR) content, etc. Such displays are finding
applications in diverse fields including entertainment, education,
training and biomedical science, to name just a few examples. The
displayed VR/AR/MR content can be three-dimensional (3D) to enhance
the experience and to match virtual objects to real objects
observed by the user. Eye position and gaze direction, and/or
orientation of the user may be tracked in real time, and the
displayed imagery may be dynamically adjusted depending on the
user's head orientation and gaze direction, to provide a better
experience of immersion into a simulated or augmented
environment.
[0003] Compact display devices are desired for head-mounted
displays. Because a display of HMD/NED is usually worn on the head
of a user, a large, bulky, unbalanced, and/or heavy display device
would be cumbersome and may be uncomfortable for the user to
wear.
[0004] Projector-based displays provide images in angular domain,
which can be observed by a user directly, without an intermediate
screen or a large display panel. A waveguide may be used to carry
the image in angular domain to the user's eye. The lack of a screen
or high numerical aperture collimating optics in a scanning
projector display enables size and weight reduction of the display.
A scanner for a projector display needs to be compact, fast, have a
wide scanning range, and preserve the optical quality of the beam
being scanned to form an image in angular domain.
SUMMARY
[0005] In accordance with the present disclosure, there is provided
a beam scanner comprising a first redirecting diffraction grating
configured to diffract an impinging first light beam to obtain a
second light beam having a first handedness of polarization. A
polarization volume hologram (PVH) grating is disposed and
configured to receive and diffract the second light beam by
reflective diffraction to obtain a third light beam. A chromatic
dispersion of the first redirecting diffraction grating is opposite
to a chromatic dispersion of the PVH grating. A tiltable reflector
is disposed and configured to receive and reflect the third light
beam at a variable angle back towards the PVH grating. The third
light beam reflected by the tiltable reflector has a second
handedness of polarization opposite to the first handedness,
whereby the third light beam propagates through the PVH
grating.
[0006] In some embodiments, the PVH grating comprises a liquid
crystal layer comprising liquid crystal molecules in a periodic
helical configuration. The liquid crystal molecules may have
spatially varying azimuthal angle at a surface of the liquid
crystal layer. The periodic helical configuration may be
polymer-stabilized. The liquid crystal molecules may be nematic
liquid crystal molecules in a cholesteric configuration including a
plurality of helical periods between top and bottom surfaces of the
liquid crystal layer.
[0007] In some embodiments, the beam scanner further includes a
collimator upstream of the first redirecting diffraction grating.
The collimator is configured to collimate the first light beam
impinging onto the first redirecting diffraction grating. The beam
scanner may further include a second redirecting diffraction
grating configured to diffract an impinging fourth light beam to
obtain a fifth light beam having the first handedness of
polarization. The PVH grating may be disposed and configured to
receive and diffract the fifth light beam by reflective diffraction
to obtain a sixth light beam, where a chromatic dispersion of the
second redirecting diffraction grating is opposite to the chromatic
dispersion of the PVH grating. The tiltable reflector may be
configured to receive and reflect the sixth light beam at a
variable angle back towards the PVH grating. The sixth light beam
reflected by the tiltable reflector has the second handedness of
polarization opposite to the first handedness, whereby the sixth
light beam propagates through the PVH grating. The first and second
redirecting diffraction gratings may be disposed side-by-side. The
tiltable reflector may include a 2D microelectromechanical system
(MEMS) tiltable reflector, for example.
[0008] In accordance with the present disclosure, there is provided
a projector comprising a first light source for providing a first
light beam. A first redirecting diffraction grating is disposed and
configured to receive and diffract the first light beam to obtain a
second light beam having a first handedness of polarization. A PVH
grating is disposed and configured to receive and diffract the
second light beam by reflective diffraction to obtain a third light
beam. A chromatic dispersion of the first redirecting diffraction
grating is opposite to a chromatic dispersion of the PVH grating. A
tiltable reflector is disposed and configured to receive and
reflect the third light beam at a variable angle back towards the
PVH grating. The third light beam reflected by the tiltable
reflector has a second handedness of polarization opposite to the
first handedness, whereby the third light beam propagates through
the PVH grating.
[0009] In some embodiments, the PVH grating comprises a liquid
crystal layer comprising liquid crystal molecules in a periodic
helical configuration. The liquid crystal molecules may have
spatially varying azimuthal angle at a surface of the liquid
crystal layer.
[0010] In some embodiments, the projector further includes a
collimator in an optical path between the first light source and
the first redirecting diffraction grating. The collimator is
configured to collimate the first light beam impinging onto the
first redirecting diffraction grating. The first light source may
include a plurality of individually controllable emitters optically
coupled to the collimator for providing a plurality of collimated
sub-beams. The first light beam impinging onto the first
redirecting diffraction grating comprises the plurality of
collimated sub-beams. The plurality of individually controllable
emitters may include an emitter of a red color channel, an emitter
of a green color channel, and an emitter of a blue color channel of
an image to be displayed by the projector.
[0011] In some embodiments, the projector further includes a second
light source for providing a fourth light beam and a second
redirecting diffraction grating configured to diffract an impinging
fourth light beam to obtain a fifth light beam having the first
handedness of polarization. The PVH grating may be disposed and
configured to receive and diffract the fifth light beam by
reflective diffraction to obtain a sixth light beam, wherein a
chromatic dispersion of the second redirecting diffraction grating
is opposite to the chromatic dispersion of the PVH grating. The
tiltable reflector may be configured to receive and reflect the
sixth light beam at a variable angle back towards the PVH grating.
The sixth light beam reflected by the tiltable reflector has the
second handedness of polarization opposite to the first handedness,
whereby the sixth light beam propagates through the PVH
grating.
[0012] In accordance with the present disclosure, there is further
provided a near-eye display comprising a first light source for
providing a first light beam, a first redirecting diffraction
grating disposed and configured to receive and diffract the first
light beam to obtain a second light beam having a first handedness
of polarization, and a PVH grating disposed and configured to
receive and diffract the second light beam by reflective
diffraction to obtain a third light beam. A chromatic dispersion of
the first redirecting diffraction grating is opposite to a
chromatic dispersion of the PVH grating. The near-eye display
further includes a tiltable reflector disposed and configured to
receive and reflect the third light beam at a variable angle back
towards the PVH grating. The third light beam reflected by the
tiltable reflector has a second handedness of polarization opposite
to the first handedness, whereby the third light beam propagates
through the PVH grating. A controller isoperably coupled to the
first light source and the tiltable reflector. The controller is
configured to operate the tiltable reflector to cause the third
light beam reflected from the tiltable reflector and propagated
through the PVH grating to have a beam angle corresponding to a
first pixel of an image to be displayed. The controller is further
configured to operate the first light source in coordination with
operating the tiltable reflector, such that the third light beam
has brightness corresponding to the first pixel. In some
embodiments, the near-eye display further includes a
pupil-replicating waveguide disposed proximate the PVH grating and
configured to receive and propagate therein the third light beam
propagated through the PVH grating.
[0013] In some embodiments, the near-eye display further includes a
collimator in an optical path between the first light source and
the first redirecting diffraction grating. The collimator is
configured to collimate the first light beam impinging onto the
first redirecting diffraction grating. The first light source may
include a plurality of emitters optically coupled to the collimator
for providing a plurality of collimated sub-beams each
corresponding to a color channel of the image to be displayed. The
first light beam impinging onto the first redirecting diffraction
grating comprises the plurality of collimated sub-beams. The
controller is operably coupled to the plurality of emitters and is
configured to operate the plurality of emitters in coordination
with operating the tiltable reflector, such that the third light
beam has luminance and/or color corresponding to the first
pixel.
[0014] The near-eye display may further include a second light
source for providing a fourth light beam, and a second redirecting
diffraction grating configured to diffract an impinging fourth
light beam to obtain a fifth light beam having the first handedness
of polarization. The PVH grating may be disposed and configured to
receive and diffract the fifth light beam by reflective diffraction
to obtain a sixth light beam, wherein a chromatic dispersion of the
second redirecting diffraction grating is opposite to the chromatic
dispersion of the PVH grating. The tiltable reflector may be
configured to receive and reflect the sixth light beam at a
variable angle back towards the PVH grating. The sixth light beam
reflected by the tiltable reflector has the second handedness of
polarization opposite to the first handedness, whereby the sixth
light beam propagates through the PVH grating. The controller may
be operably coupled to the second light source and configured to
operate the tiltable reflector to cause the sixth light beam
reflected from the tiltable reflector and propagated through the
PVH grating to have a beam angle corresponding to a second pixel of
the image to be displayed. The controller may be further configured
to operate the second light source in coordination with operating
the tiltable reflector, such that the sixth light beam has
brightness and/or color corresponding to the second pixel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Exemplary embodiments will now be described in conjunction
with the drawings, in which:
[0016] FIG. 1A is a schematic cross-sectional view of a
polarization volume hologram (PVH) grating of this disclosure;
[0017] FIG. 1B is a schematic diagram illustrating the principle of
operation of the PVH grating of FIG. 1A;
[0018] FIG. 2 is a side cross-sectional view of a near-eye display
(NED) of this disclosure including a low-obliquity beam scanner
equipped with the PVH grating of FIGS. 1A and 1B;
[0019] FIGS. 3A, 3B, and 3C are frontal views of multi-emitter
light sources usable with the NED of FIG. 2;
[0020] FIG. 4 is a side cross-sectional view of an NED of this
disclosure including multiple light sources and a low-obliquity
beam scanner coupling multiple light beams to a same tiltable
reflector;
[0021] FIG. 5A is a graph of aspect ratio of a field of view (FOV)
of a scanning projector display as a function of beam
obliquity;
[0022] FIG. 5B is a schematic view of a FOV at zero obliquity in
FIG. 5A;
[0023] FIG. 5C is a schematic view of a FOV at maximum obliquity in
FIG. 5A;
[0024] FIG. 6 is a plan cross-sectional view of an NED including
beam scanners/projectors of this disclosure;
[0025] FIG. 7A is an isometric view of a head-mounted display
(headset) of this disclosure; and
[0026] FIG. 7B is a block diagram of a virtual reality system
including the headset of FIG. 7A.
DETAILED DESCRIPTION
[0027] While the present teachings are described in conjunction
with various embodiments and examples, it is not intended that the
present teachings be limited to such embodiments. On the contrary,
the present teachings encompass various alternatives and
equivalents, as will be appreciated by those of skill in the art.
All statements herein reciting principles, aspects, and embodiments
of this disclosure, as well as specific examples thereof, are
intended to encompass both structural and functional equivalents
thereof. Additionally, it is intended that such equivalents include
both currently known equivalents as well as equivalents developed
in the future, i.e., any elements developed that perform the same
function, regardless of structure.
[0028] As used herein, the terms "first", "second", and so forth
are not intended to imply sequential ordering, but rather are
intended to distinguish one element from another, unless explicitly
stated. Similarly, sequential ordering of method steps does not
imply a sequential order of their execution, unless explicitly
stated.
[0029] A tiltable reflector may be used to scan a light beam
emitted by a light source to form an image in angular domain for
direct observation by a user. As the light beam is scanned, the
brightness and/or color of the scanned light beam may be varied in
coordination with the scanning, in accordance with pixels of the
displayed image being pointed at by the scanner. The entire image
is formed by a display when the light beam is scanned in two
dimensions, e.g. over X- and Y-viewing angles, over the entire
frame or field of view (FOV) of the display. When the frame rate is
high enough, the eye integrates the scanned light beam, enabling
the user to see the displayed imagery substantially without
flicker.
[0030] One problem associated with near-eye display image scanners
is reduction of field of view (FOV) caused by an oblique angle of
incidence of the light beam onto a tiltable reflector of the
scanner. The oblique angle may be required by the optical geometry
used, e.g. to physically separate an impinging light beam from the
scanned, i.e. reflected, light beam. The FOV reduction is caused by
distortion of the solid angle representing the range of scanning at
oblique angles of incidence of light beam at the tiltable
reflector.
[0031] In accordance with the present disclosure, the output
(scanned) light beam may be spatially separated from the input
optical beam by polarization. This obviates the need in geometrical
separation of the beams by oblique angles of incidence, resulting
in a compact configuration providing a nearly straight angle of
incidence at the tiltable reflector when the latter is in a center
(non-tilted) angular position. Low obliquity of the impinging light
beam enables the scanning range to be utilized more
efficiently.
[0032] Grating structures based on so-called polarization volume
holograms may be used to separate the input and output light beams
by polarization. By way of example, referring to FIG. 1A, a
polarization volume hologram (PVH) grating 100 includes an LC layer
104 bound by opposed top 105 and bottom 106 parallel surfaces. The
LC layer 104 may include an LC fluid containing rod-like LC
molecules 107 with positive dielectric anisotropy, e.g. nematic LC
molecules. A chiral dopant may be added to the LC fluid, causing
the LC molecules in the LC fluid to self-organize into a periodic
helical configuration including helical structures 108 extending
between the top 105 and bottom 106 parallel surfaces of the LC
layer 104. Such a configuration of the LC molecules 107, termed
herein a cholesteric configuration, includes a plurality of helical
periods p, e.g. at least two, at least five, at least ten, at least
twenty, or at least fifty helical periods p between the top 105 and
bottom 106 parallel surfaces of the LC layer 104. Boundary LC
molecules 107b at the top surface 105 of the LC layer 104 may be
oriented at an angle to the top surface 105. The boundary LC
molecules 107b may have a spatially varying azimuthal angle, e.g.
linearly varying along X-axis parallel to the top surface 105, as
shown in FIG. 1A. To that end, an alignment layer 112 may be
provided at the top surface 105 of the LC layer 104. The alignment
layer 112 may be configured to provide the desired orientation
pattern of the boundary LC molecules 107b, such as the linear
dependence of the azimuthal angle on the X-coordinate. A pattern of
spatially varying polarization directions of the UV light may be
selected to match a desired orientation pattern of the boundary LC
molecules 107a at the top surface 105 and/or the bottom surface 106
of the LC layer 104. When the alignment layer 112 is coated with
the cholesteric LC fluid, the boundary LC molecules 107a are
oriented along the photopolymerized chains of the alignment layer
112, thus adopting the desired surface orientation pattern.
Adjacent LC molecules adopt helical patterns extending from the top
105 to the bottom 106 surfaces of the LC layer 104, as shown.
[0033] The boundary LC molecules 107b define relative phases of the
helical structures 108 having the helical period p. The helical
structures 108 form a volume grating comprising helical fringes 114
tilted at an angle .PHI., as shown in FIG. 1A. The steepness of the
tilt angle .PHI. depends on the rate of variation of the azimuthal
angle of the boundary LC molecules 107b at the top surface 105 and
p. Thus, the tilt angle .PHI. is determined by the surface
alignment pattern of the boundary LC molecules 107A at the
alignment layer 112. The volume grating has a period .LAMBDA..sub.x
along X-axis and .LAMBDA..sub.y along Y-axis. In some embodiments,
the periodic helical structures 108 of the LC molecules 107 may be
polymer-stabilized by mixing in a stabilizing polymer into the LC
fluid, and curing (polymerizing) the stabilizing polymer.
[0034] The helical nature of the fringes 114 of the volume grating
makes the PVH grating 100 preferably responsive to light of
polarization having one particular handedness, e.g. left- or
right-circular polarization, while being substantially
non-responsive to light of the opposite handedness of polarization.
Thus, the helical fringes 114 make the PVH grating 100
polarization-selective. This is illustrated in FIG. 1B, which shows
a light beam 120 impinging onto the PVH grating 100. The light beam
120 includes a left circular polarized (LCP) beam component 121 and
a right circular polarized (RCP) beam component 122. The LCP beam
component 121 propagates through the PVH grating 100 substantially
without diffraction. Herein, the term "substantially without
diffraction" means that, even though an insignificant portion of
the beam (the LCP beam component 121 in this case) might diffract,
the portion of the diffracted light energy is so small that it does
not impact the intended performance of the PVH grating 100. The RCP
beam component 122 of the light beam 120 undergoes diffraction,
producing a diffracted beam 122'. The polarization selectivity of
the PVH grating 100 results from the effective refractive index of
the grating being dependent on the relationship between the
handedness, or chirality, of the impinging light beam and the
handedness, or chirality, of the grating fringes 114. It is further
noted that the sensitivity of the PVH 100 to right circular
polarized light in particular is only meant as an illustrative
example. When handedness of the helical fringes 114 is reversed,
the PVH 100 may be made sensitive to left circular polarized
light.
[0035] Referring to FIG. 2, a near-eye display (NED) 200 includes a
projector 202 optically coupled to a pupil-replicating waveguide
204. The projector 202 includes a light source 206 for providing
image light 208 of controllable brightness and/or color(s), and a
beam scanner 210 for receiving scanning the image light 208 across
an input grating 212 of the pupil-replicating waveguide 204. An
optional collimator 214 may be disposed in an optical path between
the light source 208 and the beam scanner 210, for collimating the
image light 208 to obtain a first light beam 221. The light source
may provide polarized light of a pre-defined handedness, e.g. LCP
or RCP light. A polarizer, e.g. a circular polarizer, may be
provided for this purpose.
[0036] The beam scanner 210 includes a first redirecting
diffraction grating 216 configured to diffract the impinging first
light beam 221 to obtain a second light beam 222, which is right
circular polarized. The first redirecting diffraction grating 216
may, but does not have to be, a PVH grating. The PVH grating 100 is
disposed in a path of the second light beam 222 and configured to
receive and diffract the second light beam 222 by reflective
diffraction to obtain a third light beam 223. A chromatic
dispersion of the first redirecting diffraction 216 grating is
selected to be opposite to a chromatic dispersion of the PVH
grating 100, e.g. the chromatic dispersion may have the same
amplitude but opposite sign. Thus, the chromatic dispersions of the
first redirecting diffraction 216 and the PVH grating 100 at least
partially offset each other or even completely cancel each other,
and therefore, when the image light 208 includes light at multiple
wavelengths, the reflected third light beam 223 will not be
wavelength dispersed, i.e. the beam angle of the reflected third
light beam 223 will not be dependent on wavelength.
[0037] A tiltable reflector 218, e.g. a 2D microelectromechanical
system (MEMS) tiltable reflector, is disposed in an optical path of
the third light beam 223, e.g. under the PVH grating 100, and
configured to receive and reflect the third light beam 223 at a
variable angle back towards the PVH grating 100. The third light
beam 223 reflected by the tiltable reflector 218 changes the
handedness of polarization upon reflection. This happens because
the direction of propagation of the reflected third light beam 223
changes, while the phase relationship between x- and y-component of
the light field of the third light beam 223 impinging onto the
tiltable reflector 218 remains substantially the same. Since the
handedness of the circular polarization is determined with the
account of direction of propagation, the handedness of the
reflected third light beam 223 changes as well. The third light
beam 223 changes handedness of its polarization to an opposite
handedness and, as a result, propagates through the PVH grating 100
substantially without diffraction. The third light beam 223
impinges onto the input grating 212 of the pupil-replicating
waveguide 204 disposed over the PVH 100 at a location and angle
depending on angle of tilt of the tiltable reflector 218. For
example, when the tiltable reflector 218 is in a left position
218A, the third light beam 223 impinges into the input grating 212
at a first location and angle 220A; and when the tiltable reflector
218 is in a right position 218B, the third light beam 223 impinges
into the input grating 212 at a second location and angle 220B.
During scanning, the tiltable reflector 218 may oscillate between
the left position 218A and the right position 218B. Although the
tilting is shown only about one axis in FIG. 2, the tiltable
reflector 218 may tilt/scan about two axes, i.e. about X and Y
axes.
[0038] By coordinating the instantaneous brightness and/or color of
the image light 208 generated by the light source 206 with an
instantaneous angle of scanning provided by the beam scanner 210,
an image in angular domain may be formed. The scanned third light
beam 223 is in-coupled by the input grating 212 to propagate within
the pupil-replicating waveguide 204. The pupil-replicating
waveguide 204 out-couples multiple laterally offset copies of the
third light beam 223 while preserving the beam angle, thus
replicating the image in the angular domain over an output area of
the pupil-replicating waveguide 204 for direct observation by a
user's eye, not shown.
[0039] Referring to FIGS. 3A, 3B, and 3C, the light source 206 may
include a plurality of individually controllable emitters, such as
superluminescent light-emitting diodes (SLEDs), for example.
Several emitters may be provided for each color channel. In some
embodiments, four red emitters 300R may be provided for red (R)
color channel (dark-shaded circles); four green emitters 300G may
be provided for green (G) color channel (medium-shaded circles);
and four blue emitters 300B may be provided for blue (B) color
channel (light-shaded circles). The emitters 300R, 300G, and 300B
may each be ridge emitters sharing a common semiconductor
substrate. The emitters 300R, 300G, and 300B may be disposed in a
line pattern (FIG. 3A); in a zigzag pattern (FIG. 3B); or in a
honeycomb pattern (FIG. 3C), to name just a few examples.
[0040] Having a plurality of emitters illuminating a same tiltable
reflector enables one to scan light beams generated by these
emitters together as a group. When the light source 206 includes a
plurality of individual emitters, the first light beam 221
impinging onto the first redirecting diffraction grating 216
includes the plurality of sub-beams collimated together by the
collimator 214 and co-propagating at a slight angle w.r.t each
other. Maximum angular cone of the sub-beams may be less than 5
degrees, or less than 2 degrees, or less than 1 degree in some
embodiments. Multiple emitters and, in some cases, multiple light
sources may be used to provide redundancy in case some of light
sources fail, increase image resolution, increase overall image
brightness, etc. Multiple light sources may each be equipped with
its own collimator.
[0041] Referring to FIG. 4 with further reference to FIG. 2, an NED
400 of FIG. 4 is similar to the NED 200 of FIG. 2, and includes
similar elements. The NED 400 includes first 406 and second 408
light sources, e.g. those depicted in FIGS. 3A, 3B, and 3C,
producing the first light beam 221 and a fourth light beam 224,
respectively. A beam scanner 410 of the NED 400 of FIG. 4 further
includes a second redirecting diffraction grating 416 configured to
diffract an impinging fourth light beam 224 provided by the second
light source 408. The diffracted fourth light beam 224 forms a
fifth light beam 225, which has the same handedness of polarization
as the second light beam 222, i.e. RCP in this example.
[0042] The PVH grating 100 is disposed and configured to receive
and diffract the fifth light beam 225 by reflective diffraction, to
obtain a sixth light beam 226. The first 216 and second 416
redirecting diffraction gratings may be disposed side-by-side and
parallel to the PVH grating 100, as shown. A small gap, e.g. 0.5
mm-3 mm gap, may be provided to avoid image light propagating in
the pupil-replicating waveguide 204 from entering the PVH 100. This
results in a compact configuration, and leaves room for the two
light sources 406 and 408 to be disposed side-by-side. Similarly to
the case of the first redirecting diffraction grating 216, the
chromatic dispersion of the second redirecting diffraction grating
416 may be selected to be opposite to the chromatic dispersion of
the PVH grating 100, such that the sixth light beam 226 is
substantially not wavelength-dispersed, i.e. individual wavelengths
sub-beams of the sixth light beam 226 all propagate substantially
parallel to one another. The tiltable reflector 218 is configured
to receive and reflect the sixth light beam 226 at a variable angle
back towards the PVH grating 100. The sixth light beam 226
reflected by the tiltable reflector 218 has the second handedness
of polarization opposite to the first handedness, whereby the sixth
light beam 226 propagates through the PVH grating 100 and impinges
onto the input grating 212 of the pupil-replicating waveguide 204.
The angles of incidence of the third 223 and sixth 226 light beams
may be selected to be different. Such a configuration enables
different areas of a field of view (FOV) of the NED 400 to be
powered by different light sources. This enables one to broaden the
overall FOV of the NED 400 without expanding the scanning range of
the tiltable reflector 218. The FOV portions corresponding to
different light sources may overlap at a central area of the FOV,
which may provide means for increasing spatial resolution of the
NED 400 in the central FOV area. The PVH grating 100 may include a
plurality of PVH sub-gratings optimized for individual color
channels.
[0043] The NEDs 200 of FIG. 2 and 400 of FIG. 4 provide a
low-obliquity coupling of light beam(s) to a tiltable reflector.
Herein, the term "low obliquity" means a low angle of incidence,
i.e. a normal incidence, at the tiltable reflector when in a
nominal, e.g. a center or zero, angle of tilt. One advantage of
having low obliquity is illustrated in FIGS. 5A to 5C. Referring
first to FIG. 5A, an aspect ratio of a FOV of a projector using a
tiltable reflector is plotted as a function of obliquity, i.e.
angle of incidence at the tiltable reflector when in nominal or
center position. The aspect ration is plotted for four cases: 75
degrees by 50 degrees on-axis FOV; 60 degrees by 40 degrees on-axis
FOV; 45 degrees by 30 degrees on-axis FOV; and 30 degrees by 20
degrees on-axis FOV. The aspect ratio drops from 1.5 at zero
obliquity, i.e. normal incidence, to about 1.1 at 40 degrees
obliquity angle.
[0044] FIG. 5B shows a zero-obliquity scanning angular area 500B
and an associated inscribed rectangular zero-obliquity FOV 502B.
The zero-obliquity FOV 502B solid angle is covering most of the
zero-obliquity scanning angular area 500B. By comparison, FIG. 5C
shows a 40 degrees obliquity scanning angular area 500C and an
associated inscribed rectangular oblique FOV 502C. The oblique FOV
502C solid angle occupies a smaller percentage of the 40 degrees
obliquity scanning angular area 500C, and is almost 2 times less
than the zero-obliquity FOV 502B. Thus, the low-obliquity coupling
improves the utilization of the scanning range of a tiltable
reflector, enabling wider fields of view at the same scanning range
of the tiltable reflector.
[0045] Referring to FIG. 6, a near-eye display (NED) 600 includes a
frame 601 having a form factor of a pair of eyeglasses. The frame
601 may support, for each eye: a projector 602 for providing
display light carrying an image in angular domain, an electronic
driver 604 operably coupled to the projector 602 for powering the
projector 602, and a pupil replicator 632 optically coupled to the
projector 602.
[0046] Each projector 602 may include beam scanners and light
sources described herein, for example and without limitation the
beam scanner 210 of FIG. 2, or the beam scanner 410 of FIG. 4.
Light sources for these projectors may include a substrate
supporting an array of single-mode or multimode semiconductor light
sources. For example, the light sources 206 (FIG. 2) and 406 and
408 (FIG. 4) may include side-emitting laser diodes,
vertical-cavity surface-emitting laser diodes, SLEDs, or
light-emitting diodes, for providing a plurality of light beams as
described above with reference to FIGS. 3A, 3B, and 3C. Collimators
for the light sources may include concave mirrors, bulk lenses,
Fresnel lenses, holographic lenses, pancake lenses, etc. The pupil
replicators 632 may include waveguides equipped with a plurality of
surface relief and/or volume holographic gratings. The function of
the pupil replicators 632 is to provide multiple laterally offset
copies of the display light beams provided by the projectors 602 at
respective eyeboxes 612.
[0047] A controller 605 is operably coupled to the light sources
and tiltable reflectors of the projectors 602. The controller 605
may be configured to determine the X- and Y-tilt angles of the
tiltable reflectors of the projectors 602. The controller 605
determines which pixel or pixels of the image to be displayed
correspond to the determined X- and Y-tilt angles. Then, the
controller 605 determines the brightness and/or color of these
pixels, and operates the electronic drivers 604 accordingly for
providing powering electric pulses to the light sources of the
projectors 602 to produce light pulses at power level(s)
corresponding to the determined pixel brightness and color.
[0048] In some embodiments, the controller 605 may be configured to
operate, for each eye, the tiltable reflector 218 to cause the
light beam reflected from the tiltable reflector 218 and propagated
through the respective PVH grating 100 to have a beam angle
corresponding to a pixel of an image to be displayed. The
controller 605 may be further configured to operate the
corresponding light source in coordination with operating the
tiltable reflector 218, such that the light beam has brightness
and/or color(s) corresponding to the pixel being displayed. In
multi-light source embodiments, the controller 605 may be
configured to operate the corresponding light sources in
coordination, to provide a larger FOV, an improved scanning
resolution, increased brightness of the display, etc., as described
herein. For example, in embodiment where the projectors for both of
user's eyes each include two light sources, the controller 605 may
be configured to operate the tiltable reflector 218 to cause two
light beams reflected from the tiltable reflector and propagated
through the PVH grating to have beam angle corresponding to
respective two pixels of an image to be displayed, and operate the
light sources in coordination with operating the tiltable reflector
218, such that the two light beam have brightness and/or color
corresponding to the two respective pixels. More light sources than
two may be provided, each light source including one or a plurality
of emitters, for one or a plurality of color channels of the image
being displayed.
[0049] Embodiments of the present disclosure may include, or be
implemented in conjunction with, an artificial reality system. An
artificial reality system adjusts sensory information about outside
world obtained through the senses such as visual information,
audio, touch (somatosensation) information, acceleration, balance,
etc., in some manner before presentation to a user. By way of
non-limiting examples, artificial reality may include virtual
reality (VR), augmented reality (AR), mixed reality (MR), hybrid
reality, or some combination and/or derivatives thereof. Artificial
reality content may include entirely generated content or generated
content combined with captured (e.g., real-world) content. The
artificial reality content may include video, audio, somatic or
haptic feedback, or some combination thereof. Any of this content
may be presented in a single channel or in multiple channels, such
as in a stereo video that produces a three-dimensional effect to
the viewer. Furthermore, in some embodiments, artificial reality
may also be associated with applications, products, accessories,
services, or some combination thereof, that are used to, for
example, create content in artificial reality and/or are otherwise
used in (e.g., perform activities in) artificial reality. The
artificial reality system that provides the artificial reality
content may be implemented on various platforms, including a
wearable display such as an HMD connected to a host computer
system, a standalone HMD, a near-eye display having a form factor
of eyeglasses, a mobile device or computing system, or any other
hardware platform capable of providing artificial reality content
to one or more viewers.
[0050] Referring to FIG. 7A, an HMD 700 is an example of an AR/VR
wearable display system which encloses the user's face, for a
greater degree of immersion into the AR/VR environment. The HMD 700
is an embodiment of the NED 200 of FIG. 2 or the NED 400 of FIG. 4,
for example. The function of the HMD 700 is to augment views of a
physical, real-world environment with computer-generated imagery,
and/or to generate the entirely virtual 3D imagery. The HMD 700 may
include a front body 702 and a band 704. The front body 702 is
configured for placement in front of eyes of a user in a reliable
and comfortable manner, and the band 704 may be stretched to secure
the front body 702 on the user's head. A display system 780 may be
disposed in the front body 702 for presenting AR/VR imagery to the
user. Sides 706 of the front body 702 may be opaque or
transparent.
[0051] In some embodiments, the front body 702 includes locators
708 and an inertial measurement unit (IMU) 710 for tracking
acceleration of the HMD 700, and position sensors 712 for tracking
position of the HMD 700. The IMU 710 is an electronic device that
generates data indicating a position of the HMD 700 based on
measurement signals received from one or more of position sensors
712, which generate one or more measurement signals in response to
motion of the HMD 700. Examples of position sensors 712 include:
one or more accelerometers, one or more gyroscopes, one or more
magnetometers, another suitable type of sensor that detects motion,
a type of sensor used for error correction of the IMU 710, or some
combination thereof. The position sensors 712 may be located
external to the IMU 710, internal to the IMU 710, or some
combination thereof.
[0052] The locators 708 are traced by an external imaging device of
a virtual reality system, such that the virtual reality system can
track the location and orientation of the entire HMD 700.
Information generated by the IMU 710 and the position sensors 712
may be compared with the position and orientation obtained by
tracking the locators 708, for improved tracking accuracy of
position and orientation of the HMD 700. Accurate position and
orientation is important for presenting appropriate virtual scenery
to the user as the latter moves and turns in 3D space.
[0053] The HMD 700 may further include a depth camera assembly
(DCA) 711, which captures data describing depth information of a
local area surrounding some or all of the HMD 700. To that end, the
DCA 711 may include a laser radar (LIDAR), or a similar device. The
depth information may be compared with the information from the IMU
710, for better accuracy of determination of position and
orientation of the HMD 700 in 3D space.
[0054] The HMD 700 may further include an eye tracking system 714
for determining orientation and position of user's eyes in real
time. The obtained position and orientation of the eyes also allows
the HMD 700 to determine the gaze direction of the user and to
adjust the image generated by the display system 780 accordingly.
In one embodiment, the vergence, that is, the convergence angle of
the user's eyes gaze, is determined. The determined gaze direction
and vergence angle may also be used for real-time compensation of
visual artifacts dependent on the angle of view and eye position.
Furthermore, the determined vergence and gaze angles may be used
for interaction with the user, highlighting objects, bringing
objects to the foreground, creating additional objects or pointers,
etc. An audio system may also be provided including e.g. a set of
small speakers built into the front body 702.
[0055] Referring to FIG. 7B, an AR/VR system 750 includes the HMD
700 of FIG. 7A, an external console 790 storing various AR/VR
applications, setup and calibration procedures, 3D videos, etc.,
and an input/output (I/O) interface 715 for operating the console
790 and/or interacting with the AR/VR environment. The HMD 700 may
be "tethered" to the console 790 with a physical cable, or
connected to the console 790 via a wireless communication link such
as Bluetooth.RTM., Wi-Fi, etc. There may be multiple HMDs 700, each
having an associated I/O interface 715, with each HMD 700 and I/O
interface(s) 715 communicating with the console 790. In alternative
configurations, different and/or additional components may be
included in the AR/VR system 750. Additionally, functionality
described in conjunction with one or more of the components shown
in FIGS. 7A and 7B may be distributed among the components in a
different manner than described in conjunction with FIGS. 7A and 7B
in some embodiments. For example, some or all of the functionality
of the console 715 may be provided by the HMD 700, and vice versa.
The HMD 700 may be provided with a processing module capable of
achieving such functionality.
[0056] As described above with reference to FIG. 7A, the HMD 700
may include the eye tracking system 714 (FIG. 7B) for tracking eye
position and orientation, determining gaze angle and convergence
angle, etc., the IMU 710 for determining position and orientation
of the HMD 700 in 3D space, the DCA 711 for capturing the outside
environment, the position sensor 712 for independently determining
the position of the HMD 700, and the display system 780 for
displaying AR/VR content to the user. The display system 780
includes (FIG. 7B) an electronic display 725, for example and
without limitation, a liquid crystal display (LCD), an organic
light emitting display (OLED), an inorganic light emitting display
(ILED), an active-matrix organic light-emitting diode (AMOLED)
display, a transparent organic light emitting diode (TOLED)
display, a projector, or a combination thereof. The display system
780 further includes an optics block 730, whose function is to
convey the images generated by the electronic display 725 to the
user's eye. The optics block may include various lenses, e.g. a
refractive lens, a Fresnel lens, a diffractive lens, an active or
passive Pancharatnam-Berry phase (PBP) lens, a liquid lens, a
liquid crystal lens, etc., a pupil-replicating waveguide, grating
structures, coatings, etc. The display system 780 may further
include a varifocal module 735, which may be a part of the optics
block 730. The function of the varifocal module 735 is to adjust
the focus of the optics block 730 e.g. to compensate for
vergence-accommodation conflict, to correct for vision defects of a
particular user, to offset aberrations of the optics block 730,
etc.
[0057] The I/O interface 715 is a device that allows a user to send
action requests and receive responses from the console 790. An
action request is a request to perform a particular action. For
example, an action request may be an instruction to start or end
capture of image or video data or an instruction to perform a
particular action within an application. The I/O interface 715 may
include one or more input devices, such as a keyboard, a mouse, a
game controller, or any other suitable device for receiving action
requests and communicating the action requests to the console 790.
An action request received by the I/O interface 715 is communicated
to the console 790, which performs an action corresponding to the
action request. In some embodiments, the I/O interface 715 includes
an IMU that captures calibration data indicating an estimated
position of the I/O interface 715 relative to an initial position
of the I/O interface 715. In some embodiments, the I/O interface
715 may provide haptic feedback to the user in accordance with
instructions received from the console 790. For example, haptic
feedback can be provided when an action request is received, or the
console 790 communicates instructions to the I/O interface 715
causing the I/O interface 715 to generate haptic feedback when the
console 790 performs an action.
[0058] The console 790 may provide content to the HMD 700 for
processing in accordance with information received from one or more
of: the IMU 710, the DCA 711, the eye tracking system 714, and the
I/O interface 715. In the example shown in FIG. 7B, the console 790
includes an application store 755, a tracking module 760, and a
processing module 765. Some embodiments of the console 790 may have
different modules or components than those described in conjunction
with FIG. 7B. Similarly, the functions further described below may
be distributed among components of the console 790 in a different
manner than described in conjunction with FIGS. 7A and 7B.
[0059] The application store 755 may store one or more applications
for execution by the console 790. An application is a group of
instructions that, when executed by a processor, generates content
for presentation to the user. Content generated by an application
may be in response to inputs received from the user via movement of
the HMD 700 or the I/O interface 715. Examples of applications
include: gaming applications, presentation and conferencing
applications, video playback applications, or other suitable
applications.
[0060] The tracking module 760 may calibrate the AR/VR system 750
using one or more calibration parameters and may adjust one or more
calibration parameters to reduce error in determination of the
position of the HMD 700 or the I/O interface 715. Calibration
performed by the tracking module 760 also accounts for information
received from the IMU 710 in the HMD 700 and/or an IMU included in
the I/O interface 715, if any. Additionally, if tracking of the HMD
700 is lost, the tracking module 760 may re-calibrate some or all
of the AR/VR system 750.
[0061] The tracking module 760 may track movements of the HMD 700
or of the I/O interface 715, the IMU 710, or some combination
thereof. For example, the tracking module 760 may determine a
position of a reference point of the HMD 700 in a mapping of a
local area based on information from the HMD 700. The tracking
module 760 may also determine positions of the reference point of
the HMD 700 or a reference point of the I/O interface 715 using
data indicating a position of the HMD 700 from the IMU 710 or using
data indicating a position of the I/O interface 715 from an IMU
included in the I/O interface 715, respectively. Furthermore, in
some embodiments, the tracking module 760 may use portions of data
indicating a position or the HMD 700 from the IMU 710 as well as
representations of the local area from the DCA 711 to predict a
future location of the HMD 700. The tracking module 760 provides
the estimated or predicted future position of the HMD 700 or the
I/O interface 715 to the processing module 765.
[0062] The processing module 765 may generate a 3D mapping of the
area surrounding some or all of the HMD 700 ("local area") based on
information received from the HMD 700. In some embodiments, the
processing module 765 determines depth information for the 3D
mapping of the local area based on information received from the
DCA 711 that is relevant for techniques used in computing depth. In
various embodiments, the processing module 765 may use the depth
information to update a model of the local area and generate
content based in part on the updated model.
[0063] The processing module 765 executes applications within the
AR/VR system 750 and receives position information, acceleration
information, velocity information, predicted future positions, or
some combination thereof, of the HMD 700 from the tracking module
760. Based on the received information, the processing module 765
determines content to provide to the HMD 700 for presentation to
the user. For example, if the received information indicates that
the user has looked to the left, the processing module 765
generates content for the HMD 700 that mirrors the user's movement
in a virtual environment or in an environment augmenting the local
area with additional content. Additionally, the processing module
765 performs an action within an application executing on the
console 790 in response to an action request received from the I/O
interface 715 and provides feedback to the user that the action was
performed. The provided feedback may be visual or audible feedback
via the HMD 700 or haptic feedback via the I/O interface 715.
[0064] In some embodiments, based on the eye tracking information
(e.g., orientation of the user's eyes) received from the eye
tracking system 714, the processing module 765 determines
resolution of the content provided to the HMD 700 for presentation
to the user on the electronic display 725. The processing module
765 may provide the content to the HMD 700 having a maximum pixel
resolution on the electronic display 725 in a foveal region of the
user's gaze. The processing module 765 may provide a lower pixel
resolution in other regions of the electronic display 725, thus
lessening power consumption of the AR/VR system 750 and saving
computing resources of the console 790 without compromising a
visual experience of the user. In some embodiments, the processing
module 765 can further use the eye tracking information to adjust
where objects are displayed on the electronic display 725 to
prevent vergence-accommodation conflict and/or to offset optical
distortions and aberrations.
[0065] The hardware used to implement the various illustrative
logics, logical blocks, modules, and circuits described in
connection with the aspects disclosed herein may be implemented or
performed with a general purpose processor, a digital signal
processor (DSP), an application specific integrated circuit (ASIC),
a field programmable gate array (FPGA) or other programmable logic
device, discrete gate or transistor logic, discrete hardware
components, or any combination thereof designed to perform the
functions described herein. A general-purpose processor may be a
microprocessor, but, in the alternative, the processor may be any
conventional processor, controller, microcontroller, or state
machine. A processor may also be implemented as a combination of
computing devices, e.g., a combination of a DSP and a
microprocessor, a plurality of microprocessors, one or more
microprocessors in conjunction with a DSP core, or any other such
configuration. Alternatively, some steps or methods may be
performed by circuitry that is specific to a given function.
[0066] The present disclosure is not to be limited in scope by the
specific embodiments described herein. Indeed, other various
embodiments and modifications, in addition to those described
herein, will be apparent to those of ordinary skill in the art from
the foregoing description and accompanying drawings. Thus, such
other embodiments and modifications are intended to fall within the
scope of the present disclosure. Further, although the present
disclosure has been described herein in the context of a particular
implementation in a particular environment for a particular
purpose, those of ordinary skill in the art will recognize that its
usefulness is not limited thereto and that the present disclosure
may be beneficially implemented in any number of environments for
any number of purposes. Accordingly, the claims set forth below
should be construed in view of the full breadth and spirit of the
present disclosure as described herein.
* * * * *