Low distortion imaging through a C-shape flat optical architecture

Patent metadata

Field	Value
Publication number	US-12449583-B2
Application number	US-202118020770-A
Country	US
Kind code	B2
Filing date	Aug 10, 2021
Priority date	Aug 13, 2020
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

Embodiments include an optical system that may be included in a waveguide display. A waveguide apparatus according to some embodiments includes an in-coupler grating having a first grating vector G 1 substantially perpendicular to a first axis, x; a first eye pupil expander grating having a second grating vector G 2 and a first angle Φ G with respect to the first axis; a second eye pupil expander grating having a third grating vector G 3 and an angle substantially equal to 90°+Φ G with respect to the first axis; and an out-coupler grating having a fourth grating vector G 4 substantially perpendicular to the first axis. Example embodiments describe relationships among the grating vectors, the angle Φ G , and associated parameters to achieve a satisfactory field of view while reducing distortion.

First claim

What is claimed:

1. A waveguide apparatus comprising:
an in-coupler grating configured to use diffraction order M 1 , the in-coupler grating having a first grating pitch Λ 1 and a first grating vector {right arrow over (G)} 1 substantially perpendicular to a first axis, {circumflex over (x)};
a first eye pupil expander grating configured to use diffraction order M 2 , the first eye pupil expander having a second grating pitch Λ 2 and second a grating vector {right arrow over (G)} 2 having a first angle Φ G with respect to the first axis;
a second eye pupil expander grating configured to use diffraction order M 3 , the second eye pupil expander having a third grating pitch Λ 3 and a third grating vector {right arrow over (G)} 3 having a second angle of between 80°+Φ G and 100°+Φ G with respect to the first axis; and
an out-coupler grating configured to use diffraction order M 4 , the out-coupler grating having a fourth grating pitch Λ 4 and a fourth grating vector {right arrow over (G)} 4 substantially perpendicular to the first axis;
wherein the out-coupler grating is configured to use a first diffractive order, and at least one of the in-coupler grating and the eye pupil expander gratings is configured to use a second diffractive order; and
wherein the third grating pitch Λ 3 of the second eye pupil expander substantially satisfies:

Λ
3

=

M
3

M
2

⁢

Λ
2

⁢

tan
⁡
(

Φ
G

)

.

2. The apparatus of claim 1 , wherein the second angle is between 85°+Φ G and 95°+Φ G with respect to the first axis.

3. The apparatus of claim 1 , wherein the second angle is substantially equal to 90°+Φ G with respect to the first axis.

4. The apparatus of claim 1 , wherein the out-coupler grating is configured to use a first diffractive order and the in-coupler grating and the first and second eye pupil expander gratings are configured to use a second diffractive order.

5. The apparatus of claim 1 , wherein the fourth grating pitch Λ 4 of the out-coupler substantially satisfies:

M
4

Λ
4

-

M
1

Λ
1

+

M
2

Λ
2

⁢

sin
⁡
(

Φ
G

)

=
0.

6. The apparatus of claim 1 , wherein the grating pitches Λ 2 and Λ 3 substantially satisfy:

Λ
2

=

Λ
3

=

M
⁢
λ
⁢

sin
⁡
(

Φ
G

-

φ
2

)

where

φ
=

sin

-
1

(

1
-

1

n
2

⁢
sin
⁢

θ
2
g

)

,

n 2 is a refractive index of the waveguide, and θ 2 g is a grazing angle.

7. The apparatus of claim 1 , wherein the grating pitch Λ 1 substantially satisfies:

Λ
1

=

M
1

⁢
λ

n
2

⁢
sin
⁢

θ
1
g

-

n
1

⁢
sin
⁢

θ
0
g

where λ is the wavelength of an incoming beam, n 1 is a refractive index of a medium in which the incoming beam is traveling, θ 1 g is a grazing angle, and θ 0 g is an angle of an incoming beam that diffracts to grazing angle θ 1 g .

8. The apparatus of claim 1 , wherein the grating pitches are within 20% of the following values:
Λ 1 =851.38 nm
Λ 2 =729.46 nm
Λ 3 =729.46 nm
Λ 4 =1308.64 nm.

9. The apparatus of claim 1 , wherein the grating pitches are within 10% of the following values:
Λ 1 =851.38 nm
Λ 2 =729.46 nm
Λ 3 =729.46 nm
Λ 4 =1308.64 nm.

10. The apparatus of claim 1 , wherein t

Assignees

• Interdigital Ce Patent Holdings Sas

Inventors

• Drazic Valter
• Shramkova Oksana

Classifications

• G02B2027/0132

  comprising binocular systems · CPC title

• G02B2027/0123

  comprising devices increasing the field of view · CPC title

• G02B27/0172 Primary

  characterised by optical features · CPC title

• G02B6/0076

  Stacked arrangements of multiple light guides of the same or different cross-sectional area · CPC title

• G02B6/0016

  Grooves, prisms, gratings, scattering particles or rough surfaces · CPC title