Waveguide display system with wide field of view
Embodiments include an optical system that may be included in a waveguide display. An example optical system includes a first waveguide having a first transmissive diffractive in-coupler (DG1) and a first diffractive out-coupler (DG6) and a second waveguide having a second transmissive diffractive in-coupler (DG2), a reflective diffractive in-coupler (DG3), a second diffractive out-coupler (DG4), and a third diffractive out-coupler (DG5). The second transmissive diffractive in-coupler (DG2) is arranged between the first transmissive diffractive in-coupler (DG1) and the reflective diffractive in-coupler (DG3) in an input region.
1. An optical system comprising:
a first waveguide, configured to receive, at an input region of the optical system, light from a light source;
a second waveguide, configured to receive a first portion of the light, transmitted to the second waveguide by the first waveguide;
an output region configured to receive a second portion of the light diffracted in the first waveguide and to receive the first portion of the light diffracted in the second waveguide;
the first waveguide having a first transmissive diffractive in-coupler (DG1) at the input region of the optical system, for diffracting, from the light, blue light of a first incidence angle range and for diffracting, from the light, incoming green light of a third incidence angle range to a first diffractive out-coupler (DG6) in the output region of the optical system, and to pass-through, to the second waveguide of the optical system, from the light, blue light of a second incidence angle range, green light of a fourth incidence angle range and red light; and
the second waveguide having a second transmissive diffractive in-coupler (DG2) for diffracting the blue light of the second incidence angle range received from the first waveguide, and the green light of the fourth incidence angle range received from the first waveguide, to a second diffractive out-coupler (DG4) in the output region, and a reflective diffractive in-coupler (DG3) for diffracting the red light received from the first waveguide to a third diffractive out-coupler (DG5) in the output region.
2. The optical system of claim 1 , wherein the light source comprises an image generator operative to provide an image at the input region, wherein the optical system is configured to substantially replicate the image at an output pupil region, the output pupil region including the first diffractive out-coupler (DG6), the second diffractive out-coupler (DG4), and the third diffractive out-coupler (DG5).
3. The optical system of claim 2 , wherein the optical system is configured to substantially replicate an image spanning a field of view of at least 100°.
4. The optical system of claim 2 , wherein the optical system is configured to replicate a full-color image.
5. The optical system of claim 1 , wherein the first transmissive diffractive in-coupler has a first grating pitch, the second transmissive diffractive in-coupler has a second grating pitch greater than the first grating pitch, and the reflective diffractive in-coupler has a third grating pitch greater than the second grating pitch.
6. The optical system of claim 1 , wherein
d
1
=
M
1
λ
n
2
sin
Φ
WG
1
G
+
sin
Θ
WG
1
G
where d 1 is a grating pitch of the first transmissive diffractive in-coupler, M 1 is a non-zero integer, n 2 is a refractive index of the first waveguide, λ is a wavelength between 450 nm and 700 nm, Φ WG1 G is an angle between 55 and 90 degrees, and Θ WG1 G is substantially equal to an angle that diffracts into a critical angle of the second waveguide, where the critical angle of the second waveguide is arcsin (1/n 3 ), where n 3 is a refractive index of the second waveguide.
7. The optical system of claim 6 , wherein
d
2
=
M
2
λ
n
3
sin
Φ
WG
2
G
+
sin
Θ
WG
2
G
where d 2 is a grating pitch of the second transmissive diffractive in-coupler, M 2 is a non-zero integer, Φ WG2 G is an angle between 55 and 90 degrees, and Θ WG2 G is an angle within ±5 degrees of normal incidence.
8. The optical system of claim 1 , wherein:
a first grating pitch (d 1 ) of the first transmissive diffractive in-coupler is between 420 nm and 520 nm;
a second grating pitch (d 2 ) of the second transmissive diffractive in-coupler is between 600 nm and 700 nm; and
a third grating pitch (d 3 ) of the reflective diffractive in-coupler is between 720 nm and 820 nm.
9. The optical system of claim 1 , wherein:
a first grating pitch (d 1 ) of the first transmissive diffractive in-coupler is between 460 nm and 480 nm;
a second grating pitch (d 2 ) of the second transmissive diffractive in-coupler is between 640 nm and 660 nm; and
a third grating pitch (d 3 ) of the reflective diffractive in-coupler is between 760 nm and 780 nm.
10. The optical system of claim 1 , wherein:
a second grating pitch (d 2 ) of the second transmissive diffractive in-coupler is between 30% and 50% greater than a first grating pitch (d 1 ) of the first transmissive diffractive in-coupler; and
a third grating pitch (d 3 ) of the reflective diffractive in-coupler is between 10% and 30% greater than the second grating pitch.
11. A method of operating an optical system, the method comprising:
directing light from a light source and input at an input region of the optical system, the light representing an image, onto a first transmissive diffractive in-coupler (DG1) of a first waveguide;
using the first transmissive diffractive in-coupler to couple into the first waveguide a first portion of the light corresponding to blue light, input at the input region at a first incidence angle range, and green light, input at the input region at a third incidence angle range, and using the first transmissive diffractive in-coupler to transfer, to a second waveguide, a second portion of the light, corresponding to blue light, input at the input region at a second incidence angle range, and green light, input at the input region at a fourth incidence angle range, and red light input at the input region;
using a second transmissive diffractive in-coupler (DG2) of a second waveguide to couple into the second waveguide a first part of the second portion of the light received from the first waveguide corresponding to the blue light received from the first waveguide, and the green light received from the first waveguide; and
using a reflective diffractive in-coupler (DG3) of the second waveguide to couple into the second waveguide a second part of the second portion of the light received from the first waveguide, corresponding to the red light received from the first waveguide.
12. The method of claim 11 , wherein
d
1
=
M
1
λ
n
2
sin
Φ
WG
1
G
+
sin
Θ
WG
1
G
where d 1 is a grating pitch the of first transmissive diffractive in-coupler, M 1 is a non-zero integer, n 2 is a refractive index of the first waveguide, λ is a wavelength between nd 700 nm, Φ WG1 G is an angle between 55 and 90 degrees, and Θ WG1 G is substantially equal to an angle that diffracts into a critical angle of the second waveguide, where the critical angle of the second waveguide is arcsin (1/n 3 ), where n 3 is a refractive index of the second waveguide.
13. The method of claim 12 , wherein
d
2
=
M
2
λ
n
3
sin
Φ
WG
2
G
+
sin
Θ
WG
2
G
where d 2 is a grating pitch of the second transmissive diffractive in-coupler (DG2), M 2 is a non-zero integer, Φ WG2 G is an angle between 55 and 90 degrees, and Θ WG2 G is an angle within ±5 degrees of normal incidence.