Light guide device, optical display system and display device
Disclosed are a light guide device, an optical display system, and a display device. The light guide device includes a substrate and a first diffraction structure provided at the substrate. The first diffraction structure includes a first grating. The first grating includes a plurality of first grating units provided at intervals of a first period P 1 along a first vector direction u 1 and at intervals of a second period P 2 along a second vector direction u 2 . The first vector direction u 1 is intersected with the second vector direction u 2 , the first period P 1 is longer than the second period P 2 , forming unequal periods in two vector directions, and the first period P 1 is at least 1.5 times the second period P 2.
1 . A light guide device, comprising a substrate and a first diffraction structure provided at the substrate, wherein:
the first diffraction structure comprises a first grating;
the first grating comprises a plurality of first grating units provided at intervals of a first period P 1 along a first vector direction u 1 and at intervals of a second period P 2 along a second vector direction u 2 ;
the first vector direction u 1 is intersected with the second vector direction u 2 , the first period P 1 is longer than the second period P 2 , forming unequal periods in two vector directions, and the first period P 1 is at least 1.5 times the second period P 2 ;
the light guide device further comprises a second diffraction structure provided at the substrate;
the second diffraction structure is configured for coupling incident light into the substrate;
the substrate is configured for totally reflecting the incident light from the second diffraction structure to the first diffraction structure;
the first diffraction structure is configured for coupling out light and is composed of the first grating, and the first grating is an improved one-dimensional grating with a period of P and a vector direction of u;
the first grating satisfies:
2
π
P
IC
u
IC
+
2
π
P
u
+
2
π
P
2
u
2
=
0
;
and
P IC is a grating period of the second diffraction structure, u IC is a vector direction of the second diffraction structure, and P IC and u IC constitute grating vector information of the second diffraction structure.
2 . An optical display system, comprising:
the light guide device according to claim 1 ; and
an optical machine configured for projecting light onto the light guide device.
3 . A display device, comprising:
a housing; and
the optical display system according to claim 2 , wherein the optical display system is provided in the housing.
4 . The light guide device according to claim 1 , wherein the first diffraction structure further comprises a second grating, and the second grating comprises a plurality of second grating units;
the plurality of second grating units are provided at intervals of a third period P 3 along a third vector direction u 3 and at intervals of a fourth period P 4 along a fourth vector direction u 4 , and the third vector direction u 3 is intersected with the fourth vector direction u 4 ,
the first grating is combined with the second grating in a set manner; and
the first vector direction u 1 is same as the third vector direction u 3 , the first period P 1 is same as the third period P 3 , and the second vector direction u 2 and the fourth vector direction u 4 are on a same line.
5 . The light guide device according to claim 4 , wherein the light guide device satisfies: |K 0 +ΔK IC +ΔK 4 ±ΔK 2 |>(2π/λ)*n 2 ;
K 0 is vector information of the incident light, K 0 =(2π/λ)u 0 , λ is a wavelength of the incident light, and u 0 is an incident direction;
ΔK IC is the grating vector information of the second diffraction structure;
ΔK 4 is fourth vector information of the second grating and comprises the fourth vector direction u 4 and the fourth period P 4 ;
ΔK 2 is second vector information of the first grating and comprises the second vector direction u 2 and the second period P 2 ; and
n 2 is a refractive index of the substrate.
6 . The light guide device according to claim 4 , wherein the light guide device satisfies: |K 0 +ΔK IC +ΔK 3 ±ΔK 2 |>(2π/λ)*n 2 ;
K 0 is vector information of the incident light, K 0 =(2π/λ) u 0 , λ is a wavelength of the incident light, u 0 is an incident direction;
ΔK IC is the grating vector information of the second diffraction structure;
ΔK 3 is third vector information of the second grating and comprises the third vector direction u 3 and the third period P 3 ;
ΔK 2 is second vector information of the first grating and comprises the second vector direction u 2 and the second period P 2 ; and
n 2 is a refractive index of the substrate.
7 . The light guide device according to claim 1 , wherein the first grating unit comprises one or more sub-gratings.
8 . The light guide device according to claim 1 , wherein the light guide device satisfies: |K 0 +ΔK IC ±ΔK 2 |>(2π/λ)*n 2 ;
K 0 is vector information of the incident light, K 0 =(2π/λ)u 0 , λ is a wavelength of the incident light, and u 0 is an incident direction;
ΔK IC is the grating vector information of the second diffraction structure;
ΔK 2 is second vector information of the first grating and comprises the second vector direction u 2 and the second period P 2 ; and
n 2 is a refractive index of the substrate.