| CPC G02B 5/1842 (2013.01) [G02B 6/0023 (2013.01); G02B 6/005 (2013.01)] | 10 Claims |
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1. A diffraction light guide plate, comprising:
a first diffraction substrate; and
a second diffraction substrate provided on the first diffraction substrate, wherein the first diffraction substrate includes a first diffraction grating layer in direct contact with one surface of the first diffraction substrate and a second diffraction grating layer in direct contact with an opposite surface of the first diffraction substrate,
the second diffraction substrate includes a third diffraction grating layer in direct contact with one surface of the second diffraction substrate,
when first incident light is emitted to the first diffraction grating layer included on one surface of the first diffraction substrate for the diffraction light guide plate including the first diffraction substrate, the first diffraction grating layer separates first light having a wavelength of 550 nm or more and 700 nm or less from the first incident light,
when second incident light, in which the first light is separated from the first incident light, is emitted to the second diffraction grating layer while being reflected or totally reflected from the internal side of the first diffraction substrate, the second diffraction grating layer separates second light having a wavelength of 400 nm or more and 550 nm or less from the second incident light, and
when third incident light, in which the second light is separated from the second incident light, is emitted to the third diffraction grating layer, the third diffraction grating layer separates third light having a wavelength of 450 nm or more and 650 nm or less from the third incident light,
wherein each of the first diffraction grating layer, the second diffraction grating layer and the third diffraction grating layer includes a first area onto which light is incident, a second area in which the incident light expands and moves, and a third area from which the moved light is extracted,
wherein each of the first areas includes a first diffraction pattern, each of the second areas includes a second diffraction pattern, and each of the third areas includes a third diffraction pattern,
wherein the first diffraction pattern, the second diffraction pattern, and the third diffraction pattern of the first diffraction grating layer differ in at least one of the inclination direction, angle of inclination, depth, or width,
wherein the each of the third diffraction patterns includes an inclined pattern structure having an angle of inclination of 50° or more and less than 90° with respect to a surface of the diffraction substrate on which the each of the third diffraction patterns are formed, wherein a duty of the inclined pattern gradually increases from one end to the other end of each of the third diffraction patterns in the respective third area, and the duty of the inclined pattern is 0.1 or more and 1.0 or less,
wherein the first areas of each of the first, second and third diffraction grating layers are included at corresponding positions on each of the first, second and third diffraction grating layers, respectively,
wherein third areas of each of the first, second and third diffraction grating layers are included at corresponding positions on each of the first, second and third diffraction grating layers, respectively, and
wherein a depth of the inclined pattern structure gradually increases from one end of the respective third area to the other end of the respective third area.
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