| CPC G02B 27/0101 (2013.01) [G02B 6/0016 (2013.01); G02B 6/0038 (2013.01)] | 15 Claims |
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1. A light guide device, comprising:
a light coupling-in region, comprising a plurality of first gratings;
a light expansion region, comprising a plurality of sub light expansion regions, wherein each of the sub light expansion regions comprises a plurality of second gratings, the sub light expansion regions comprise a first set of sub light expansion regions and a second set of sub light expansion regions, and each of the second gratings in the first set of sub light expansion regions only comprises a first microstructure and a second microstructure, wherein widths of the first microstructure, the second microstructure and the second grating in the second set of sub light expansion regions are different from each other;
a light coupling-out region, comprising a plurality of third gratings; and
a substrate, wherein the light coupling-in region, the light expansion region and the light coupling-out region are formed on a surface of the substrate, the first microstructure and the second microstructure are vertical columns forming on the surface of the substrate,
wherein, when an image light enters the light guide device from the light coupling-in region through the first gratings, the image light is first transmitted to the light expansion region in the light guide device, then transmitted to the light coupling-out region through the second gratings, and then emitted from the light coupling-out region through the third gratings.
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