CPC G02B 5/3083 (2013.01) [G02B 5/3016 (2013.01); G02B 6/005 (2013.01); G02B 27/0172 (2013.01)] | 20 Claims |
1. An optical element, comprising:
a first birefringent medium layer with orientations of directors of first optically anisotropic molecules spatially varying with a first in-plane pitch and a first vertical pitch, the first vertical pitch being a distance along a thickness direction of the first birefringent medium layer over which the directors rotate by a predetermined angle; and
a second birefringent medium layer with orientations of directors of second optically anisotropic molecules spatially varying with a second in-plane pitch and a second vertical pitch, the second birefringent medium layer being optically coupled with the first birefringent medium layer, the second vertical pitch being a distance along a thickness direction of the second birefringent medium layer over which the directors rotate by the same predetermined angle,
wherein the first in-plane pitch is substantially the same as the second in-plane pitch, and the second vertical pitch is smaller than the first vertical pitch, and
wherein the first birefringent medium layer is configured to diffract an input light toward the second birefringent medium layer, and the second birefringent medium layer is configured to reduce a diffraction of the input light by the first birefringent medium layer.
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