Transmission improvement for flat lens based AR/VR glasses
An artificial-reality display uses an anisotropic material to circularly-polarize light exiting a waveguide so that the artificial-reality display is relatively transparent.
1. A system comprising:
an optical source;
a waveguide;
a coupling element, wherein the coupling element is configured to couple light from the optical source into the waveguide;
a decoupling element, wherein the decoupling element is configured to couple light out of the waveguide so that light decoupled out of the waveguide has a uniform polarization;
a waveplate, wherein the waveplate is configured to convert light with the uniform polarization into circularly-polarized light; and
a geometric-phase lens configured to focus circularly-polarized light, wherein the waveplate is between the decoupling element and the geometric-phase lens, and wherein the waveplate and the geometric-phase lens are bonded together as part of a lens stack.
2. The system of claim 1 , wherein the uniform polarization is elliptical polarization.
3. The system of claim 1 , wherein light is polarized before entering into the waveguide.
4. The system of claim 1 , wherein the geometric-phase lens is a Pancharatnam Berry Phase (PBP) liquid crystal lens.
5. The system of claim 1 , wherein the waveplate has an anisotropic material that has a birefringence that is uniform across the waveplate.
6. The system of claim 1 , wherein the system comprises a linear polarizer between the optical source and the coupling element.
7. The system of claim 1 , further comprising a frame, wherein:
the frame is part of glasses to be worn by a user; and
the waveguide, the waveplate, and the geometric-phase lens are secured in the frame.
8. The system of claim 1 , wherein:
the lens stack is a first lens stack;
the system further comprises a second lens stack;
the second lens stack comprises a geometric-phase lens; and
the waveguide is between the first lens stack and the second lens stack.
9. A system comprising:
an optical source;
a waveguide;
a coupling element, wherein the coupling element is configured to couple light from the optical source into the waveguide;
a decoupling element, wherein:
the decoupling element couples light out of the waveguide; and
light coupled out of the waveguide has a spatially-varying polarization;
a waveplate, wherein the waveplate has a spatially-varying fast axis configured to convert light with the spatially-varying polarization into circularly-polarized light; and
a geometric-phase lens configured to focus circularly-polarized light, wherein the waveplate is between the decoupling element and the geometric-phase lens.
10. The system of claim 9 , wherein:
the waveplate is divided into a plurality of zones;
the plurality of zones includes a first zone and a second zone; and
the waveplate comprises an optically anisotropic material having a fast axis with an orientation that varies, such that:
the orientation of the fast axis in the first zone is at a first angle;
the orientation of the fast axis in the second zone is at a second angle; and
the first angle is not equal to the second angle.
11. The system of claim 10 , wherein the plurality of zones creates a residual defocus of combined light that is below a threshold value.
12. The system of claim 10 , wherein a number of the plurality of zones is equal to or greater than 25 and equal to or less than 225.
13. The system of claim 9 , further comprising a linear polarizer between the optical source and the coupling element.
14. The system of claim 9 , further comprising a frame, wherein:
the frame is part of glasses to be worn by a user; and
the waveguide, the waveplate, and the geometric-phase lens are secured in the frame.
15. The system of claim 9 , wherein light exiting the waveguide has spatially-varying, elliptical polarization.
16. A system comprising:
an optical source;
a waveguide;
a coupling element, wherein the coupling element is configured to couple light from the optical source into the waveguide;
a decoupling element, wherein the decoupling element is configured to couple light out of the waveguide;
a geometric-phase lens configured to focus circularly-polarized light; and
a circular polarizer comprising:
a linear polarizer having a polarization bandwidth, wherein:
the polarization bandwidth is equal to or greater than 5 nm and equal to or less than 50 nm; and
the linear polarizer has a transmission axis; and
a waveplate, wherein a combination of the linear polarizer and the waveplate is configured to pass one handedness of circularly-polarized light and block a second handedness of circularly-polarized light.
17. The system of claim 16 , wherein:
the linear polarizer is a first linear polarizer;
the polarization bandwidth is a first polarization bandwidth;
the system further comprises a second linear polarizer;
the second linear polarizer has a second polarization bandwidth, wherein:
the second polarization bandwidth is equal to or greater than 5 nm and equal to or less than 50 nm; and
the second polarization bandwidth is different than the first polarization bandwidth.
18. The system of claim 17 , wherein the first linear polarizer is configured to polarize red light and the second linear polarizer is configured to polarize blue light.
19. The system of claim 17 , wherein:
the system further comprises a third linear polarizer; and
the first linear polarizer, the second linear polarizer, and the third linear polarizer are part of the circular polarizer.
20. The system of claim 16 , wherein the geometric-phase lens is between the decoupling element and the circular polarizer.