Polarization-based processing of unpolarized image light
A display system includes a source of unpolarized image light, and a stack of polarization-selective optical elements operable to switchably convert the unpolarized image light into two orthogonally polarized light beams, each of which being switchable in at least one beam characteristic. An output polarizer selects one of the two orthogonally polarized light beams for providing to a user. A depolarizer may be disposed between an electronic display emitting polarized light and the stack. The depolarizer may be in the form of an LC bilayer with randomized in-plane optic axis.
1. A method comprising:
propagating unpolarized image light through a sequence of polarization-selective optical elements of a display system to obtain two orthogonally polarized light beams, each of which being switchable in at least one beam characteristic, the at least one beam characteristic comprising at least one of:
a beam convergence characteristic; or
a beam deflection angle; and
using an optical polarizer disposed downstream of the sequence of polarization-selective optical elements to select one of the two orthogonally polarized light beams as an output light beam for forming an image; and
propagating polarized image light through a depolarizer to obtain the unpolarized image light for providing to the sequence of polarization-selective optical elements, the depolarizer comprising a liquid crystal (LC) bilayer with a randomized in-plane optic axis.
2. The method of claim 1 , wherein the propagating of the unpolarized image light comprises propagating the unpolarized image light through a sequence of Pancharatnam-Berry phase (PBP) lenses of differing nominal optical powers.
3. The method of claim 1 , wherein the propagating of the unpolarized image light comprises propagating the unpolarized image light through a sequence of polarization gratings.
4. The method of claim 1 , further comprising switching a polarization state of the orthogonally polarized light beams downstream of a polarization-selective optical element of the sequence of polarization-selective optical elements.
5. The method of claim 4 , wherein the switching is performed using a switchable half-wave plate (HWP).
6. The method of claim 1 , wherein the propagating of the unpolarized image light comprises propagating the unpolarized image light through a switchable Pancharatnam-Berry phase (PBP) lens, the method further comprising switching the switchable PBP lens to a state having substantially zero optical power.
7. The method of claim 1 , wherein the propagating of the unpolarized image light comprises propagating the unpolarized image light through a switchable PBP grating, the method further comprising switching the switchable PBP grating to a non-diffracting state.
8. The method of claim 1 , wherein the two orthogonally polarized light beams are orthogonally linearly polarized.
9. The method of claim 8 , wherein the optical polarizer comprises a linear polarizer.