Methods, devices, and systems for illuminating spatial light modulators

1. A display device comprising:

one or more light emitters configured to emit light having at least a first polarization state and a second polarization state;

a waveguide disposed with respect to said one or more light emitters to receive the light emitted from said one or more light emitters such that at least some of said light is guided in the waveguide by total internal reflection, said waveguide configured to: i) eject the light having the first polarization state out of said waveguide, and ii) not eject the light having the second polarization state;

a spatial light modulator disposed with respect to said waveguide to receive said light ejected from said waveguide and modulate said light; and

a light recycling system configured to:

receive the light having the second polarization state that is not initially ejected from the waveguide;

convert the light having the second polarization state to light having the first polarization state; and

redirect the converted light having the first polarization state such that the redirected light is guided in the waveguide by total internal reflection and ejected from the waveguide toward the spatial light modulator.

2. The display device of claim 1 , wherein the light recycling system further comprises a quarter wave retarder disposed with respect to the reflective element to allow the light that is not initially ejected to pass to the reflective element, wherein the reflective element is configured to reflect the light back to pass said quarter wave retarder a second time, such that light having the second polarization state is converted to light having the first polarization state and redirected back into the waveguide.

3. The display device of claim 1 , further comprising one or more turning elements disposed relative to said waveguide to turn light guided within said waveguide out of said waveguide and to said spatial light modulator.

4. The display device of claim 3 , wherein said one or more turning elements comprise one or more microstructures or nanostructures configured to eject light having the first polarization state out of said waveguide.

5. The display device of claim 4 , further comprising a wire grid disposed between said waveguide and said one or more microstructures or nanostructures, wherein said wire grid is configured to transmit light having the first polarization state to said one or more microstructures or nanostructures and reflect light having the second polarization state.

6. The display device of claim 4 , wherein said one or more microstructures or nanostructures comprise one or more diffractive optical elements, or holographic optical elements.

7. The display device of claim 1 , wherein said waveguide comprises an angled surface to reflect light having the first polarization state to said spatial light modulator and transmit light having the second polarization state.

8. The display device of claim 7 , wherein said light recycling system comprises a polarization converter element disposed with respect to said reflective element to receive light reflected by said reflective element and convert light having the second polarization state to light having the first polarization state.

9. The display device of claim 1 , wherein the reflective element comprises a reflective surface that is concave with respect to an interior of the waveguide.

10. The display device of claim 1 , wherein the reflective element comprises at least a portion of a parabolic mirror or a spherical mirror.

11. The display device of claim 1 , wherein the reflective element comprises a holographic optical element.

12. The display device of claim 1 , wherein the one or more light emitters is in optical communication with the waveguide via an optical fiber.

13. The display device of claim 1 , comprising a polarization selective element comprising cholesteric liquid crystal, said polarization selective element comprising multiple layers of liquid crystal, different liquid crystal layers configured to diffract different wavelengths such that different wavelengths of light are directed toward said first surface.

14. The display device of claim 1 , further comprising:

at least one color mixing element comprising a first dichroic beam combiner element and a second dichroic beam combiner element;

wherein said one or more light emitters comprise:

a first light emitter configured to emit light of a first color into the at least one color mixing element; and

a second light emitter configured to emit light of a second color into the at least one color mixing element,

wherein the at least one color mixing element is configured to combine the light of the first color and the light of the second color, and

wherein the at least one color mixing element comprises one or more prisms, cube prisms, rectangular prisms, micro-prisms, and/or beam combiner plates.

15. The display device of claim 1 , further comprising an elongate reflective structure comprising:

a first sidewall and a second sidewall opposite the first sidewall;

an input aperture configured to receive light from the at least one light emitter; and an exit aperture configured to emit light,

wherein the elongate reflective structure is configured such that light from the at least one light source coupled into the elongate reflective structure through the input aperture propagates towards the exit aperture by multiple reflections from the first sidewall and the second sidewall, and

wherein the input aperture is located on the first sidewall and the exit aperture is located on the second sidewall.