Waveguide laser illuminator incorporating a despeckler
There is provided an illumination device having: a laser; a waveguide including at least first and second transparent lamina; a first grating device for coupling light from the laser into a TIR path in the waveguide; a second grating device for coupling light from the TIR path out of the waveguide; and a third grating device for applying a variation of at least one of beam deflection, phase retardation or polarization rotation across the wavefronts of the TIR light. The first second and third grating devices are each sandwiched by transparent lamina.
1. An illumination device comprising:
a laser;
a waveguide comprising at least first and second transparent lamina;
a first grating device for coupling light from said laser into a TIR path in said waveguide;
a second grating device for coupling light from said TIR path out of said waveguide and towards a reflective microdisplay, wherein said second grating device is configured to transmit light reflected from said reflective microdisplay; and
a third grating device for applying a variation of at least one of beam deflection or phase retardation across wavefronts of light in said TIR path,
wherein said first, second, and third grating devices are each sandwiched by said transparent lamina.
2. The illumination device of claim 1 wherein said third grating device is electrically switchable, wherein transparent electrodes are applied to portions of said transparent lamina sandwiching said gratings, said electrodes substantially overlapping said grating device.
3. The illumination device of claim 1 wherein said third grating devices is electrically switchable, wherein transparent interdigitated electrodes are applied to portions of a transparent lamina overlapping said third grating device.
4. The illumination device of claim 1 wherein an optical prescription of said third grating device varies along said waveguide.
5. The illumination device of claim 1 wherein said first and second grating devices are grating lamina.
6. The illumination device of claim 1 wherein said third grating device comprises more than one grating lamina adjacently disposed along said waveguide.
7. The illumination device of claim 1 wherein said third grating device comprises a two dimensional array of SBG elements, wherein electrodes are applied to overlapping portions of said transparent lamina, said transparent lamina sandwiching said SBG elements, at least one of said electrodes being pixelated into elements substantially overlapping said SBG elements.
8. The illumination device of claim 1 wherein said first and second grating devices are SBGs.
9. The illumination device of claim 1 wherein said third grating device is a SBG.
10. The illumination device of claim 1 further comprising a fourth grating device for applying variation of at least one of beam deflection or phase retardation across the wavefronts of said TIR light, wherein said third and fourth grating devices overlap, wherein said third and fourth grating devices have identical prescriptions and are configured in reciprocal sense.
11. The illumination device of claim 1 wherein said third grating device is disposed along the TIR path between said first and second grating devices.
12. The illumination device of claim 1 wherein said third grating device diffuses light into the direction of said TIR path.
13. An illumination device comprising:
a laser;
a waveguide comprising at least first and second transparent lamina;
a first grating device comprising an array of selectively switchable grating elements, each of said grating element encode a beam deflector for coupling light from said laser into a TIR path in said waveguide and a lens having a Fourier plane in proximity to an illumination plane of said illumination device; and
a second grating device for coupling light from said TIR path out of said waveguide and towards a reflective microdisplay, wherein said second grating device is configured to transmit light reflected from said reflective microdisplay;
wherein said first and second grating devices are each sandwiched by said transparent lamina.