Laser illumination device
An Electrically Switchable Bragg Grating (ESBG) despeckler device comprising at least one ESBG element recorded in a hPDLC sandwiched between transparent substrates to which transparent conductive coatings have been applied. At least one of said coatings is patterned to provide a two-dimensional array of independently switchable ESBG pixels. Each ESBG pixel has a first unique speckle state under said first applied voltage and a second unique speckle state under said second applied voltage.
1. An optical device comprising:
a source of image modulated light;
a plurality of grating elements sandwiched between transparent substrates, wherein the plurality of grating elements comprise;
an input grating disposed adjacent to one of said substrates for diverting input light from said source into a total internal reflection path within said transparent substrates; and
an output grating for directing light out of said total internal reflection path through one of said transparent substrates into a predefined set of output light paths,
wherein at least one of the grating elements comprises a plurality of grating pixels disposed in a layer,
wherein each said grating pixel is characterized by one of a predefined set of grating vectors, and
wherein each said grating pixel is configured to diffract light into one of a predefined set of diffracted light paths.
2. The optical device of claim 1 , wherein said output optical paths are angularly separated.
3. The optical device of claim 1 , wherein said output optical paths are substantially normal to said transparent substrates.
4. The optical device of claim 1 , wherein each of said grating pixels contains a planar grating.
5. The optical device of claim 1 , wherein said input light is collimated.
6. The optical device of claim 1 , wherein said plurality of grating pixels comprises a two dimensional array.
7. The optical device of claim 1 , wherein at least one of said grating pixels is switchable between a diffracting state and a non-diffracting state and wherein the at least one of said grating elements is recorded in a Holographic Polymer Dispersed Liquid Crystal.
8. The optical device of claim 1 , wherein at least one of said grating pixels is switchable between a diffracting state when a first voltage is applied and a non-diffracting state when a second voltage is applied and wherein said first voltage and second voltage are points on a time varying voltage characteristic.
9. The optical device of claim 1 , wherein each of said grating pixels has optical power.
10. The optical device of claim 1 , wherein each of said grating pixels converts incident light into diffuse light.
11. The optical device of claim 1 , wherein said at least one of the grating elements comprises overlapping first and second grating elements and grating pixels from said first and second grating elements at least partially overlap.
12. The optical device of claim 1 , wherein at least one of said grating pixels is switchable between a diffracting state when a first voltage is applied and a non-diffracting state when a second voltage is applied and wherein each of said grating pixels has phase retarding characteristics characterised in that the amount of retardation is proportional to the applied voltage.
13. The optical device of claim 1 , wherein at least one of said grating pixels is switchable between a diffracting state when a first voltage is applied and a non-diffracting state when a second voltage is applied and wherein each of said grating pixels has light diffusing characteristics characterised in that the amount of diffusion is proportional to the applied voltage.
14. The optical device of claim 1 wherein each of said grating pixels encodes the optical characteristics of an axicon.
15. The optical device of claim 1 wherein each of said grating pixels encodes the optical characteristics of a sub wavelength grating phase retarder.
16. The optical illumination device of claim 1 , wherein each said ESBG pixel encodes the optical characteristics of a diffuser.
17. The optical device of claim 1 , wherein said source of image modulated light comprises a flat panel microdisplay.
18. The optical device of claim 1 , wherein light in said output light paths is collimated.
19. The optical device of claim 1 , wherein said plurality of grating pixels comprises a one-dimensional array.