Laser illumination device

• US 8,565,560 B2
• Filed: 07/16/2012
• Issued: 10/22/2013
• Est. Priority Date: 11/13/2006
• Status: Active Grant

• Current Assignee: DigiLens Inc
• Original Assignee: SBG Labs Inc.
• Inventors: Popovich, Milan Momcilo, Waldern, Jonathan David, Storey, John James
• Primary Examiner(s): KIM, ELLEN E
• Application Number:
  US13/549,868
• Publication Number:
  US 20120281943A1
• Time in Patent Office: 463 Days
• Field of Search: 385/10, 385/37, 349/2, 349/201, 349/202, 359/3, 359/15, 359/86, 359/22, 359/24, 359/618, 359/634, 234/54
• US Class Current: 385/10
• CPC Class Codes: G02B 27/425 in illumination systems mask illumination systems in photolithographic systems G03F7/70158
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0035 provided on the surface of the light guide or in the bulk of it
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02F 1/0136 for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation G02F1/0353 takes precedence
• CPC Class Codes: G02F 1/13342 Holographic polymer dispersed liquid crystals
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/13731 based on a field-induced phase transition G02F1/13781 takes precedence
• CPC Class Codes: G02F 2203/62 Switchable arrangements whereby the element being usually not switchable
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03H 1/0248 Volume holograms
• CPC Class Codes: G03H 1/32 Systems for obtaining speckle elimination

Abstract

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.

Claims

1. An optical device comprising:

at least one ESBG element sandwiched between transparent substrates, said ESBG element comprising a multiplicity of ESBG pixels disposed in a layer;

transparent conductive coatings applied to each said substrate, at least one of said coatings being patterned into independently addressable elements overlapping said pixels;

an electrical control circuit operative to apply voltages across each said pixel; and

a light coupling element disposed adjacent to one of said substrates for diverting input light from an external light source into a total internal reflection path within said substrates,

wherein each said pixel is characterized by one of a predefined set of grating vectors,

wherein each said pixel has one non-diffracting state and at least one diffracting state,

wherein each said ESBG pixel when in its diffracting state diffracts light out of said total internal reflection path through one of said substrates into one of a predefined set of output light paths.

2. The apparatus of claim 1 wherein said output optical paths are angularly separated.

3. The apparatus of claim 1 wherein said output optical paths are substantially normal to said substrates.

4. The apparatus of claim 1 wherein said pixel contains a planar grating.

5. The apparatus of claim 1 wherein said input light is collimated.

6. The apparatus of claim 1 wherein said multiplicity of pixels comprises a two dimensional array.

7. The apparatus of claim 1 wherein said input light is modulated with image information.

8. The apparatus of claim 1 wherein each said ESBG element is recorded in a Holographic Polymer Dispersed Liquid Crystal.

9. The apparatus of claim 1 wherein said first and second voltages are points on a time varying voltage characteristic.

10. The apparatus of claim 1 wherein each said pixel has optical power.

11. The apparatus of claim 1 wherein each said pixel converts incident light into diffuse light.

12. The apparatus of claim 1 wherein said ESBG elements comprise overlapping first and second ESBG elements and pixels from said first and second ESBG elements at least partially overlap.

13. The apparatus of claim 1 wherein each said pixel has phase retarding characteristics characterised in that the amount of retardation is proportional to said voltage.

14. The apparatus of claim 1 wherein each said pixel has light diffusing characteristics characterised in that the amount of diffusion is proportional to said voltage.

15. The apparatus of claim 1 wherein each said pixel encodes the optical characteristics of an axicon.

16. The apparatus device of claim 1 wherein each said pixel encodes the optical characteristics of a sub wavelength grating phase retarder.

17. The apparatus of claim 1 wherein said light coupling element is a grating device.

18. The apparatus of claim 1 wherein more than one of the pixels in an ESBG element is in its diffracting state at any time.

19. The apparatus of claim 1 wherein the spatio-temporal addressing of pixels by said electrical control circuit addresses said pixels is characterized by a cyclic process.

20. The apparatus of claim 1 wherein the spatio-temporal addressing of pixels by said electrical control circuit addresses said pixels is characterized by a random process.