Laser projector with reduced speckle

Patent metadata

Field	Value
Publication number	US-9482877-B2
Application number	US-201114110807-A
Country	US
Kind code	B2
Filing date	Apr 12, 2011
Priority date	Apr 12, 2011
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

The present invention provides a light source for a projector system, and method of operating the light source as well as a projector system that provides:
i. a substantially uniform brightness across the surface of an image modulator, and
ii. at each point of the surface of the image modulator a more uniform filling of the available angular space.
Embodiments of the present invention use a laser light source for use with an image modulator, the light source emitting light with multiple wavelengths for at least one primary color and a light integrator system that for each of the wavelengths is adapted to provide:
i. a substantially uniform brightness across the surface of the image modulator, and
ii. at each point of the surface of the image modulator a more uniform filling of the available angular space.

First claim

The invention claimed is:

1. A light source apparatus for use with a projector having a light modulator for receiving a plurality of light beams and for projecting the light beams towards a display, comprising:
a laser light source with multiple wavelengths for at least one primary color arranged to output a laser light beam;
an integrator assembly comprising:
a first integrator and a second integrator; and
a first light diffusing element, positioned in between said first integrator and said second integrator, wherein the first light diffusing element is arranged to receive a laser light and forward a plurality of light beams at a range of angles,

the integrator assembly being adapted such that for each of the wavelengths:
a substantially uniform brightness is achieved across the surface of an image modulator and
at each point of the surface of the image modulator a substantially uniform filling of the available angular space is achieved.

2. The light source of claim 1 , wherein the integrator assembly is adapted to provide a substantially uniform brightness across the surface of the image modulator and at each point of the surface of the image modulator a substantially uniform filling of the available angular space at each point in time.

3. The light source of claim 1 , wherein the first light diffusing element is a diffuser, a lenslet array, a diffraction element, a refractive prism array or a holographic element.

4. The light source of claim 1 , wherein any of the first integrator and the second integrator are a rod or a light pipe integrator.

5. The light source of claim 1 , wherein any of the first integrator and the second integrator are a fly-eye integrator.

6. A light source apparatus according to claim 1 , wherein the rod or light pipe integrator has a variable cross-section along its longitudinal axis.

7. A light source apparatus according to claim 4 , wherein the rod or light pipe integrator has a tapered cross-section along its longitudinal axis in at least one dimension.

8. A light source apparatus according to claim 1 , further comprising a second light diffusing element positioned in front of the first integrator.

9. A light source apparatus according to claim 1 , wherein the first light diffusing element is movable.

10. A light source apparatus according to claim 1 , wherein the first light diffusing element is static.

11. A light source apparatus according to claim 1 , wherein the first integrator has a different form and/or different length to width ratio compared to the second integrator.

12. A light source apparatus according to claim 11 , wherein the first integrator or the second integrator as a length to width ratio of greater than 7.5.

13. A light source apparatus according to claim 1 , wherein the first integrator is tapered and the second integrator is non-tapered or vice versa.

14. A light source apparatus according to claim 1 , wherein the laser light source comprises an array of light emitting devices, and wherein one of the devices outputs a light beam at one of the plurality of wavelengths.

15. A light source apparatus according to claim 14 , wherein multiple devices outputting a light beam at the same wavelength are offset from one another in the array, and are optionally evenly distributed across the array.

16. A light source apparatus according to claim 1 , wherein the plurality of wavelengths have an offset of less than 2 nm and optionally more than 0.5 nm from one another.

17. A light source apparatus according to claim 1 , wherein a light beam has two orthogonal polarizations.

18. A light source apparatus according to claim 17 , wherein the first or second diffuser element does not maintain polarization.

19. A light source apparatus according to claim 17 , wherein a time varying retarder is placed after the first and/or second diffuser element.

20. A light source apparatus according to claim 1 , wherein the multiple wavelengths are generated by multiple laser emitters.

21. A light source apparatus according to claim 1 , wherein the multiple wavelengths are generated by multiple laser packages.

22. A light source apparatus according to claim 20 , in which the number of individual laser emitters contributing to each wavelength is sufficiently high and the first and second diffusing element are static.

23. A projector comprising a light source apparatus-according to claim 1 .

24. A projector according to claim 23 , wherein said light source apparatus is provided with two orthogonal polarizations for at least one primary color and using a light integrator system that is conceived such that for each of the polarization directions:
v. a substantially uniform brightness is achieved across the surface of the image modulator, and
vi. at each point of the surface of the image modulator a substantially uniform filling of the available angular space is achieved.

Assignees

• Janssens Peter
• Barco Nv

Inventors

• Janssens Peter

Classifications

• G02B27/48 Primary

  Laser speckle optics · CPC title

• G02B27/0927

  Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat · CPC title

• G02B27/0994

  Fibers, light pipes (optical fibers per se G02B6/02) · CPC title

• G03B21/208

  Homogenising, shaping of the illumination light · CPC title

• G02B27/0955

  Lenses (lenses per se G02B3/00) · CPC title