Speckle reduced laser projection with color gamut optimization

Patent metadata

Field	Value
Publication number	US-10712640-B2
Application number	US-201916423087-A
Country	US
Kind code	B2
Filing date	May 27, 2019
Priority date	May 28, 2018
Publication date	Jul 14, 2020
Grant date	Jul 14, 2020

Abstract

A method of image projection including selecting a set of desired chromaticity coordinates of a projection system, the projection system including a plurality of laser sources; determining a set of parameters of an expected operational environment; and configuring each laser source to have a power ratio and a power spectrum density function generating a normalized power spectrum density function of the projection system having the set of desired chromaticity coordinates and a wavelength diversity factor of at least 2 in the expected operational environment. A projection system including an input device configured to receive a set of desired chromaticity coordinates and a set of operational parameters; a plurality of laser sources each having a power ratio and a power spectrum density function configured to generate a normalized power spectrum density function producing the set of desired chromaticity coordinates and a wavelength diversity factor of at least 2.

First claim

The invention claimed is:

1. A method of image projection, comprising:
selecting a set of desired chromaticity coordinates of a projection system, the projection system including a plurality of laser sources;
determining a set of operational parameters of an expected operational environment, the set of operational parameters including a standard deviation of surface height fluctuation of a projection surface, an incident angle, and an observation angle; and
configuring a power ratio and a power spectrum density function of each laser source, the plurality of power ratios and power spectrum density functions generating a normalized power spectrum density function of the projection system having the set of desired chromaticity coordinates and a wavelength diversity factor of at least 2 in the expected operational environment.

2. The method of claim 1 , wherein the projection system has a projection path extending between the plurality of laser sources to a projection lens, the projection path including at least one homogenization component.

3. The method of claim 2 , wherein the at least one homogenization component includes a diffuser and at least one of a light pipe and/or a pair of lens arrays.

4. The method of claim 2 , wherein the projection path includes at least one coupling element between the plurality of laser sources and the at least one homogenization component.

5. The method of claim 4 , wherein the coupling element is at least one of a fiber bundle and a mirror.

6. The method of claim 4 , wherein the projection path includes a spatial light modulator between the at least one homogenization component and the projection lens and at least one intermediate optical elements between the at least one homogenization component and the spatial light modulator.

7. The method of claim 1 , wherein the plurality of laser sources includes a group of green channel laser sources to produce a green chromaticity coordinate of the set of desired chromaticity coordinates, a group of red channel laser sources to produce a red chromaticity coordinate of the set of desired chromaticity coordinates, and a set of blue channel laser sources to produce a blue chromaticity coordinate of the set of desired chromaticity coordinates.

8. The method of claim 7 , wherein the set of desired chromaticity coordinates is a set of Rec.2020 chromaticity coordinates.

9. The method of claim 7 , wherein the group of green channel laser sources including a set of at least one semiconductor laser diode and a set of at least one diode pumped solid state laser, the at least one semiconductor laser diode having a power ratio of 0.2 and the at least one diode pumped solid state laser having a power ratio of 0.8.

10. The method of claim 9 , wherein the set of at least one semiconductor laser diode has a center wavelength of 515 nm and the set of at least one diode pumped solid state laser has a center wavelength of 532 nm.

11. The method of claim 10 , herein the set of at least one semiconductor laser diode includes at least two semiconductor laser diodes with a wavelength difference of at least 1.5 nm therebetween and the set of at least one diode pumped solid state laser includes at least two diode pumped solid state lasers with a wavelength difference of at least 0.7 nm therebetween.

12. A projection system, comprising:
an input device configured to receive a set of desired chromaticity coordinates and a set of operational parameters of an expected operational environment, the set of operational parameters including a standard deviation of surface height fluctuation of a projection surface, an incident angle, and an observational angle;
a plurality of laser sources each having an independently configurable power ratio and an independently configurable power spectrum density function;
at least one processor coupled to the input device to receive the set of desired chromaticity coordinates and the set of operational parameters, the at least one processor coupled to the plurality of laser sources to set the plurality of power ratios and the plurality of power spectrum density functions to generate a normalized power spectrum density function of the projection system, the normalized power spectrum density function producing the set of desired chromaticity coordinates and a wavelength diversity factor of at least 2 in the expected operational environment; and
a projection path extending between the plurality of laser sources and a projection lens.

13. The projection system of claim 12 , wherein the projection system includes at least one homogenization component in the projection path.

14. The projection system of claim 13 , wherein the at least one homogenization component includes a diffuser and at least one of a light pipe and/or a pair of lens arrays.

15. The projection system of claim 13 , wherein the projection path includes at least one coupling element between the plurality of laser sources and the at least one homogenization component.

16. The projection system of claim 15 , wherein the coupling element is at least one of a fiber bundle and a mirror.

17. The projection system of claim 15 , wherein the projection path includes a spatial light modulator between the at least one homogenization component and the projection lens and at least one intermediate optical elements between the at least one homogenization component and the spatial light modulator.

18. The method of claim 12 , wherein the plurality of laser sources includes a group of green channel laser sources to produce a green chromaticity coordinate of the set of desired chromaticity coordinates, a group of red channel laser sources to produce a red chromaticity coordinate of the set of desired chromaticity coordinates, and a set of blue channel laser sources to produce a blue chromaticity coordinate of the set of desired chromaticity coordinates.

19. The method of claim 18 , wherein the set of desired chromaticity coordinates is a set of Rec.2020 chromaticity coordinates.

20. The projection system of claim 18 , wherein the group of green channel laser sources includes a set of at least one semiconductor laser diode and a set of at least one diode pumped solid state laser, the at least one semiconductor laser diode having a power ratio of 0.2 and the at least one diode pumped solid state laser having a power ratio of 0.8.

21. The projection system of claim 20 , wherein the set of at least one semiconductor laser diode has a center wavelength of 515 nm and the set of at least one diode pumped solid state laser has a center wavelength of 532 nm.

22. The projection system of claim 21 , wherein the set of at least one semiconductor laser diode includes at least two semiconductor laser diodes with a wavelength difference of at least 1.5 nm therebetween and the set of at least one diode pumped solid state laser includes at least two diode pumped solid state lasers with a wavelength difference of at least 0.7 nm therebetween.

Assignees

• Univ Mcmaster

Inventors

• Ma Qianli
• Xu Chang-Qing

Classifications

• G03B21/2033

  LED or laser light sources · CPC title

• G03B21/206

  Control of light source other than position or intensity · CPC title

• H04N9/3155

  for controlling the light source (light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406) · CPC title

• G02B27/48 Primary

  Laser speckle optics · CPC title

• H04N9/3194

  including sensor feedback · CPC title