Laser illuminated projection displays

• US 7,355,657 B2
• Filed: 12/14/2004
• Issued: 04/08/2008
• Est. Priority Date: 12/14/2004
• Status: Expired due to Fees

• Current Assignee: Coherent Inc (Coherent Corp.)
• Original Assignee: Coherent Inc (Coherent Corp.)
• Inventors: Caprara, Andrea, Reed, Murray K., Chilla, Juan L., Govorkov, Sergei V., Spinelli, Luis A.
• Primary Examiner(s): Natnael; Paulos M.
• Application Number:
  US11/011,075
• Publication Number:
  US 20060125969A1
• Time in Patent Office: 1,211 Days
• Field of Search: 348/744, 348/750, 348/756, 348/757, 348/758, 348/759, 348/760, 348/761, 372/43, 372/39, 372/50, 372/92, 372/102
• US Class Current: 348/744
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

A projection video display includes a light source including an OPS-laser delivering laser radiation in multiple transverse modes (a multiple-transverse-mode OPS-laser). The display includes a spatial light modulator for spatially modulating the radiation from the multiple-transverse-mode OPS-laser in accordance with a portion of an image to be displayed. Projection optics project the spatially modulated light on a screen on which the image is to be displayed. In one example the OPS-laser is a diode-laser array pumped OPS-laser and is one of three lasers, one delivering red light, one delivering blue light, and the other delivering green light. The lasers are time modulated such that the spatial light modulator receives light from each of the lasers separately. The OPS laser is directly time modulated by periodically turning the diode-laser array on and off.

Claims

1. A projection display, comprising:

at least one, optically pumped semiconductor (OPS) laser, said laser including a semiconductor gain medium located with a resonator including one mirror spaced from the gain medium, said gain medium being optically pumped and wherein the resonator is configured so that TEM₀₀ mode size at the gain medium is smaller than the pump beam spot size at the gain medium so that the laser delivers laser radiation in multiple transverse modes in both orthogonal (X/Y) axes perpendicular to the propagation axis of the delivered laser radiation;

a spatial light modulator for spatially modulating said radiation from said OPS-laser in accordance with a component of an image to be displayed; and

projection optics for projecting said spatially modulated light onto a screen on which said image is to be displayed.

2. The display of claim 1, wherein said OPS-laser delivers one of red, green, or blue radiation.

3. The display of claim 1, wherein there are first and second OPS-lasers each thereof delivering laser radiation in multiple transverse modes.

4. The display of claim 3, wherein said first multiple-transverse-mode OPS-laser delivers blue radiation, and said second multiple-transverse-mode OPS-laser delivers green radiation.

5. The display of claim 4, wherein said first and second multiple-transverse-mode OPS-lasers are frequency-doubled lasers generating fundamental radiation having a wavelength twice the wavelength of the delivered radiation.

6. The display of claim 1, wherein said OPS-laser delivers said multiple-transverse mode radiation in a beam having a divergence M² between about 2 and 20.

7. The display of claim 1, wherein said spatial light modulator is one of a group of spatial light modulators consisting of a grating light-valve modulator, a digital light processor, a grating electromechanical system, or a liquid crystal on silicon modulator.

8. The display of claim 7, wherein said spatial light modulator is a digital light processor.

9. A projection display, comprising:

a spatial light modulator;

first, second, and third lasers for generating and delivering respectively a red light beam, a green light beam and a blue light beam, at least one of said first, second, and third lasers being an optically pumped semiconductor laser;

an optical arrangement for delivering said red, green and blue light beams to said spatial light modulator, said spatial light modulator being arranged to amplitude modulate said red, green and blue light beams in accordance with red, green, and blue components of an image to be displayed;

a time modulation arrangement for periodically interrupting delivery of said red, green, and blue light beams to said spatial light modulator in a manner such that said light beams are received and spatially modulated separately by said spatial light modulator; and

wherein said time modulation arrangement includes periodically interrupting said optical pumping of said optically pumped semiconductor laser, thereby periodically interrupting generation of said light beam provided thereby.

10. The display of claim 9, wherein said optically pumped semiconductor laser is pumped by light from a diode-laser array, and said periodic interruption of said optical pumping is effected by periodically turning said diode-laser array on and off.

11. The display of claim 10, wherein light from said diode-laser array is delivered to said optically pumped semiconductor laser via an optical fiber bundle.

12. The display of claim 10, wherein light from said diode-laser array is focused directly into said optically pumped semiconductor laser by means of a plurality of lens elements.

13. The display of claim 9, wherein said optically pumped semiconductor laser delivers said light beam in multiple transverse modes.

14. The display of claim 9, wherein said optically pumped semiconductor laser is a frequency-doubled, optically pumped semiconductor laser.

15. The display of claim 9, wherein said spatial light modulator is one of a group of spatial light modulators consisting of, a grating light-valve modulator, a digital light processor, a grating electromechanical system, or a liquid crystal on silicon modulator.

16. A projection display, comprising:

first, second, and third lasers for generating and delivering respectively a red light beam, a green light beam and a blue light beam, at least one of said first, second, and third lasers being an optically pumped semiconductor laser, and each of said beams having an original beam divergence;

an optical arrangement for directing said red, blue, and green, beams along a common path;

a first lens;

a scanning arrangement for scanning said red, green and blue beams in said common path in a particular pattern over said first lens, such that averaged over time each of said beams has an apparent beam divergence greater than said original divergence thereof, said first lens being arranged to direct said scanned beams into a beam homogenizer;

a spatial light modulator, said spatial light modulator arranged to receive said red green and blue light beams homogenized by said beam homogenizer spatially modulate said homogenized beams in accordance with a red, green or blue portion of an image to be displayed; and

projection optics for projecting said homogenized, spatially modulated, red, green, and blue beams onto a screen on which said image is to be displayed.

17. The display of claim 16, wherein said scanning arrangement includes a rotatable prism disposed in said common beam path in a manner such that when said prism is rotated said beams are scanned in an annular pattern over said first lens.

18. The display of claim 16, wherein said scanning arrangement includes a fixed mirror disposed in said common beam path, and directing said common path onto a rotatable mirror arranged at an angle to a rotation axis thereof in a manner such that when said rotatable mirror is rotated said beams are scanned in an annular pattern over said first lens.

19. The display of claim 16, wherein said scanning arrangement includes first and second rotatable mirrors, each thereof inclined to a rotation axis thereof and having a second lens therebetween, said first rotatable mirror being disposed on said common path of said beams in a manner such that when said first mirror is rotated said red, green, and blue beams are scanned over said second lens in a first annular pattern, said second lens being arranged to focus said first annular pattern onto said second rotatable mirror, and said second rotatable mirror being arranged such that rotation thereof, while said first mirror is rotating causes said first annular pattern to be scanned over said first lens in a second annular pattern.

20. The display of claim 16, wherein said scanning arrangement includes first and second rotatable faceted scanning wheels having a second lens therebetween, said facets of said first rotatable scanning wheel being disposed on said common path of said beams in a manner such that when said first scanning wheel is rotated said red, green, and blue beams are scanned over said second lens in a first transverse axis, said second lens being arranged to focus said scanned beams onto facets of said second rotatable scanning wheel, and said second scanning wheel being arranged such that rotation thereof, while said first scanning wheel is rotating, causes said focused scanned beams be scanned over said first lens in a second axis perpendicular to said first axis, whereby said red, green blue beams are scanned in a raster pattern over said first lens.

21. The display of claim 16, wherein said scanning arrangement includes first and second reciprocally rotatable galvanometer mirrors having a second lens therebetween, said first galvanometer mirror being disposed on said common path of said beams in a manner such that when said first galvanometer mirror is rotated said red, green, and blue beams are scanned over said second lens in a first axis, said second lens being arranged to focus said scanned beams onto said second galvanometer mirror, and said second galvanometer mirror being arranged such that rotation thereof causes said focused scanned beams be scanned over said first lens in a second axis perpendicular to said first axis, whereby said red, green blue beams are scanned in a raster pattern over said first lens.

22. The display of claim 16, wherein said scanning arrangement includes a rotatable faceted scanning wheel rotatable about a rotation axis, facets of said scanning wheel being inclined at a plurality of different angles to said rotation axis thereof, and said scanning wheel being disposed on said common path of said beams in a manner such that when said scanning wheel is rotated said beams are scanned by said facets in mutually perpendicular axes in a raster pattern over said first lens.

23. A projection display, comprising:

first, second, and third lasers for generating and delivering respectively a red light beam, a green light beam and a blue light beam, at least one of said first, second, and third lasers being an optically pumped semiconductor laser, and each of said beams having an original beam divergence;

an optical arrangement for directing said red, blue, and green, beams along a common path;

a first lens;

a scanning arrangement for scanning said red, green and blue beams in said common path in a particular pattern over said first lens, such that averaged over time, each of said beams has an apparent beam divergence greater than said original divergence thereof, said first lens being arranged to direct said scanned beams into a beam homogenizer;

a spatial light modulator, said spatial light modulator arranged to receive said red green and blue light beams homogenized by said beam homogenizer spatially modulate said homogenized beams in accordance with a red, green or blue portion of an image to be displayed;

a screen for displaying said image;

projection optics for projecting said homogenized, spatially modulated, red, green, and blue beams onto said screen; and

wherein said screen includes a transparent sheet having a plurality of raised surfaces features for directing light in said beams incident thereon in a plurality of directions, each of said features having a dimension that is greater than the coherence radius of said light on said screen but is not resolvable by a viewer at normal viewing distance from said screen.

24. A projection display, comprising:

first, second, and third lasers for generating and delivering respectively a red light beam, a green light beam and a blue light beam, at least one of said first, second, and third lasers being an optically pumped semiconductor laser, and each of said beams having an original beam divergence;

an optical arrangement for directing said red, blue, and green, beams along a common path;

a first lens;

a scanning arrangement for scanning said red, green and blue beams in said common path in a particular pattern over said first lens, such that averaged over time each of said beams has an apparent beam divergence greater than said original divergence thereof, said first lens being arranged to direct said scanned beams into a beam homogenizer;

a spatial light modulator, said spatial light modulator arranged to receive said red green and blue light beams homogenized by said beam homogenizer spatially modulate said homogenized beams in accordance with a red, green or blue portion of an image to be displayed;

a screen for displaying said image;

projection optics for projecting said homogenized, spatially modulated, red, green, and blue beams onto said screen; and

wherein said screen includes a transparent cell containing a liquid having a plurality of particles in suspension therein said particles being sufficiently small to scatter light from said red, green and blue beams and being in continuous random motion with respect to each other while said image is being displayed.

25. The display of claim 24, wherein said screen includes at least one agitating device disposed at a periphery of said cell for maintaining said particles in said continuous random motion.

26. The display of claim 24, wherein said particles have a maximum dimension less than about 10 micrometers.

27. The display of claim 24, wherein said random motion of said particles is Brownian motion.

28. The display of claim 27, wherein said particles have a maximum dimension less than one micrometer.

29. Display apparatus for displaying a projected image, comprising:

a light source for providing light for forming the projected image, said light source including at least one, optically pumped semiconductor (OPS) laser, said laser including a semiconductor gain medium located with a resonator including one mirror spaced from the gain medium, said gain medium being optically pumped and wherein the resonator is configured so that TEM₀₀ mode size at the gain medium is smaller than the pump beam spot size at the gain medium so that the laser delivers laser radiation in multiple transverse modes in both orthogonal (X/Y) axes perpendicular to the propagation axis of the delivered laser radiation.