Illumination system eliminating laser speckle and projection TV employing the same

• US 20060109553A1
• Filed: 11/21/2005
• Published: 05/25/2006
• Est. Priority Date: 11/19/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Dho, Sangwhoe, Serafimovich, Pavel, Cheong, Byoungho, Kim, Sungha
• Granted Patent: US 7,697,079 B2
• Time in Patent Office: Days
• US Class Current: 359/565
• CPC Class Codes: G02B 27/46 Systems using spatial filters
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 5/7416 involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal

Abstract

Provided are an illumination system and a projection TV employing the same. The illumination system includes: a laser light source including a plurality of lasers which emit laser beams including a plurality of beamlets; a first diffractive optical element which separates the laser beams according to wavelength and which focuses the separated beams onto different segments of a second refractive optical element; and the second diffractive optical element which focuses and superimposes a plurality of beamlets, of the laser beams transmitted by the first diffractive optical element, in order to spatially average the laser beams and to eliminate laser speckle.

Claims

1. An illumination system comprising:

a laser light source including a plurality of lasers which emit laser beams including a plurality of beamlets;

a first diffractive optical element which separates the laser beams according to wavelength and which focuses the separated beams onto different segments of a second refractive optical element; and

the second diffractive optical element which focuses and superimposes a plurality of beamlets, of the laser beams transmitted by the first diffractive optical element, in order to spatially average the laser beams and to eliminate laser speckle.

2. The system of claim 1, wherein the plurality of lasers emit beams along the same optical axis.

3. The system of claim 1, wherein the first diffractive optical element focuses the laser beams emitted by the laser light source so that the focused beams have concentric annular profiles.

4. The system of claim 1, wherein the second diffractive optical element comprises diffractive patterns corresponding to the different segments onto which the separated beams are focused.

5. The system of claim 1, wherein the second diffractive optical element shapes the cross-section of the laser beams transmitted by the first diffractive optical element into a predetermined shape.

6. A projection television comprising:

a laser light source unit including a plurality of lasers which emit laser beams including a plurality of beamlets;

a first diffractive optical element which separates the laser beams according to wavelength and which focuses the separated beams onto different segments of a second diffractive optical element according to wavelength;

the second diffractive optical element which focuses and superimposes a plurality of beamlets, of the laser beams transmitted by the first diffractive optical element, in order to spatially average the laser beams and to eliminating laser speckle;

a display device which forms an image using the laser beams transmitted by the second diffractive optical element; and

a projection lens unit which enlarges and projects the image onto a screen.

7. The television of claim 6, wherein the plurality of lasers emit beams along the same optical axis.

8. The television of claim 6, wherein the first diffractive optical element focuses the laser beams emitted by the laser light source so that the focused beams have a concentric annular profiles.

9. The television of claim 6, wherein the second diffractive optical element comprises diffractive patterns corresponding to the different segments onto which the separated beams are focused.

10. The television of claim 6, wherein the second diffractive optical element shapes the cross-section of the laser beams transmitted by the first diffractive optical element to match the geometry of the display device.

11. The television of claim 6, wherein the display device is one selected from the group consisting of a transmissive liquid crystal display, a liquid crystal on silicon display, a deformable micromirror device, and a grating light valve.