Illumination system to eliminate laser speckle and projection system employing the same

• US 7,762,673 B2
• Filed: 02/04/2009
• Issued: 07/27/2010
• Est. Priority Date: 12/15/2004
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Sung-ha, Dho, Sang-whoo
• Primary Examiner(s): Dowling; William C
• Application Number:
  US12/365,236
• Publication Number:
  US 20090141251A1
• Time in Patent Office: 538 Days
• Field of Search: 353/46, 353/48, 353/49, 353/94, 359/196.1, 359/197.1, 359/204.1, 359/209.1, 359/213.1, 359/214.1, 362/551, 362/553, 362/554, 362/561, 385/115, 385/116, 385/901
• US Class Current: 353/50
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 27/0994 Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 5/1866 Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: G03H 2227/03 Means for moving one component G03H1/0476, G03H2001/2695 take precedence
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

An illumination system designed to remove laser speckle and a projection system including the same. The illumination system includes a laser light source having at least one laser, a diffractive optical element to divide a laser beam emitted from the laser light source into a plurality of sub-beams and to periodically move in such a way as to temporally average the speckle of the laser beam, and an optical fiber bundle including a plurality of fibers with the same length to divide the sub-beams into smaller sub-beams. The illumination system divides the laser beam emitted from the laser light source into sub-beams and temporally or spatially averages the sub-beams, thereby effectively reducing or removing laser speckle. The projection system employing the illumination system can provide improved image quality.

Claims

1. An illumination system to remove speckle of a laser beam, the illumination system comprising:

a laser light source having at least one laser to emit a laser beam;

an optical fiber bundle including a plurality of fibers with the same length to divide the laser beam emitted from the laser light source into a plurality of sub-beams; and

a vibrator to vibrate to temporally average the plurality of sub-beams such that an image is formed according to the sub-beams.

2. The illumination system of claim 1, wherein the vibrator comprises:

a reflecting mirror; and

a piezoelectric element to vibrate the reflecting mirror.

3. The illumination system of claim 1, further comprising:

a beam-shaping unit disposed after the optical fiber bundle along a path of the laser beam to convert a cross-section of each of the plurality of sub-beams into a predetermined shape of a display device.

4. The illumination system of claim 3, wherein the beam-shaping unit comprises a light pipe.

5. The illumination system of claim 3, wherein the beam-shaping unit includes a collimating lens and first and second fly-eye lens arrays.

6. The illumination system of claim 4, wherein the beam-shaping unit includes a collimating lens and a beam-shaping diffractive optical element having a predetermined diffractive pattern.

7. A projection system to remove speckle of a laser beam, the projection system comprising:

a laser light source having at least one laser to emit a laser beam;

an optical fiber bundle including a plurality of fibers with the same length to divide the laser beam emitted from the laser light source into a plurality of sub-beams;

a beam-shaping unit to shape the plurality of sub-beams output by the optical fiber bundle;

a vibrator to vibrate to temporally average the plurality of sub-beams;

a display device to produce an image using the plurality of sub-beams temporally averaged by the vibrator;

a screen; and

a projection lens unit to enlarge and project the image produced by the display device onto the screen.

8. The projection system of claim 7, wherein the vibrator comprises:

a reflecting mirror; and

a piezoelectric element to vibrate the reflecting mirror.

9. The projection system of claim 7, wherein the beam-shaping unit comprises a light pipe.

10. The projection system of claim 9, further comprising:

a condensing lens disposed between the optical fiber bundle and the beam-shaping unit.

11. The projection system of claim 7, wherein the beam-shaping unit includes a collimating lens and first and second fly-eye lens arrays.

12. The projection system of claim 7, wherein the beam-shaping unit includes a collimating lens and a beam-shaping diffractive optical element having a diffractive pattern.

13. The projection system of claim 7, wherein the display device comprises one of a transmissive liquid crystal display (LCD), a Liquid Crystal on Silicon (LCoS) display, a Deformable Micromirror Device (DMD), and a Grating Light Valve (GLV).