MICRO-PROJECTION DEVICE WITH ANTIS-PECKLE IMAGING MODE

• US 20130235354A1
• Filed: 04/28/2010
• Published: 09/12/2013
• Est. Priority Date: 04/28/2010
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Lemoptix Sa (Intel Corporation)
• Inventors: Kilcher, Lucio, Abele, Nicolas, Khechana, Faouzi
• Granted Patent: US 8,998,424 B2
• Time in Patent Office: Days
• US Class Current: 353/52
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G03B 21/16 Cooling; Preventing overheating
• 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

Abstract

A micro-projection system for projecting light on a projection surface (104), comprising: at least one coherent light source (101); optical elements (102, 108, 109) in the optical path between said coherent light source and said projection surface; said optical elements including at least one reflective member (102) actuated by a drive signal for deviating light from said light source so as to scan a projected image onto said projecting surface; said optical elements including at least one pixel displacement unit (106) for providing a displacement signal synchronized with the image scanning signal so as to reduce speckle onto said projecting surface. The corresponding method for reducing speckle is also provided.

Claims

1. A micro-projection system for projecting light on a projection surface, comprising:

at least one coherent light source;

optical elements in the optical path between said coherent light source and said projection surface;

said optical elements including at least one reflective member actuated by a drive signal for deviating light from said light source so as to scan a projected image onto said projecting surface;

said system including at least one pixel displacement unit wherein said pixel displacement unit provides a signal superposed to the drive signal for displacing the position of the pixel with respect to the position of a corresponding pixel in another image frame, so as to reduce speckle onto said projecting surface.

2. A micro-system according to claim 1, wherein said pixel displacement unit is arranged for providing a displacement signal synchronized with the image scanning signal so as to reduce speckle onto said projecting surface.

3. A micro-projection system according to claim 1, wherein said pixel displacement unit is adapted to provide a displacement of at least a portion of a first image frame with respect to other image frames in order to reduce speckle.

5. A micro-projection system according to claim 1, wherein said reflective member is a MEMS type scanning mirror and said pixel displacement unit is connected to said scanning mirror.

6. A micro-projection system according to claim 1, wherein said pixel displacement unit is connected to an additional optical element provided in the optical path.

7. A micro-projection system according to claim 5, wherein said additional element is a mirror being adapted to provide said displacement.

8. A micro-projection system according to claim 5, wherein said additional element is a reflective membrane.

12. A micro-system according to claim 1, wherein said pixel displacement unit is arranged for modifying the phase of laser pulses sent by said at least one coherent light source,

wherein said laser pulses are deviated by a MEMS type scanning mirror,

so that the position of said pulses on said projection surface is modified by said phase modification.

14. A method for reducing speckle in a laser micro-projection system according to claim 12, wherein, in a single frame, a plurality of pixels are moved with respect to the others.

15. A method for reducing speckle in a laser micro-projection system according to claim 12, wherein, in a plurality of successive frames, at least one frame is moved with respect to other frames.

16. A method for reducing speckle in a laser micro-projection system according to claim 12, wherein pixel displacement is at least 0, 1 times of the pixel size.

18. A method for reducing speckle in a laser micro-projection system according to claim 12, wherein pixel displacement is provided by modifying the temporal position of corresponding laser pulses between successive frames.

4. (canceled)

9. A micro-projection system according to claim 4, wherein said pixel displacement unit comprises a magnetic, thermal, piezo-electric, or electrostatic generation unit.

10. A micro-projection system according to claim 4, wherein said pixel displacement unit comprises a rotating micro-mirror having a substantially rough surface.

11. A micro-projection system according to claim 4, wherein said pixel displacement unit comprises a MEMS mirror heating and cooling system.

13. A method for reducing speckle in a laser micro-projection system, comprising:

providing a plurality of successive image frames with at least one coherent light source towards a target;

providing a displacement of at least a portion of a first image frame with respect to the same or another image frame so as to reduce speckle onto said projecting surface, wherein pixel displacement is provided by a pixel displacement unit (106) either connected to an optical element of the micro-projection system or electronically cooperating with a scanning mirror drive unit for sending a displacement signal synchronized with the image scanning signal so as to reduce speckle onto said projecting surface.

17. (canceled)