Micro-projection device with anti-speckle imaging mode

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 projection surface;

said system including at least one pixel displacement unit 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 projection surface, wherein said pixel displacement unit is arranged for controlling the coherent light source so as to modify the phase of laser pulses sent by said at least one coherent light source, so that the position of said pulses on said projection surface is modified by said phase modification.

2. A micro-projection 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 projection 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.

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

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

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

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

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

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

10. A micro-projection system according to claim 4 , wherein said pixel displacement unit is a thermally actuated displacement unit which further comprises a MEMS mirror heating and cooling system.

11. 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 projection surface, by controlling light source so as to modify the phase of laser pulses sent by said at least one coherent light source.

12. A method for reducing speckle in a laser micro-projection system according to claim 11 , wherein, in a single frame, a plurality of pixels are moved with respect to the others.

13. A method for reducing speckle in a laser micro-projection system according to claim 11 , wherein, in a plurality of successive frames, at least one frame is moved with respect to other frames.

14. A method for reducing speckle in a laser micro-projection system according to claim 11 , wherein pixel displacement is at least 10% of the pixel size.

15. A method for reducing speckle in a laser micro-projection system according to claim 11 , wherein pixel displacement is provided by modifying the temporal position of corresponding laser pulses between successive frames.