Optical-radiation projection

• US 20070116405A1
• Filed: 05/10/2006
• Published: 05/24/2007
• Est. Priority Date: 05/11/2005
• Status: Abandoned Application

• Current Assignee: Arete Associates
• Original Assignee: Arete Associates
• Inventors: Kane, David, Daiker, Jeff
• Application Number:
  US11/431,209
• Publication Number:
  US 20070116405A1
• Time in Patent Office: Days
• US Class Current: 385/18
• 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 27/141 using dichroic mirrors
• CPC Class Codes: G02B 27/28 for polarising used in stereoscopes G02B30/25
• 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

This projection method and apparatus use laser illumination, beam steering with a microelectromechanical-system (“MEMS”) mirror or array, and an afocal lens to magnify the MEMS deflections. In some preferred forms of the invention a beam splitter—preferably of polarization type—cooperates with a quarter-wave plate to transmit the radiation beam in one pass through the splitter and reflect the beam in another pass, thus cleanly separating the source subassembly from the processing and output subassemblies.

Claims

1. Image projecting apparatus comprising:

at least one radiation source forming a radiation beam;

a MEMS mirror, or mirror array, deflecting the beam;

an afocal optic magnifying the beam deflection;

a beam splitter for directing the beam along;

a first path from the at least one source to the mirror or array, and

a second path from the mirror or array to the optic; and

means for introducing at least one constant phase delay, substantially uniform across the splitter, between the first and second paths.

2. The apparatus of claim 1, wherein:

the beam splitter is a polarization beam splitter;

due to the splitter, both the first and second paths are roughly normal to the mirror or array; and

the introducing means comprise a fixed retarder through which both the first and second paths pass.

3. The apparatus of claim 2, wherein:

the retarder comprises a quarter-wave plate; and

the beam is polarized;

wherein the two passes through the plate, in the two paths, reverse the interaction of the beam with the splitter, with respect to transmission and reflection.

4. The apparatus of claim 3, wherein:

in one pass the polarizer transmits the beam; and

in the other pass the splitter reflects the beam.

5. The apparatus of claim 3, wherein:

in the first pass the polarizer transmits the beam; and

in the second pass, due to said reversal, the splitter reflects the beam.

6. The apparatus of claim 3, wherein:

in the first pass the polarizer reflects the beam; and

in the second pass, due to said reversal, the splitter transmits the beam.

7. The apparatus of claim 6:

wherein the source comprises at least three light sources at different wavelengths; and

further comprising;

means for combining radiation from the three sources to form a single beam for deflection by the mirror or array,

means for generating, receiving or storing data defining an image,

means for applying image data from the generating-receiving-or-storing means to control the deflection by the mirror or array.

8. The apparatus of claim 7, wherein:

the applying means comprise means for controlling the deflection to sweep the beam in a raster or vector pattern to form a projected image.

9. The apparatus of claim 7, wherein:

the sources comprise a source of visible radiation.

10. The apparatus of claim 7, wherein:

the sources comprise a source of ultraviolet radiation.

11. The apparatus of claim 7, wherein:

the sources comprise a source of infrared radiation.

12. Image projecting apparatus comprising:

means for generating, receiving or storing data defining an image;

at least three radiation sources at different wavelengths, with radiation beams combining to form a polarized radiation beam;

a MEMS mirror, or mirror array, deflecting the beam;

an afocal optic magnifying the beam deflection;

a polarization beam splitter for directing the combined beam on a first path from the sources roughly normal to the mirror or array, and on a second path roughly normal from the mirror or array to the optic;

a quarter-wave plate for introducing a total phase delay of substantially one-half wave between the first and second paths;

wherein the splitter reflects the beam in one of the two paths and transmits the beam in the other of the two paths; and

means for applying image data from the generating-receiving-or-storing means to control the deflection by the mirror or array in a raster or vector pattern to form a projected image.

13. The apparatus of claim 12, wherein:

the sources comprise a source of visible radiation.

14. The apparatus of claim 12, wherein:

the sources comprise a source of ultraviolet radiation.

15. The apparatus of claim 12, wherein:

the sources comprise a source of infrared radiation.

16. A method for imaging a scene;

said method comprising the steps of;

projecting a radiation beam from at least one radiation source to a MEMS mirror, or mirror array;

operating the mirror or array to deflect the beam;

transmitting the deflected beam through an afocal optic to magnify the beam deflection;

passing the beam through a beam splitter to direct the beam along;

a first path from the at least one source to the mirror or array, and

a second path from the mirror or array to the optic; and

introducing at least one constant phase delay, substantially uniform across the splitter, between the first and second paths.

17. The method of claim 16, wherein:

the passing step comprises passing the beam twice through a polarization beam splitter;

due to the splitter, the first and second paths are roughly normal to the mirror or array; and

the introducing step comprises passing the beam twice through a quarter-wave plate.

18. The apparatus of claim 17, wherein:

in one pass the polarizer transmits the beam; and

in the other pass the splitter reflects the beam.

19. The apparatus of claim 18, wherein:

in the first pass the polarizer reflects the beam; and

in the second pass, due to said reversal, the splitter transmits the beam.