MEMS-actuated color light modulator and methods

• US 6,747,785 B2
• Filed: 10/24/2002
• Issued: 06/08/2004
• Est. Priority Date: 10/24/2002
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Pate, Michael A., Liao, Hung, Chen, Zhizhang
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Dinh, Jack
• Application Number:
  US10/280,995
• Publication Number:
  US 20040080807A1
• Time in Patent Office: 593 Days
• Field of Search: 359/237, 359/290, 359/291, 359/295, 359/298, 359/566, 359/569, 359/571, 250/237.G
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• 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 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/0866 the reflecting means being moved or deformed by thermal means

Abstract

A light modulator has one or more gratings and one or more MEMS actuators operable to move the gratings for selectively modulating light from an input light source. Certain embodiments have a plurality of blazed gratings arranged parallel to a plane and movable linearly parallel to the plane by MEMS actuators. Each of the gratings is individually blazed for light of a selected color such as red, green or blue. Associated with the gratings may be portions providing black and/or white outputs. An aperture spaced apart from the plane allows color(s) selected from an input white-light source to be directed to an output. An array of MEMS-actuated modulation devices provides a color spatial light modulator. Other embodiments have a grating adapted to be tilted by a MEMS actuator, either continuously through a range of angles or to a selected angle of a set of predetermined discrete angles, to direct selected wavelengths diffracted by the grating toward collection optics for a modulated light output. Methods specially adapted for making and using such light modulators are disclosed.

Claims

1. A light modulator for modulating light from a source, said light modulator comprising:

one or more blazed gratings disposed to be illuminated by said light from said source, said one or more blazed gratings being disposed substantially parallel to a first plane,

at least one aperture movably disposed in a second plane, and

at least one MEMS actuator adapted to move said at least one aperture substantially parallel to said second plane to selectively direct light diffracted by said one or more blazed gratings through said at least one aperture.

2. The light modulator of claim 1, wherein said MEMS actuator is adapted to move said at least one aperture by translation along an axis substantially parallel to said first plane.

3. The light modulator of claim 1, wherein said MEMS actuator is adapted to move said at least one aperture by translation along an axis substantially parallel to said second plane.

4. The light modulator of claim 1, wherein said MEMS actuator includes a movable portion integral with said at least one aperture.

5. The light modulator of claim 1, wherein said one or more blazed gratings are formed on a substrate and said MEMS actuator includes a fixed portion integral with said substrate.

6. The light modulator of claim 1, wherein said second plane is substantially parallel to and spaced apart from said first plane.

7. The light modulator of claim 1, comprising three or more blazed gratings, each blazed for a different wavelength.

8. The light modulator of claim 7, wherein said three or more blazed gratings, are blazed for wavelengths corresponding to red, green, and blue light.

9. A method for fabricating a light modulator for modulating light from a source, said method comprising the steps of:

providing a substrate;

forming at least one diffraction grating on said substrate by forming a multiplicity of parallel grooves, said parallel grooves being spaced with a suitable pitch, while blazing said multiplicity of parallel grooves to diffract light of a selected diffraction order; and

forming a MEMS actuator disposed and adapted for establishing a desired spatial relationship between said diffraction grating and an output aperture spaced apart from said substrate, whereby light of at least one selected wavelength may be selectively directed though said output aperture.

10. A light modulator made by the method of claim 9.

11. A method for modulating the color of light from a source, said method comprising the steps of:

disposing a blazed grating to be illuminated by said light from said source and to diffract said light;

disposing a MEMS actuator for varying the spatial relationship between said blazed grating and an output aperture, said MEMS actuator being adapted to vary said spatial relationship in response to electrical signals; and

controlling said electrical signals to direct a selected wavelength of said diffracted light of a selected diffracted order through said output aperture.

12. The method of claim 11, wherein said MEMS actuator is adapted to tilt said blazed grating about an axis parallel to said blazed grating.

13. The method of claim 11, wherein said MEMS actuator is adapted to translate said output aperture in a plane.

14. The method of claim 13, wherein said plane is substantially parallel to said blazed grating.

15. The method of claim 11, wherein said MEMS actuator is adapted to translate said blazed grating in a plane.

16. The method of claim 15, wherein said plane is substantially parallel to said output aperture.