High frequency deformable mirror device

• US 6,661,561 B2
• Filed: 03/26/2001
• Issued: 12/09/2003
• Est. Priority Date: 03/26/2001
• Status: Expired due to Fees

• Current Assignee: Creo Products Incorporated
• Original Assignee: Creo Incorporated (Eastman Kodak Company)
• Inventors: Gelbart, Daniel, Fitzpatrick, Glen Arthur
• Primary Examiner(s): Ben, Loha
• Assistant Examiner(s): CHOI, WILLIAM C
• Application Number:
  US09/816,751
• Publication Number:
  US 20020135857A1
• Time in Patent Office: 988 Days
• Field of Search: 359/222, 359/224, 359/230, 359/290, 359/291, 359/298
• US Class Current: 359/291
• CPC Class Codes: B41J 2/465 using masks, e.g. light-switching masks
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

In accordance with the present invention, an array of individually addressable micromachined light reflecting ribbons provide a high speed light valve action by employing a method in accordance with which the ribbons flex about their longer axis under the action of an applied electrostatic field. The ribbons are mounted on pedestals such that the resulting micromechanical structures are substantially symmetrical with respect to a plane along their long axis through the centers of the pedestals and normal to the substrate. This micromechanical arrangement ensures a structure with a high natural frequency, thereby allowing high light valve switching speeds. The particular mode of deformation also ensures a robust structure. The method may be applied in either “bright field” or “dark field” (Schlieren) mode. The particular combination of materials employed allows the method to be used in higher incident power applications such as those encountered in the printing industry. The invention uses the fabrication methods developed for grating light valves to build a deformable mirror light valve combining the fabrication and speed advantages of the former with the simplicity of the latter. Since the ribbons flex about their long axes, the amplitude of tip deflection required to produce a given angular light deflection is much smaller than that required by prior art cantilever devices, which flex about their short axes.

Claims

1. A method for modulating light using a microelectromechanical structure, said microelectromechanical structure comprising a plurality of thin flexible reflective members, said reflective members having elongated shapes, said elongated shapes having a long dimension and a short dimension, said reflective members having at least one reflector surface, said reflector surface having one or more reflective segments and said reflective members capable of being flexed independently of one another, said method comprising directing a beam of light to reflect from said reflective members and flexing a part of said reflective members about an axis parallel to said long dimension to vary a curvature of at least one of the reflective segments,

wherein each of said reflective members is affixed to the rest of said microelectromechanical structure along a line parallel to said long dimension and along a pedestal extending along said long dimension and each of said reflective members projects to either side of the pedestal and wherein said flexing is induced by application of one of the following forces to said reflective members:

electrostatic, magnetic.

2. A deformable mirror device capable of selectively reflecting and modulating an incident beam of light, the device comprising a microelectromechanical structure having a plurality of thin flexible reflective members,

each reflective member having an elongated shape with a long dimension and a short dimension and at least one reflector surface having one or more reflective segments, the one or more reflective segments comprising a reflective layer on the reflective member;

each reflective member being disposed to flex over part of the reflector surface about an axis parallel to said long dimension;

wherein said reflective members are capable of being flexed independently from one another and wherein said reflective members are so positioned relative to an aperture that there exists a particular degree of flexure of any one of said reflective members for which the major fraction of said beam of light reflecting from said one reflective member passes through said aperture.

3. A deformable element for modulating light comprising:

a resilient flexible elongated member having a mirror surface, the member mounted to a substrate and disposed to flex about an axis,

wherein a length of the member in a direction parallel to the axis is greater than a width of the member in a direction perpendicular to the axis, and wherein the member is supported on a pedestal and comprises wings projecting to either side of the pedestal and the mirror surface is on a side of the member away from the pedestal.

4. The deformable element of claim 3 wherein the pedestal is elongated and extends parallel to the axis.

5. The deformable element of claim 4 wherein the wings project symmetrically on either side of the pedestal.

6. The deformable element of claim 4 wherein the substrate comprises a silicon substrate and the pedestal and member are micromachined on the silicon substrate.

7. The deformable element of claim 3 wherein the wings are sufficiently wide and flexible to snap down to touch the substrate.

8. A deformable element according to claim 7 comprising electromagnetic means for flexing the member about the axis.

9. The deformable element of claim 3 wherein the wings are each capable of being flexed independently.

10. The deformable element of claim 3 wherein the mirror surface comprises a layer of a metal on the member.

11. The deformable element of claim 10 wherein the layer comprises at least one reflective layer composed of at least one of:

gold, palladium, platinum, chromium, aluminum, tantalum, and titanium.

12. The deformable element of claim 10 wherein the layer is in electrical contact with a source of a control voltage.

13. A method for modulating light comprising:

providing a light modulator which comprises a plurality of deformable elements as claimed in claim 3,

directing a beam of light to reflect from the mirror surfaces of the resilient flexible elongated members; and

,

flexing one or more of said members about its axis.

14. The method of claim 13 wherein flexing one or more of the members comprises flexing the one or more of the members sufficiently that the one or more of the members has a substantially hyperbolic cosine shape in cross section.

15. The method of claim 13 wherein flexing one or more of the members comprises flexing the one or more of the members sufficiently that edges of the one or more of the members snap down into contact with the substrate.

16. A light modulator comprising an array of deformable elements, each element comprising:

a resilient flexible elongated member having a mirror surface, the member mounted to a substrate and disposed to flex about an axis,

wherein a length of the member in a direction parallel to the axis is greater than a width of the member in a direction perpendicular to the axis, and wherein the members of the deformable elements are so positioned relative to an aperture that there exists a particular degree of flexure of any one of the members for which a major fraction of an incident beam of light reflecting from the one of the members passes through the aperture.

17. A light modulator comprising an array of deformable elements, each element comprising:

a resilient flexible elongated member having a mirror surface, the member mounted to a substrate and disposed to flex about an axis,

wherein a length of the member in a direction parallel to the axis is greater than a width of the member in a direction perpendicular to the axis, and wherein the members of the deformable elements are so positioned relative to a beam stop that there exists a particular degree of flexure of any one of the members for which a major fraction of an incident beam of light reflecting from the one of the members is blocked by the beam stop.