Micro-mechanical optical shutter

• US 5,459,602 A
• Filed: 10/29/1993
• Issued: 10/17/1995
• Est. Priority Date: 10/29/1993
• Status: Expired due to Fees

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Sampsell, Jeffrey B.
• Primary Examiner(s): Dzierzynski, Paul M.
• Assistant Examiner(s): Phan, James
• Application Number:
  US08/148,073
• Time in Patent Office: 718 Days
• Field of Search: 359/227, 359/230, 359/233, 359/234, 359/236, 359/559, 359/561, 310/40 R, 310/42, 310/90, 310/90.5, 310/268, 310/309, 250/232, 250/233, 156/651, 156/652
• US Class Current: 359/234
• CPC Class Codes: G02B 26/04 by periodically varying the intensity of light, e.g. using choppers shutters, diaphragms for cameras G03B9/00; devices for eliminating or reducing the effect of flicker in projection systems G03B21/40
• CPC Class Codes: H02N 1/004 in which a body is moved along a path due to interaction with an electric field travelling along the path

Abstract

A micro-optical shutter array (92, 102) having a number of tiny shutters (10), which revolve so as to intermittently block light from a via (12), and which may be operated in either a stepping or continuous motion. The array (92, 102) may be batch manufactured using integrated circuit fabrication techniques. For each shutter, a via (12) is etched through a substrate (11). A rotor (13, 43, 53, 63) with at least one opening is fabricated over the via (12), such that as the rotor (13, 43, 53, 63) turns, radiation transmitted through the via (12) is selectively blocked or not blocked.

Claims

1. An array of micro-optical shutters, each for intermittently blocking the passage of radiation, comprising:

a substrate having a plurality of vias through which said radiation may pass, each via associated with a shutter;

each shutter comprising a rotor hub fabricated upon said substrate, a rotor fabricated above and spaced from said substrate for revolving around said rotor hub in a plane parallel to said substrate, said rotor having at least one opening that is aligned with at least one of said vias for a part of each revolution of said rotor, and a set of stator poles fabricated above said substrate around the perimeter of said rotor to which voltage may be applied for providing a rotor torque.

2. The array of claim 1, wherein each said rotor has a set of radial spokes.

3. The array of claim 1, wherein each said rotor is generally disk-shaped.

4. The array of claim 1, wherein each said rotor has a number of teeth around its perimeter.

5. The array of claim 1, wherein each said rotor is in the order of 100 microns in diameter.

6. The array of claim 1, wherein each said rotor has at least one filter for changing the wavelength of said light over said at least one opening.

7. The array of claim 1, wherein each said rotor has one or more dished portions of its underside.

8. The array of claim 1, wherein said vias are cylindrical in shape and of a size suitable for securing an optical fiber.

9. The array of claim 1, wherein said via are cone-shaped.

10. The array of claim 1, further comprising a control unit for controlling the timing of said voltage applied to said stator poles.

11. A method of manufacturing an array of micro-optical shutters, comprising the steps of:

etching vias through a substrate, each via associated with one of said shutters;

filling said vias with a sacrificial material;

sequentially depositing layers of etchable material on said substrate and etching rotors, rotor hubs, and stators from said etchable material, such that each rotor is rotatable around a rotor hub when voltage is applied to said stators, wherein each said rotor has at least one opening that may be aligned with an associated via during one revolution of said rotor; and

removing said sacrificial material from said vias.

12. The method of claim 11, further comprising the steps of depositing a filter material over said at least one opening.

13. The method of claim 11, wherein said substrate is silicon and said step of etching vias is performed with a orientation directed etch, such that said vias are cone-shaped.

14. The method of claim 11, wherein said step of etching vias is performed such that said vias are cylindrical in shape and have a diameter suitable for inserting an optical fiber.

15. The method of claim 11, further comprising the step of etching a dished portion on the underside of each said rotor.

16. An optical correlation system for comparing multiple reference images to one or more acquired image, comprising:

an array of micro-optical shutters fabricated on a substrate having a plurality of vias, each shutter comprising a rotor hub fabricated upon said substrate, a rotor fabricated above and spaced from said substrate for revolving around said rotor hub in a plane parallel to said substrate, said rotor having at least one opening that is aligned with one of said vias for a part of each revolution of said rotor, and a set of stator poles fabricated above said substrate around the perimeter of said rotor and substantially co-planar to said rotor, to which voltage may be applied for providing a rotor torque;

an array of lenses, each lens for receiving light transmitted through a via when a corresponding shutter is open;

a reference film having an array of reference images, each image associated with one of said shutters;

a first transform lens for receiving a reference image from said reference film and for transforming said image into its Fourier transform image;

a spatial light modulator having an array of reflective pixel elements, for displaying an image representing the complex conjugate of the Fourier transform of the acquired image and for reflecting said Fourier transform image of said reference image;

a second transform lens for receiving the combination of the image displayed by said spatial light modulator and the image reflected by said spatial light modulator, and for Fourier transforming the combined images; and

a sensor for receiving the image transmitted by said second transform lens.

17. The optical correlation system of claim 16, wherein said vias are cylindrical in shape for inserting an optical fiber.

18. The optical correlation system of claim 16, wherein said vias are cone-shaped and further comprising an array of focussing lenses for focussing light from a source to each of said shutters.