Infrared imager using room temperature capacitance sensor

• US 6,249,001 B1
• Filed: 04/08/1999
• Issued: 06/19/2001
• Est. Priority Date: 03/27/1996
• Status: Expired due to Term

• Current Assignee: SRI International, Inc.
• Original Assignee: Sarnoff Corporation (SRI International, Inc.)
• Inventors: Levine, Peter Alan, Amantea, Robert, Sauer, Donald Jon, Martinelli, Ramon Ubaldo
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US09/300,986
• Time in Patent Office: 803 Days
• Field of Search: 250/332, 250/338.1, 250/340, 250/336.1, 374/205
• US Class Current: 250/338.1
• CPC Class Codes: C07D 405/06 linked by a carbon chain containing only aliphatic carbon atoms
• CPC Class Codes: G01J 5/34 using capacitors, e.g. pyroelectric capacitors
• CPC Class Codes: G01J 5/40 using bimaterial elements
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

An infrared imager includes an array of capacitance sensors that operate at room temperature. Each infrared capacitance sensor includes a deflectable first plate which expands due to absorbed thermal radiation relative to a non-deflectable second plate. In one embodiment each infrared capacitance sensor is composed of a bi-material strip which changes the position of one plate of a sensing capacitor in response to temperature changes due to absorbed incident thermal radiation. The bi-material strip is composed of two materials with a large difference in thermal expansion coefficients.

Claims

1. A method of detecting radiation, comprising the steps of:

providing a microcantilever within a substrate, including the steps of;

providing a base for coupling said microcantilever to said substrate and providing a thermal isolation element for isolating said microcantilever from said substrate wherein the microcantilever has at least one physical property that is affected by radiation;

exposing said microcantilever to a source of radiation;

monitoring a radiation-induced change in the at least one physical property of the microcantilever to determine a magnitude of the change; and

determining a measure of the radiation from the magnitude of the radiation-induced changes in the at least one physical property of the microcantilever.

2. The method according to claim 1, wherein the monitoring step includes monitoring radiation-induced bending of the microcantilever.

3. The method as in claim 1, wherein said microcantilever includes a film made of a material which interacts with the microcantilever to form a bi-material element.

4. The method as in claim 3, wherein said bi-material element heats when exposed to radiation and said change in the at least one physical property comprises bending.

5. A sensor for detecting radiation in response to a radiation-induced change, comprising:

a microcantilever formed within a substrate and including at least one physical property that is affected by radiation, a base coupling said microcantilever to said substrate, and a thermal isolation element isolating said microcantilever from said substrate; and

means for determining a measure of a radiation-induced change in the at least one physical property;

wherein said radiation-induced change comprises a change in the at least one physical property of the microcantilever.

6. The sensor as in claim 5, wherein said microcantilever further includes a film made of a material which interacts with the microcantilever to form a bi-material element.

7. The sensor as in claim 6, wherein said bi-material element heats when exposed to radiation and said change in the at least one physical property comprises bending.