INFRARED DETECTOR AND METHOD

• US 20080185523A1
• Filed: 12/20/2007
• Published: 08/07/2008
• Est. Priority Date: 12/21/2006
• Status: Active Grant

• Current Assignee: Los Alamos National Security LLC (Government of the United States of America)
• Original Assignee: Los Alamos National Security LLC (Government of the United States of America)
• Inventors: SMITH, James Lawrence, OPEIL, Cyril P., LASHLEY, Jason Charles
• Granted Patent: US 7,687,775 B2
• Time in Patent Office: Days
• US Class Current: 250/338.2
• CPC Class Codes: G01J 2005/345 Arrays
• CPC Class Codes: G01J 5/0806 Focusing or collimating elements, e.g. lenses or concave mirrors
• CPC Class Codes: G01J 5/0875 Windows; Arrangements for fastening thereof
• CPC Class Codes: G01J 5/34 using capacitors, e.g. pyroelectric capacitors
• CPC Class Codes: H10N 15/10 Thermoelectric devices using thermal change of the dielectric constant, e.g. working above and below the Curie point

Abstract

An apparatus and method are provided for sensing infrared radiation. The apparatus includes a sensor element that is positioned in a magnetic field during operation to ensure a λ shaped relationship between specific heat and temperature adjacent the Curie temperature of the ferroelectric material comprising the sensor element. The apparatus is operated by inducing a magnetic field on the ferroelectric material to reduce surface charge on the element during its operation.

Claims

1. An infrared sensor apparatus including:

a sensor including at least one infrared sensitive element including a ferroelectric material;

a magnetic field inducing device associated with the at least one element and operable to induce a magnetic field with a magnitude of at least about 3 T on the ferroelectric material; and

a signal generating circuit associated with the element operable to generate a signal indicative of infrared radiation impinging on the at least one said element.

2. The sensor apparatus of claim 1 wherein the ferroelectric material having a Curie temperature of less than about 400K.

3. The sensor apparatus of claim 2 wherein the material including tri-glycine sulfate.

4. The sensor apparatus of claim 1 wherein the sensor including an array of said at least one element.

5. The sensor apparatus of claim 4 wherein the sensor including a lens system operable to receive IR radiation and to project received IR radiation onto the array.

6. A method of sensing infrared radiation, the method including:

providing a sensor element including a ferroelectric material in a configuration effective to sense infrared radiation.

inducing a magnetic field on said sensor element, the field having a magnitude sufficient to reduce surface charge on the sensor element an effective amount; and

providing an output signal indicative of infrared radiation impinging on the sensor element.

7. The method of claim 6 wherein the magnetic field having a magnitude of at least about 3 T.

8. The method of claim 7 wherein the ferroelectric material having a Curie temperature of less than about 400K.

9. The method of claim 6 wherein the surface charge being reduced an amount wherein the ferroelectric material having a λ

shaped specific heat anomaly at about its Curie temperature.

10. A method of testing a ferroelectric material for at least one material property by a

measuring at least one input variable;

measuring at least one response variable;

and during said measuring of at least the response variable, exposing the ferroelectric material to a magnetic field of at least about 3 T.

11. The method of claim 10 wherein the ferroelectric material is at about its Curie temperature during at least a portion of the measuring of the response variable.

12. The method of claim 10 wherein the response variable being indicative of at least one of specific heat, polarization and electrostriction.