Two F-number, two-color sensor system

• US 20070023663A1
• Filed: 07/27/2005
• Published: 02/01/2007
• Est. Priority Date: 07/27/2005
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Anderson, John, Chen, Chungte
• Granted Patent: US 7,297,951 B2
• Time in Patent Office: Days
• US Class Current: 250/339.20
• CPC Class Codes: G01J 2003/1213 Filters in general, e.g. dichroic, band
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/0286 Constructional arrangements for compensating for fluctuations caused by temperature, humidity or pressure, or using cooling or temperature stabilization of parts of the device; Controlling the atmosphere inside a spectrometer, e.g. vacuum
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01J 5/024 Special manufacturing steps or sacrificial layers or layer structures
• CPC Class Codes: G01J 5/061 by controlling the temperature of the apparatus or parts thereof, e.g. using cooling means or thermostats
• CPC Class Codes: G01J 5/08 Optical arrangements
• CPC Class Codes: G01J 5/0802 Optical filters
• CPC Class Codes: G01J 5/0806 Focusing or collimating elements, e.g. lenses or concave mirrors
• CPC Class Codes: G01J 5/0808 Convex mirrors
• CPC Class Codes: G01J 5/602 using selective, monochromatic or bandpass filtering
• CPC Class Codes: G02B 17/0804 using two curved mirrors G02B17/0864, G02B17/0896 takes precedence
• CPC Class Codes: G02B 5/282 reflecting for infrared and transparent for visible light, e.g. heat reflectors, laser protection
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14649 Infrared imagers
• CPC Class Codes: H01L 31/02325 the optical elements not being integrated nor being directly associated with the device

Abstract

A sensor system senses a scene and includes a dual-band imaging infrared detector lying on a beam path, wherein the infrared detector detects infrared images in a first infrared wavelength band and in a second infrared wavelength band; and a two-color cold-shield filter lying on the beam path between the infrared detector and the scene. The cold-shield filter defines a first aperture size for infrared light of the first infrared wavelength band, and a second aperture size larger than the first aperture size for infrared light of the second infrared wavelength band. The first infrared wavelength band has wavelengths less than wavelengths of the second infrared wavelength band.

Claims

1. A sensor system for sensing a scene, the sensor system comprising:

a dual-band imaging detector lying on a beam path from the scene, wherein the detector detects images in a first wavelength band and in a second wavelength band; and

a two-color cold-shield filter lying on the beam path between the detector and the scene, wherein

a first filter portion of the cold-shield filter passes light of the first wavelength band and the second wavelength band, and

a second filter portion of the cold-shield filter does not pass light of the first wavelength band and passes light of the second wavelength band.

2. The sensor system of claim 1, wherein the first filter portion is a circle centered on the beam path, and the second filter portion is a circular annulus centered on the beam path.

3. The sensor system of claim 1, wherein the first filter portion is a circle centered on the beam path, and the second filter portion is a circular annulus centered on the beam path, and wherein an outer diameter of the circle is an inner diameter of the annulus.

4. The sensor system of claim 1, wherein the first wavelength band comprises wavelengths less than wavelengths of the second wavelength band.

5. The sensor system of claim 1, wherein the first wavelength band is from about 3 to about 5 micrometers wavelength, and the second wavelength band is from about 8 to about 12 micrometers wavelength.

6. The sensor system of claim 1, further including

a cooler housing enclosing the detector and the cold-shield filter, wherein the cooler housing includes a window to admit the beam path to an interior of the cooler housing.

7. The sensor system of claim 1, further including

a telescope and an imager lying on the beam path, wherein the telescope and the imager image the scene through the cold-shield filter and onto the detector.

8. The sensor system of claim 1, wherein the cold-shield filter comprises

a substrate having a first substrate portion corresponding to the first filter portion and a second substrate portion corresponding to the second filter portion,

a first multilayer bandpass coating overlying the first substrate portion, and

a second multilayer bandpass coating overlying the second substrate portion.

9. The sensor system of claim 1, wherein the cold-shield filter comprises

a substrate having a first substrate portion corresponding to the first filter portion and a second substrate portion corresponding to the second filter portion, and

a second multilayer bandpass coating overlying the second substrate portion.

10. The sensor system of claim 1, further including

an optical aberration corrector for the cold-shield filter, wherein the optical aberration corrector lies in the beam path.

11. A sensor system for sensing a scene, the sensor system comprising:

a dual-band imaging infrared detector lying on a beam path from the scene, wherein the infrared detector detects infrared images in a first infrared wavelength band and in a second infrared wavelength band;

a two-color cold-shield filter lying on the beam path between the infrared detector and the scene, wherein

a circular first filter portion of the cold-shield filter passes infrared light of the first infrared wavelength band and the second infrared wavelength band, wherein the first infrared wavelength band comprises wavelengths less than wavelengths of the second infrared wavelength band, and

an annular second filter portion of the cold-shield filter does not pass infrared light of the first infrared wavelength band and passes infrared light of the second infrared wavelength band, and wherein an outer diameter of the circle is an inner diameter of the annulus; and

a cooler housing enclosing the infrared detector and the cold-shield filter, wherein the cooler housing includes a window to admit the beam path to an interior of the cooler housing.

12. The sensor system of claim 11, wherein the first infrared wavelength band is from about 3 to about 5 micrometers wavelength, and the second infrared wavelength band is from about 8 to about 12 micrometers wavelength.

13. The sensor system of claim 11, further including

a telescope and an imager lying on the beam path, wherein the telescope and the imager image the scene onto the infrared detector.

14. The sensor system of claim 11, wherein the cold-shield filter comprises

a substrate having a first substrate portion corresponding to the first filter portion and a second substrate portion corresponding to the second filter portion, and

a second multilayer bandpass coating overlying the second substrate portion.

15. The sensor system of claim 11, wherein the cold-shield filter comprises

a substrate having a first substrate portion corresponding to the first filter portion and a second substrate portion corresponding to the second filter portion,

a first multilayer bandpass coating overlying the first substrate portion, and

a second multilayer bandpass coating overlying the second substrate portion.

16. The sensor system of claim 11, wherein the cold-shield filter has an optical aberration corrector affixed thereto overlying at least the second portion of the cold-shield filter.

17. A sensor system for sensing a scene, the sensor system comprising:

a dual-band imaging infrared detector lying on a beam path, wherein the infrared detector detects infrared images in a first infrared wavelength band and in a second infrared wavelength band; and

a two-color cold-shield filter lying on the beam path between the infrared detector and the scene, wherein the cold-shield filter defines

a first aperture size for infrared light of the first infrared wavelength band, and

a second aperture size larger than the first aperture size for infrared light of the second infrared wavelength band, wherein the first infrared wavelength band comprises wavelengths less than wavelengths of the second infrared wavelength band.

18. A sensor system for sensing a scene, the sensor system comprising:

a dual-band imaging infrared detector lying on a beam path from the scene, wherein the infrared detector detects infrared images in a first infrared wavelength band and in a second infrared wavelength band; and

a two-color cold-shield filter lying on the beam path between the infrared detector and the scene, wherein

a first filter portion of the cold-shield filter passes infrared light of the first infrared wavelength band and the second infrared wavelength band, and

a second filter portion of the cold-shield filter does not pass infrared light of the first infrared wavelength band and passes light of the second infrared wavelength band.

19. The sensor system of claim 18, wherein the cold-shield filter comprises

a substrate having a first substrate portion corresponding to the first filter portion and a second substrate portion corresponding to the second filter portion,

a first multilayer bandpass coating overlying the first substrate portion, and

a second multilayer bandpass coating overlying the second substrate portion.

20. The sensor system of claim 18, wherein the cold-shield filter comprises

a substrate having a first substrate portion corresponding to the first filter portion and a second substrate portion corresponding to the second filter portion, and

a second multilayer bandpass coating overlying the second substrate portion.