Focal plane filtered multispectral multidetector imager

• US 5,568,186 A
• Filed: 12/27/1994
• Issued: 10/22/1996
• Est. Priority Date: 11/15/1993
• Status: Expired due to Fees

• Current Assignee: The United States Of America As Represented By The Secretary Of The Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Althouse, Mark L. G.
• Primary Examiner(s): Peng, John K.
• Assistant Examiner(s): GRANT, CHRISTOPHER C
• Application Number:
  US08/365,374
• Time in Patent Office: 665 Days
• Field of Search: 348/164, 348/25, 348/32, 348/33, 250/339.02, 250/339.12, 250/339.13, 250/347, 250/352, 250/332, 356/320, 356/437, 340/632, 340/634
• US Class Current: 348/33
• CPC Class Codes: G01J 3/06 Scanning arrangements arrangements for order-selection
• CPC Class Codes: G01J 3/14 using refracting elements, e.g. prisms G01J3/18, G01J3/26 take precedence prisms per se G02B5/04
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G02B 26/0883 the refracting element being a prism
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths
• CPC Class Codes: H04N 23/23 from thermal infrared radiation
• 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

A dewar cooled piezo electric activated beam splitter permits a filtered dimensional multispectral multidetector staring imager to operate as a target acquisition and recognition device as well as a detector and classifier of unknown chemical vapors or other targets with spectral fingerprint.

Claims

1. A filtered multispectral multidetector imager, which comprises:

(a) first prism means providing a first optical path for radiation therethrough;

(b) second prism means proximately positioned adjacent to said first prism means for providing a second optical path for radiation therethrough, said first prism means and said second prism means having an air gap therebetween;

(c) piezo electric transducer means operatively connected to said first prism means for reciprocally opening and closing said air gap intermediate said first and second prism means and thereby switching between said first optical path and said second optical path;

(d) first array detector means in alignment with said first prism means for detecting radiation passing through said first prism means;

(f) first substrate means for supporting said first array detector means;

(g) second array detector means for detecting radiation reflected by said second prism means;

(h) second substrate means for supporting said second array detector means, said second substrate means having a front and a rear surface; and

(i) spectral filter array means operatively supported on said second substrate means intermediate said second prism means and said second detector means for providing a plurality of band pass filters for generation of a single frame multispectral image.

2. The multispectral multidetector imager of claim 1, further comprising:

(a) enclosure means having an interior chamber, said enclosure means providing protection from stray ambient radiation and having aperture means so that a field of radiation can pass therethrough; and

(b) wherein said first array detector means, said first substrate means, said second array detector means, and said second substrate means are disposed within said interior chamber of said enclosure means so that they are only exposed to the field of radiation passing through said aperture means.

3. The multispectral multidetector imager of claim 2, wherein said first prism means, said second prism means, and said piezo electric transducer means are also disposed within said interior chamber of said enclosure means.

4. The multispectral multidetector imager of claim 3, wherein said enclosure means comprises dewar means for maintaining said imager at cryogenic temperatures.

5. A multispectral multidetector imager as recited in claim 4, wherein said aperture means includes a lens positioned in front of said aperture for positioning of said first and second prism means at an intermediate focus position.

6. A multispectral multidetector imager as recited in claim 5, wherein said aperture means includes an optical window for positioning said first and second prism means at the focal plane of said optical window.

7. A multispectral multidetector imager as recited in claim 6, wherein said second array detector means includes

a plurality of band pass detector elements deposited on the front surface of said detector substrate.

8. A multispectral multidetector imager as recited in claim 7 wherein said first array detector means includes:

a transparent detector substrate having a front surface and a rear surface;

a plurality of optical band pass filters deposited on said rear surface of said detector substrate;

a detector array having a plurality of detector elements operatively on said front surface of said transparent substrate for purpose of rear illumination; and

a plurality of doped channel elements intermediate said detector elements.

9. A multispectral multidetector imager as recited in claim 8 wherein said two dimensional spectral filter array means includes a plurality of spectral band pass filters positioned as a staring imager with no scanning of the field of view required to form an image.

10. A multispectral multidetector imager as recited in claim 9 wherein said plurality of band pass spectral filter array means includes a plurality of spectral filter patches position in a pattern wherein every pass band patch has three or more pass bands adjacent to it and no filter patches of the same pass band are adjacent.

11. A multispectral multidetector imager as recited in claim 10, wherein each of said detector elements has a corresponding individual filter pass band patch.

12. The multispectral multidetector imager of claim 11, wherein said filter patches divide the 8-12 micron wavelength band fully into 1/2 micron wide segments.

13. A multispectral multidetector imager as recited in claim 3 wherein said first and second prism means each include a diagonal face oppositely positioned having a surface roughness of λ

/20 or better; and

a diagonal air gap between said first and second diagonal faces of λ

/5 or smaller.

14. A filtered multispectral detector imager, which comprises:

(a) a transparent detector substrate having a front surface and a rear surface;

(b) a plurality of optical band pass filters deposited on said rear surface of said substrate;

(c) a detector array having a plurality of band pass detector elements operatively on said front surface of said transparent substrate for purposes of rear illumination;

(d) a plurality of doped channel elements intermediate said detector elements;

(e) dewar means having an interior chamber, said dewar means maintaining said imager at cryogenic temperatures and providing protection from stray radiation and having aperture means so that a field of radiation can pass therethrough; and

(f) wherein said transparent substrate, said filters, said detector array, and said doped channel elements are disposed within said interior chamber of said dewar means so that only radiation passing through said aperture means is detected.

15. The multispectral detector imager of claim 14, wherein said two dimensional spectral filter array means includes a plurality of spectral band pass filters positioned as a staring imager with no scanning of the field of view required to form an image.

16. The multispectral detector imager of claim 15, wherein said plurality of band pass spectral filter array means includes a plurality of spectral filter patches positioned in a pattern wherein every pass band patch has three or more pass bands adjacent to it and no filter patches of the same pass band are adjacent.

17. The multispectral detector imager of claim 16, wherein each of said detector elements has a corresponding individual filter pass band patch.

18. The multispectral detector imager of claim 17, wherein said filter patches divide the 8-12 micron wavelength band fully into 1/2 micron wide segments.