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US4933555A
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Thermal imager
Assignee: Leonardo UK Ltd
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Filing: 1988-02-03
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Granted: 1990-06-12
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Expires: 2008-02-03
Abstract
Abstract A thermal imager including a cryogenically cooled detector element array and a scanning element has an optical system with a field of view limited by a field stop (2). A retroreflective region (6) is provided on part of the field stop to act as a temperature reference by allowing the detector array to "look at" itself. A second, different temperature reference (5) is provided on another part of the field stop and the two references are used to equalize and adjust the output characteristics of the elements in the detector array.
Inventors
- 👤 Brian F. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 01:01
CPC Classifications
G; G01; G01J; G01J5/00; G01J5/02; G01J5/06; G01J5/061; G01J5/08; G01J5/0806; G01J5/0831; G01J5/52; G01J5/53; H; H04; H04N; H04N23/00; H04N23/20; H04N23/23; H04N25/00; H04N25/60; H04N25/67; H04N25/671; H04N25/672; G01J2005/0077; G01J2005/526; G01J2005/528; G01J5/80
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
141 words
A thermal imager including: a thermal sensor and a first temperature reference means including retro-reflective means for providing a retro-reflected image of the sensor for use as a first temperature reference, a second temperature reference means, said second temperature reference means including means for providing a second temperature reference at a different temperature from that of the retro-reflected image, an optical system for admitting electromagnetic radiation to the thermal sensor, the optical system including a field stop adapted to limit the field of view of the scene viewed by the sensor, and wherein said first and second temperature reference means are situated on portions of the field stop; scanning means adapted to scan over the field of view of the scene and, when required, also over each temperature reference means; and electrical means for processing an output of the thermal sensor.
Claim 2
Dependent Claim
141 words
A thermal imager including: a thermal sensor and a first temperature reference means including retro-reflective means for providing a retro-reflected image of the sensor for use as a first temperature reference, a second temperature reference means, said second temperature reference means including means for providing a second temperature reference at a different temperature from that of the retro-reflected image, an optical system for admitting electromagnetic radiation to the thermal sensor, the optical system including a field stop adapted to limit the field of view of the scene viewed by the sensor, and wherein said first and second temperature reference means are situated on portions of the field stop; scanning means adapted to scan over the field of view of the scene and, when required, also over each temperature reference means; and electrical means for processing an output of the thermal sensor.
Claim 3
Dependent Claim
18 words
A thermal imager as claimed in claim 1 wherein the second temperature reference means comprises a Peltier cell.
Claim 4
Dependent Claim
71 words
A thermal imager as claimed in claim 4 wherein the imager is a scanning type imager including one or more scanning elements adapted to scan over a field of view greater than that of the scene to be imaged and wherein the retro-reflective means is situated outside the field of view of the scene but within the possible field of view which may be scanned by scanning elements of the imager.
Claim 5
Dependent Claim
123 words
A thermal imager comprising: a thermal sensor; an optical system for admitting electro-magnetic radiation to the thermal sensor, a field stop positioned to limit a field of view of a scene viewed by said thermal sensor, a first temperature reference region including retro-reflective means for providing a retro-reflected image of the sensor as a first temperature reference, a second temperature reference region including means for providing a second temperature reference at a known temperature different from the temperature of the retro-reflected image; scanning means arranged to scan over the field of view of the scene and, when required, also over both temperature reference regions so as to provide two different temperature references; and electrical means for processing an output of the thermal sensor.
Claim 6
Dependent Claim
123 words
A thermal imager comprising: a thermal sensor; an optical system for admitting electro-magnetic radiation to the thermal sensor, a field stop positioned to limit a field of view of a scene viewed by said thermal sensor, a first temperature reference region including retro-reflective means for providing a retro-reflected image of the sensor as a first temperature reference, a second temperature reference region including means for providing a second temperature reference at a known temperature different from the temperature of the retro-reflected image; scanning means arranged to scan over the field of view of the scene and, when required, also over both temperature reference regions so as to provide two different temperature references; and electrical means for processing an output of the thermal sensor.
Claim 7
Dependent Claim
19 words
A thermal imager as claimed in claim 4 wherein the thermal sensor comprises an array of thermal detector elements.
Claim 8
Dependent Claim
30 words
A thermal imager as claimed in claim 5 adapted to be scanned in swathes and wherein at least one of the swathes may be extended to scan each reference region.
Claim 9
Dependent Claim
28 words
A thermal imager as claimed in claim 6 wherein the first and second temperature reference regions are situated at the beginning and end of one swathe line only.
Claim 10
Dependent Claim
18 words
A thermal imager as claimed in claim 4 wherein the retro-reflective means comprises at least one corner cube.
Claim 11
Dependent Claim
28 words
A thermal imager as claimed in claim 4 including filtering means on the retro-reflective means for raising the perceived temperature of the retro-reflected image by a predetermined amount.
Claim 12
Dependent Claim
16 words
A thermal imager as claimed in claim 9 wherein the filtering means is a multi-layer coating.
Claim 13
Dependent Claim
25 words
A thermal imager as recited in claim 4 wherein said first and second temperature reference regions are situated on respective portions of the field stop.
Claim 14
Dependent Claim
22 words
A thermal imager as recited in claim 11 wherein said second temperature reference region comprises an untreated clamp region at ambient temperature.
Claim 15
Dependent Claim
22 words
A thermal imager as recited in claim 4 wherein said second temperature reference region comprises an untreated clamp region at ambient temperature.
Claim 16
Dependent Claim
40 words
A thermal imager as recited in claim 4 wherein said imager is scanned in swathes, and wherein at least one of said means providing said first and second temperature references has a width substantially equal to one of said swaths.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-11 | 1993-12-11 | 1994-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-11 | 1997-12-11 | 1998-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-11 | 2001-12-11 | 2002-06-12 | $7700.00 | Window Closed / Lapsed |