Patent US5298748A successfully refreshed from Google Patents.
US5298748A
Expired / Lapsed
US
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Uncooled tunneling infrared sensor
Assignee: California Institute of Technology
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Filing: 1992-06-15
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Granted: 1994-03-29
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Expires: 2012-06-15
Abstract
Abstract An uncooled infrared tunneling sensor in which the only moving part is a diaphragm which is deflected into contact with a micromachined silicon tip electrode prepared by a novel lithographic process. Similarly prepared deflection electrodes employ electrostatic force to control the deflection of a silicon nitride, flat diaphragm membrane. The diaphragm exhibits a high resonant frequency which reduces the sensor's sensitivity to vibration. A high bandwidth feedback circuit controls the tunneling current by adjusting the deflection voltage to maintain a constant deflection of the membrane which would otherwise change deflection depending upon incident infrared radiation. The resulting infrared sensor will meet or exceed the performance of all other broadband, uncooled, infrared sensors and can be miniaturized to pixel dimensions smaller than 100 μm. The technology is readily implemented as a small-format linear array suitable for commercial and spacecraft applications.
Inventors
- 👤 Thomas W. Kenny
- 👤 William J. Kaiser
- 👤 Judith A. Podosek
- 👤 Erika C. Vote
- 👤 Howard K. Rockstad
- 👤 Joseph K. Reynolds
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:42
CPC Classifications
G; G01; G01J; G01J5/00; G01J5/38; G01J5/42; G01J2005/425
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
102 words
An infrared sensor comprising: an enclosed chamber; a gas in said chamber; a metal closed flexible silicon nitride membrane forming a deflectable wall of said enclosed chamber; a metal coated silicon tip within tunneling distance of said membrane for establishing a tunneling current therebetween depending upon said distance; at least one electrode in spaced, opposing proximity to said membrane for electrostatically controlling the deflection of said membrane; and a feedback circuit connected to said tip for sensing said tunneling current and to said electrode for maintaining the deflection of said membrane irrespective of the level of infrared radiation incident upon said chamber.
Claim 2
Dependent Claim
102 words
An infrared sensor comprising: an enclosed chamber; a gas in said chamber; a metal closed flexible silicon nitride membrane forming a deflectable wall of said enclosed chamber; a metal coated silicon tip within tunneling distance of said membrane for establishing a tunneling current therebetween depending upon said distance; at least one electrode in spaced, opposing proximity to said membrane for electrostatically controlling the deflection of said membrane; and a feedback circuit connected to said tip for sensing said tunneling current and to said electrode for maintaining the deflection of said membrane irrespective of the level of infrared radiation incident upon said chamber.
Claim 3
Dependent Claim
14 words
The infrared sensor recited in claim 1 wherein said membrane is coated with gold.
Claim 4
Dependent Claim
14 words
The infrared sensor recited in claim 1 wherein said tip is coated with gold.
Claim 5
Dependent Claim
28 words
The infrared sensor recited in claim 1 wherein said membrane is coated with a layer of adhesion material, a layer of barrier material and a layer of metal.
Claim 6
Dependent Claim
13 words
The infrared sensor recited in claim 4 wherein said adhesion material is titanium.
Claim 7
Dependent Claim
13 words
The infrared sensor recited in claim 4 wherein said barrier material is platinum.
Claim 8
Dependent Claim
12 words
The infrared sensor recited in claim 4 wherein said metal is gold.
Claim 9
Dependent Claim
28 words
The infrared sensor recited in claim 1 wherein said tip is coated with a layer of adhesion material, a layer of barrier material and a layer of metal.
Claim 10
Dependent Claim
13 words
The infrared sensor recited in claim 8 wherein said adhesion material is titanium.
Claim 11
Dependent Claim
13 words
The infrared sensor recited in claim 8 wherein said barrier material is platinum.
Claim 12
Dependent Claim
12 words
The infrared sensor recited in claim 8 wherein said metal is gold.
Claim 13
Dependent Claim
12 words
The infrared sensor recited in claim 1 wherein said gas is air.
Claim 14
Dependent Claim
96 words
In a tunneling infrared sensor of the type having a gas-enclosing chamber, a deflectable membrane and an electrode tip for establishing a tunneling current dependent upon the deflection of said membrane in response to incident infrared radiation; the improvement comprising: at least one deflection electrode positioned in spaced relation to said membrane for electrostatically controlling the deflection of said membrane; and a feedback circuit connected between said tip and said electrode and responsive to said tunneling current for maintaining the deflection of said membrane within a selected range irrespective of the level of incident infrared radiation.
Claim 15
Dependent Claim
96 words
In a tunneling infrared sensor of the type having a gas-enclosing chamber, a deflectable membrane and an electrode tip for establishing a tunneling current dependent upon the deflection of said membrane in response to incident infrared radiation; the improvement comprising: at least one deflection electrode positioned in spaced relation to said membrane for electrostatically controlling the deflection of said membrane; and a feedback circuit connected between said tip and said electrode and responsive to said tunneling current for maintaining the deflection of said membrane within a selected range irrespective of the level of incident infrared radiation.
Claim 16
Dependent Claim
36 words
The improvement recited in claim 13 wherein said feedback circuit produces a voltage at said deflection electrode, the magnitude of said voltage being proportional to the difference between said tunneling current and a preset reference current.
Claim 17
Dependent Claim
18 words
The improvement recited in claim 14 wherein said feedback circuit has a bandwidth of at least 50 kHz.
Claim 18
Dependent Claim
20 words
The improvement recited in claim 13 wherein said membrane has a mechanical resonance frequency which is at least 10 kHz.
Claim 19
Dependent Claim
72 words
An infrared sensor of the type having a gas-enclosing chamber responsive to incident infrared radiation and comprising: a tunneling transducer configured for generating a tunneling current dependent upon the level of incident infrared radiation; said tunneling transducer having a tunneling tip and a deflection membrane; and electrostatically controlled deflection means responsive to said tunneling current for retaining the deflection of said membrane substantially constant irrespective of said level of said infrared radiation.
Claim 20
Dependent Claim
72 words
An infrared sensor of the type having a gas-enclosing chamber responsive to incident infrared radiation and comprising: a tunneling transducer configured for generating a tunneling current dependent upon the level of incident infrared radiation; said tunneling transducer having a tunneling tip and a deflection membrane; and electrostatically controlled deflection means responsive to said tunneling current for retaining the deflection of said membrane substantially constant irrespective of said level of said infrared radiation.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-03-28 | 1997-09-27 | 1998-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-28 | 2001-09-27 | 2002-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-28 | 2005-09-27 | 2006-03-29 | $7700.00 | Window Closed / Lapsed |