US3742235A
Expired / Lapsed
US
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Bolometric detector utilizing electron paramagnetic resonance
Assignee: Advanced Technology Center Inc
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Filing: 1972-03-06
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Granted: 1973-06-26
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Expires: 1992-03-06
Abstract
Abstract Bolometric techniques are employed in conjunction with electron paramagnetic resonance to detect electromagnetic radiation. A crystal doped with a rare earth ion, iron group ion, or free radical, selectively absorbs a certain bandwidth of frequencies from the incoming radiation effectively converts this energy to a temperature rise in the host material by means of spin-lattice relaxation mechanisms. Attached in intimate thermal contact with the paramagnetic resonant material is a sensitive bolometer element that responds to this temperature rise. The temperature rise and associated bolometer signal, is an effective monitor of the presence of incoming radiation incident on the doped crystal or free radical material. To produce human readable intelligence concerning the incoming radiation incident on the resonant absorber, the bolometer element intimately contacting the crystal is also made part of a bridge circuit or other measuring means having an indicating meter or digital readout circuitry. The resonance absoprtion frequency may be tuned magnetically over a significantly wide range. Either waveguide feeds or optical focusing may be used to direct the incoming radiation energy to the area of the doped crystal or free radical crystal. Depending upon the nature of the resonant absorber, the absorption band may be made narrow or broad and positioned anywhere from a few GHz to several thousand GHz.
Inventors
- 👤 L Boatner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 23:43
CPC Classifications
G; G01; G01J; G01J5/00; G01J5/10; G01J5/20; G01R; G01R21/00
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
22 words
A passive bolometric radiation detector system as set forth in claim 1 including means for maintaining said material in a cryogenic environment.
Claim 2
Dependent Claim
41 words
A passive bolometric radiation detector system as set forth in claim 1 wherein said means for directing incoming radiation to said material includes an antenna, a waveguide feed and a resonant cavity to concentrate the magnetic field on said paramagnetic material.
Claim 3
Dependent Claim
35 words
A passive bolometric radiation detector system as set forth in claim 1 wherein said means for directing incoming radiation to said material includes a reflecting optical system for focusing incoming radiation on said paramagnetic material.
Claim 4
Dependent Claim
51 words
A passive bolometric radiation detector system as set forth in claim 1 wherein said means for generating a magnetic field includes means for varying the magnitude of the field to vary the Zeeman level separation and tune the response of said paramagnetic material to a selected frequency band of incoming radiation.
Claim 5
Dependent Claim
24 words
A passive bolometric radiation detector system as set forth in claim 1 wherein said material is a single crystal doped with a rare-earth ion.
Claim 6
Dependent Claim
19 words
A passive bolometric radiation detector system as set forth in claim 6 wherein the host crystal material is SrCl2.
Claim 7
Dependent Claim
20 words
A passive bolometric radiation detector system as set forth in claim 1 wherein said material is a free radical salt.
Claim 8
Dependent Claim
36 words
A passive bolometric radiation detector system as set forth in claim 1 wherein said crystal is doped at a level to establish a desired bandwidth of incoming radiation around the frequency established by the magnetic field.
Claim 9
Dependent Claim
21 words
A passive bolometric radiation detector system as set forth in claim 1 wherein said bolometer element is a gallium doped germanium.
Claim 10
Dependent Claim
124 words
A bolometric radiation detector system comprising: a paramagnetic impurity doped material having a relaxation mechanism for converting incoming radiation energy incident thereon into a rise in temperature thereof, means for generating a tunable magnetic field surrounding said paramagnetic material to split the Zeeman level of the paramagnetic ions of said material to separate the energy levels thereof to establish the frequency band at which resonant absorption occurs, means for directing incoming radiation to said material, a bolometer element in intimate thermal contact with said material and responsive to the temperature change thereof, circuit means connected to said bolometer element for generating a signal that varies with the temperature of said material, and means responsive to the generated signal to indicate the presence of radiation.
Claim 11
Dependent Claim
22 words
A bolometric radiation detector system as set forth in claim 11 including means for maintaining said paramagnetic material in a cryogenic environment.
Claim 12
Dependent Claim
39 words
A bolometric radiation detector system as set forth in claim 11 wherein said means for directing incoming radiation to said material includes an antenna, a waveguide feed and a resonant cavity to concentrate the magnetic field on said material.
Claim 13
Dependent Claim
34 words
A bolometric radiation detector system as set forth in claim 11 wherein said means for directing incoming radiation to said paramagnetic material includes a reflecting optical system for focusing incoming radiation on said material.
Claim 14
Dependent Claim
79 words
A bolometric radiation detector system as set forth in claim 11 wherein said means for generating said tunable magnetic field includes: an electromagnet to produce a magnetic field surrounding said material, a variable power supply connected to said electromagnet and having means for varying the current through said magnet for varying the magnitude of the magnetic field and thereby change the Zeeman level separation to tune the response of said material to a selected frequency band of incoming radiation.
Claim 15
Dependent Claim
36 words
A bolometric radiation detector system as set forth in claim 11 wherein said circuit means includes a bridge having said bolometer element in one arm thereof and a compensating bolometer element in the adjacent arm thereof.
Claim 16
Dependent Claim
77 words
A bolometric radiation detector system as set forth in claim 11 wherein said means for generating a tunable magnetic field includes: a permanent magnet to produce a magnetic field surrounding said material to establish the Zeeman level separation to tune the response of said material to a selected frequency band of incoming radiation, and tuning coils associated with said permanent magnet to fine tune the Zeeman level separation to further select the frequency band of incoming radiation.
Claim 17
Dependent Claim
19 words
A bolometric radiation detector system as set forth in claim 11 wherein said material is a free radical salt.
Claim 18
Dependent Claim
23 words
A bolometric radiation detector system as set forth in claim 11 wherein said material is a single crystal doped with a rare-earth ion.
Claim 19
Independent Claim
100 words
A method of detecting radiation, comprising the steps of: thermally contacting a bolometer element with a paramagnetic material having a relaxation mechanism for converting incoming radiation energy incident thereon into a rise in temperature of the element, generating a magnetic field surrounding said material to set the Zeeman level separation of the energy bands to establish the frequency band at which resonant absorption occurs in said wafer, directing incoming radiation to said wafer, and generating a signal that varies in accordance with the temperature change in the bolometer element to indicate the presence of radiation incident on the crystal wafer.
Claim 20
Dependent Claim
24 words
A method of detecting radiation as set forth in claim 20 including the step of maintaining the single crystal wafer in a cryogenic envirnoment.
Claim 21
Dependent Claim
44 words
A metohod of detecting radiation as set forth in claim 20 including the step of varying the magnitude of the magnetic field to vary the Zeeman level separation and tune the response of said crystal wafer to a selected frequency band of incoming radiation.
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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) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |