US4491867A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for the heterodyne detection of an optical image
Assignee: Thales SA
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Filing: 1982-09-23
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Granted: 1985-01-01
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Expires: 2002-09-23
Abstract
Abstract A device for the heterodyne detection of the image of targets illuminated by a laser, wherein the target reflects a wave Σ 1 , which is amplified in an included refractive index variation medium also illuminated by a reference wave Σ R derived from the laser to produce an amplified wave Σ 2 . A portion of the wave Σ 1 prior to amplification is directed incident on a frequency shifter to produce frequency shifted wavefront Σ 10 . Wavefront Σ 2 and the frequency-shifted wavefront Σ 10 are directed incident on the same partially reflection mirror to interfere with one another and the resultant beat interference wave is focused on a matrix of photodetectors and then filtered. This device has application to infrared image detection.
Inventors
- 👤 Jean-Pierre Huignard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 00:40
CPC Classifications
G; G03; G03H; G03H1/00; G01; G01J; G01J9/00; G01J9/04; G02; G02F; G02F1/00; G02F1/01; G02F1/03; G02F1/0338
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
183 words
A heterodyne detection device for the heterodyne detection of an optical image reflected off a target illuminated by beams emitted from a laser, comprising: an induced refractive index variation medium (C) adapted to be illuminated by a first portion of a wavefront Σ 1 reflected by said target and a portion of a plane wavefront obtained from the beams emitted by said laser, wherein said wavefront Σ 1 is amplified in said medium (C) into an amplified wavefront Σ 2 ; means for frequency shifting a second portion of said wavefront Σ 1 to produce a frequency shift wavefront Σ 10 ; a matrix of photodetectors; interference means having incident thereon said wavefront Σ 2 and said wavefront Σ 10 for producing heterodyne signals at a beat frequency between the frequencies of said wavefronts Σ 1 and Σ 10 and for focusing said heterodyne signals on said matrix of photodetectors for detection thereby, said matrix of photodetectors producing detected heterodyne signals; and filter means coupled to said matrix of photodetectors for filtering said detected heterodyne signals in a band including said beat frequency.
Claim 2
Dependent Claim
183 words
A heterodyne detection device for the heterodyne detection of an optical image reflected off a target illuminated by beams emitted from a laser, comprising: an induced refractive index variation medium (C) adapted to be illuminated by a first portion of a wavefront Σ 1 reflected by said target and a portion of a plane wavefront obtained from the beams emitted by said laser, wherein said wavefront Σ 1 is amplified in said medium (C) into an amplified wavefront Σ 2 ; means for frequency shifting a second portion of said wavefront Σ 1 to produce a frequency shift wavefront Σ 10 ; a matrix of photodetectors; interference means having incident thereon said wavefront Σ 2 and said wavefront Σ 10 for producing heterodyne signals at a beat frequency between the frequencies of said wavefronts Σ 1 and Σ 10 and for focusing said heterodyne signals on said matrix of photodetectors for detection thereby, said matrix of photodetectors producing detected heterodyne signals; and filter means coupled to said matrix of photodetectors for filtering said detected heterodyne signals in a band including said beat frequency.
Claim 3
Dependent Claim
98 words
A heterodyne detection device according to claim 1, comprising: a first partially reflecting mirror for separating said wavefront Σ 1 into said first and second portions, wherein said first portion is directed incident on said medium (C) and said second portion is directed incident on said frequency shifting means; said interference means comprising a second partially reflecting mirror having incident thereon said wavefronts Σ 2 and Σ 10 for producing an interference wavefront based on interference between said wavefronts Σ 2 and Σ 10 , and a lens for focusing said interference wavefront on said matrix of photodetectors.
Claim 4
Dependent Claim
29 words
A heterodyne detection device according to claim 2, wherein said frequency shifting means comprises: a mirror mounted on a piezoelectric device to which is applied a periodic sawtooth voltage.
Claim 5
Dependent Claim
17 words
A heterodyne detection device according to claim 2, wherein said frequency shifting means comprises: an acoustic reflector.
Claim 6
Dependent Claim
18 words
A heterodyne detection device according to claim 1, wherein the induced refractive index variation medium (C) is photorefractive.
Claim 7
Dependent Claim
21 words
A heterodyne detection device according to claim 1, wherein the induced refraction index variation medium (C) utilizes the optical Kerr effect.
Claim 8
Dependent Claim
25 words
A heterodyne detection device according to claim 1, wherein the induced refractive index variation medium comprises a gas being in a state of saturated absorption.
Claim 9
Dependent Claim
20 words
A heterodyne detection device according to claim 1, wherein the induced refractive index variation medium (C) comprises a semiconductor medium.
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) | 1988-01-01 | 1988-07-02 | 1989-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-01 | 1992-07-02 | 1993-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-01 | 1996-07-02 | 1997-01-01 | $7700.00 | Window Closed / Lapsed |