US3800906A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser heterodyne acoustic sensor
Assignee: United States Department of the Navy
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Filing: 1972-08-22
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Granted: 1974-04-02
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Expires: 1992-08-22
Abstract
Abstract First and second pairs of reflective elements including a single laser cell, define adjacent, parallel, resonant optical paths of different lengths through the same laser medium. One of the resonant optical paths is exposed to acoustic energy, changing its effective optical path length and the wavelength of the laser energy emitted by that path. Changes of the beat frequency between the two laser beams generated in the two resonant optical paths are detected and appropriately displayed as an indication of the intercepted acoustic energy.
Inventors
- 👤 D Albares
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:20
CPC Classifications
G; G02; G02F; G02F2/00; G02F2/002; G01; G01H; G01H9/00; H; H01; H01S; H01S3/00; H01S3/05; H01S3/08; H01S3/081; H01S3/082; H01S3/10; H01S3/102
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
135 words
A high sensitivity acoustic detector comprising: a single laser cell containing laser material; first and second pairs of reflective elements including said single laser cell therebetween and defining adjacent parallel resonant optical paths of different lengths traversing a common laser medium; a source of laser excitation energy disposed to energize said common laser medium for generating laser emission from said single laser cell, said laser emission being in two separate laser beams along said resonant optical paths of different lengths; means for exposing one of said resonant optical paths to acoustic energy for causing changes in its effective optical path length responsive to changes in the instantaneous amplitude of said acoustic energy; means for detecting changes of the beat frequency between said two laser beams; and means for indicating said changes of the beat frequency.
Claim 2
Dependent Claim
135 words
A high sensitivity acoustic detector comprising: a single laser cell containing laser material; first and second pairs of reflective elements including said single laser cell therebetween and defining adjacent parallel resonant optical paths of different lengths traversing a common laser medium; a source of laser excitation energy disposed to energize said common laser medium for generating laser emission from said single laser cell, said laser emission being in two separate laser beams along said resonant optical paths of different lengths; means for exposing one of said resonant optical paths to acoustic energy for causing changes in its effective optical path length responsive to changes in the instantaneous amplitude of said acoustic energy; means for detecting changes of the beat frequency between said two laser beams; and means for indicating said changes of the beat frequency.
Claim 3
Dependent Claim
25 words
A high sensitivity acoustic detector as claimed in claim 1 wherein said first and second pairs of reflective surfaces have one reflective element in common.
Claim 4
Dependent Claim
23 words
A high sensitivity acoustic detector as claimed in claim 1 wherein each of said pairs of reflective elements includes a partially reflective surface.
Claim 5
Dependent Claim
31 words
A high sensitivity acoustic detector as claimed in claim 1 wherein the optical path exposed to acoustic energy receives said energy substantially transversely to the major axis of said optical path.
Claim 6
Dependent Claim
30 words
A high sensitivity acoustic detector as claimed in claim 1 wherein the optical path exposed to acoustic energy receives said energy substantially along the major axis of said optical path.
Claim 7
Dependent Claim
25 words
A high sensitivity acoustic detecor as claimed in claim 5 wherein said acoustic energy displaces a reflective element of one of said resonant optical paths.
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) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |