US3820037A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser control system
Assignee: Lockheed Martin Corp
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Filing: 1972-09-25
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Granted: 1974-06-25
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Expires: 1992-09-25
Abstract
Abstract A laser beam provided by a laser oscillator is transmitted along a path so as to be intercepted and amplified by a laser amplifier. A portion of the laser beam may be reflected as a feedback signal to the oscillator and cause oscillator pulling. To prevent such unwanted feedback, an acousto-optical isolator is interposed between the amplifier and the oscillator which causes the laser beam to be frequency shifted each time it passes through the isolator. The frequency shift is sufficient that the laser beam feedback signal arrives at the oscillator shifted in frequency by an amount to minimize oscillator pulling.
Inventors
- 👤 V Corcoran
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 07:49
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/23; H01S3/2308; H01S3/2366
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
184 words
A laser beam control system comprising: laser oscillator means generating a laser beam at a frequency F falling within a desired gain transition band extending from frequency F1 to frequency F2; laser amplifier means for receiving and amplifying said laser beam while reflecting at least a portion of said beam back toward said oscillator means; acousto-optic modulating means interposed between said oscillator means and said amplifying means for intercepting transmitted and reflected laser beams, and including means for acoustically exciting said modulating means to generate an acoustic signal and consequently an acoustic wave at a modulating frequency FM along a direction extending substantially transverse to the paths of said transmitted and reflected laser beams so that both the transmitted and reflected laser beams are frequency modulated by said modulating frequency FM, said modulating frequency FM being on the order of at least one-half (F1 - F2) so that said feedback laser beam exhibits a frequency which is substantially at or outside of the end points of said frequency band so as to not effectively interact with and degrade the output of said oscillator means.
Claim 2
Dependent Claim
184 words
A laser beam control system comprising: laser oscillator means generating a laser beam at a frequency F falling within a desired gain transition band extending from frequency F1 to frequency F2; laser amplifier means for receiving and amplifying said laser beam while reflecting at least a portion of said beam back toward said oscillator means; acousto-optic modulating means interposed between said oscillator means and said amplifying means for intercepting transmitted and reflected laser beams, and including means for acoustically exciting said modulating means to generate an acoustic signal and consequently an acoustic wave at a modulating frequency FM along a direction extending substantially transverse to the paths of said transmitted and reflected laser beams so that both the transmitted and reflected laser beams are frequency modulated by said modulating frequency FM, said modulating frequency FM being on the order of at least one-half (F1 - F2) so that said feedback laser beam exhibits a frequency which is substantially at or outside of the end points of said frequency band so as to not effectively interact with and degrade the output of said oscillator means.
Claim 3
Dependent Claim
176 words
A laser beam control system comprising: laser oscillator means generating a laser beam at a frequency F falling within a desired gain transition extending from frequency F1 to frequency F2; laser amplifier means for receiving and amplifying said laser beam while reflecting at least a portion of said beam back toward said oscillator means; acousto-optic modulating means interposed between said oscillator means and said amplifying means for interceptng transmitted and reflected laser beams, and including means for acoustically exciting said modulating means to generate an acoustic signal and consequently an acoustic wave at a modulating frequency FM along a direction extending substantially transverse to the paths of said transmitted and reflected laser beams so that both the transmitted and reflected laser beams are frequency shifted by said modulating frequency FM, said modulating frequency FM being greater than one-half the difference between frequencies F1 and F2 so that the twice modulated feed-back laser beAm exhibits a frequency outside of the desired frequency band to thereby minimize frequency pulling of said oscillator means by said feedback laser beam.
Claim 4
Dependent Claim
176 words
A laser beam control system comprising: laser oscillator means generating a laser beam at a frequency F falling within a desired gain transition extending from frequency F1 to frequency F2; laser amplifier means for receiving and amplifying said laser beam while reflecting at least a portion of said beam back toward said oscillator means; acousto-optic modulating means interposed between said oscillator means and said amplifying means for interceptng transmitted and reflected laser beams, and including means for acoustically exciting said modulating means to generate an acoustic signal and consequently an acoustic wave at a modulating frequency FM along a direction extending substantially transverse to the paths of said transmitted and reflected laser beams so that both the transmitted and reflected laser beams are frequency shifted by said modulating frequency FM, said modulating frequency FM being greater than one-half the difference between frequencies F1 and F2 so that the twice modulated feed-back laser beAm exhibits a frequency outside of the desired frequency band to thereby minimize frequency pulling of said oscillator means by said feedback laser beam.
Claim 5
Dependent Claim
136 words
A laser beam control system comprising: laser oscillator means for generating a laser beam at a frequency F and including a resonant cavity defined between a pair of end reflectors of which one is a partial reflector for transmitting said beam in a forward direction from said oscillator means, laser amplifier means positioned to receive said transmitted laser beam and including means for reflecting a portion of said laser beam as a feedback signal toward said partial reflector, and modulating frequency generating means for shifting both the transmitted and reflected laser beams by an amount equal to at least the bandwidth of the gain transition at the frequency F, so that the frequency shifted feedback signal will not effectively interact with the radiation emitted from the oscillator means to cause frequency pulling of said oscillator means.
Claim 6
Dependent Claim
136 words
A laser beam control system comprising: laser oscillator means for generating a laser beam at a frequency F and including a resonant cavity defined between a pair of end reflectors of which one is a partial reflector for transmitting said beam in a forward direction from said oscillator means, laser amplifier means positioned to receive said transmitted laser beam and including means for reflecting a portion of said laser beam as a feedback signal toward said partial reflector, and modulating frequency generating means for shifting both the transmitted and reflected laser beams by an amount equal to at least the bandwidth of the gain transition at the frequency F, so that the frequency shifted feedback signal will not effectively interact with the radiation emitted from the oscillator means to cause frequency pulling of said oscillator means.
Claim 7
Dependent Claim
83 words
A laser control system as set forth in claim 3, wherein said frequency shifting means includes acousto-optic modulator means positioned to intercept said feedback signal and means for generating an acoustic signal and consequently an acoustic wave traveling along a path transverse to said laser feedback signal at a modulating frequency FM so that the laser feedback signal is frequency shifted feedback signal will not effectively interact with the radiation emitted from the oscillator means to cause frequency pulling of said oscillator means.
Claim 8
Dependent Claim
85 words
A laser control system as set forth in claim 4, wherein said modulator means is interposed in the optical path between said oscillator means and said amplifier means such that said laser beam is shifted in frequency by said modulating frequency FM each time it passes through said modulator means so that the feedback signal to said oscillator means is shifted by a frequency equal to twice that of said modulating frequency so as to be outside of the gain transition of said oscillator means.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |