US4422762A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ring laser
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1981-08-17
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Granted: 1983-12-27
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Expires: 2001-08-17
Abstract
Abstract A dithered ring laser particularly adapted for use as a gyro wherein backscatter from the mirrors is minimized by servoing the mirror inward and outward positions so that the sum of the AM amplitudes of the envelopes of the counterpropagating waves is reduced to a minimum value, then further servoing the mirrors to reduce the difference between such AM amplitudes.
Inventors
- 👤 Thomas J. Hutchings
- 👤 Gary D. Babcock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:53
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/05; H01S3/08; H01S3/081; H01S3/083; G; G01; G01C; G01C19/00; G01C19/58; G01C19/64; G01C19/66; G01C19/661; G01C19/665
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
153 words
In combination: a ring laser, including a plurality of corner mirrors defining a ring laser path, transducers to control the inward and outward position of said mirrors, apparatus for detecting the AC amplitudes of the envelopes of two frequency modulated laser traveling waves counterpropagating along said laser path, apparatus for differentially dithering the laser path length, servo means for controlling the position of at least one said transducer and mirror to control and tune the length of the path of said laser; apparatus connected to said detecting apparatus for producing two signals which are measures of the AC amplitudes of the envelopes of said counterpropagating waves; summing means connected to receive said AC amplitude signals and to produce a sum signal which is a measure of the sum of said AC amplitude signals; and means for servoing the position of at least one of said transducers and mirrors to minimize said sum signal.
Claim 2
Dependent Claim
153 words
In combination: a ring laser, including a plurality of corner mirrors defining a ring laser path, transducers to control the inward and outward position of said mirrors, apparatus for detecting the AC amplitudes of the envelopes of two frequency modulated laser traveling waves counterpropagating along said laser path, apparatus for differentially dithering the laser path length, servo means for controlling the position of at least one said transducer and mirror to control and tune the length of the path of said laser; apparatus connected to said detecting apparatus for producing two signals which are measures of the AC amplitudes of the envelopes of said counterpropagating waves; summing means connected to receive said AC amplitude signals and to produce a sum signal which is a measure of the sum of said AC amplitude signals; and means for servoing the position of at least one of said transducers and mirrors to minimize said sum signal.
Claim 3
Dependent Claim
27 words
Apparatus as recited in claim 1 and further comprising servo control transfer means for transferring controlling signals in sequence from one said mirror to another said mirror.
Claim 4
Dependent Claim
46 words
Apparatus as recited in claim 1 and further comprising means for sensing the end of travel of said transducers; and means for incrementing the positions of said transducers and mirrors to cause the perimeter to shift by substantially an integral number of wavelengths of laser light.
Claim 5
Dependent Claim
14 words
Apparatus as recited in claim 1 in which said servo means are digital servos.
Claim 6
Dependent Claim
22 words
Apparatus as recited in claim 2 in which said servo means are digital servos, and said transferring means comprises a digital processor.
Claim 7
Dependent Claim
23 words
Apparatus as recited in claim 3 in which said servo means are digital servos, and said means for incrementing comprises a digital processor.
Claim 8
Dependent Claim
88 words
Apparatus as recited in claim 1 and further comprising: apparatus for subtracting said two AC amplitude signals to produce a difference signal which is a measure of the absolute amplitude of the difference between said subtracted signals; servo control transfer means, including means for sensing when said sum signal is minimized, for transferring control of the position of said controlled transducers and mirrors from said sum signal to said difference signal; and means for limiting the travel of said transducers and mirrors under control of said difference signal.
Claim 9
Dependent Claim
27 words
Apparatus as recited in claim 7 and further comprising servo control transfer means for transferring controlling signals in sequence from one said mirror to another said mirror.
Claim 10
Dependent Claim
40 words
Apparatus as recited in claim 7 and further comprising means for sensing the end of travel of said transducers, and means for incrementing the position of said transducers and mirrors by substantially an integral number of wavelengths of laser light.
Claim 11
Dependent Claim
22 words
Apparatus as recited in claim 7 in which said servo means are digital servos, and said transferring means comprises a digital processor.
Claim 12
Dependent Claim
22 words
Apparatus as recited in claim 8 in which said servo means are digital servos, and said transferring means comprises a digital processor.
Claim 13
Dependent Claim
22 words
Apparatus as recited in claim 9 in which said servo means are digital servos, and said transferring means comprises a digital processor.
Claim 14
Dependent Claim
47 words
Apparatus as recited in claim 7 and further comprising servo control transfer means, including means for sensing the travel of said controlled mirrors in response to said difference signal, for transferring control of the position of said controlled mirrors from said difference signal to said sum signal.
Claim 15
Dependent Claim
27 words
Apparatus as recited in claim 13 and further comprising servo control transfer means for transferring controlling signals in sequence from one said mirror to another said mirror.
Claim 16
Dependent Claim
46 words
Apparatus as recited in claim 13 and further comprising means for sensing the end of travel of said transducers, and means for incrementing the positions of said transducers and mirrors to cause the perimeter to change by substantially an integral number of wavelengths of laser light.
Claim 17
Dependent Claim
22 words
Apparatus as recited in claim 13 in which said servo means are digital servos, and said transferring means comprises a digital processor.
Claim 18
Dependent Claim
22 words
Apparatus as recited in claim 14 in which said servo means are digital servos, and said transferring means comprises a digital processor.
Claim 19
Dependent Claim
22 words
Apparatus as recited in claim 15 in which said servo means are digital servos, and said incrementing means comprises a digital processor.
Claim 20
Dependent Claim
41 words
Apparatus as recited in one of claims 5, 6, 10, 11, 12, 16 or 17 in which said digital processor further switches control of the laser path length away from one mirror transducer being controlled for backscatter correction to another mirror.
Claim 21
Independent Claim
80 words
A method for reducing backscattering in dithered ring lasers having adjustable corner mirrors and transducers for positioning said mirrors, and having means for producing electrical signals which are measures of the low frequency AC component of the envelope of counterpropagating frequency modulated laser waves comprising; measuring the amplitudes of said electrical signals; additively combining said amplitudes; and adjusting the position of at least one of said transducers and mirrors to minimize the amplitude of the sum of said combined amplitudes.
Claim 22
Independent Claim
80 words
A method for reducing backscattering in dithered ring lasers having adjustable corner mirrors and transducers for positioning said mirrors, and having means for producing electrical signals which are measures of the low frequency AC component of the envelope of counterpropagating frequency modulated laser waves comprising; measuring the amplitudes of said electrical signals; additively combining said amplitudes; and adjusting the position of at least one of said transducers and mirrors to minimize the amplitude of the sum of said combined amplitudes.
Claim 23
Dependent Claim
45 words
A method as recited in claim 20 and further comprising: subtractively combining the amplitudes of said electrical signals; adjusting the position of at least one of said transducers and mirrors to reduce the absolute value of the difference between said last named subtractively combined signals
Claim 24
Dependent Claim
35 words
A method as recited in claim 21 in which said mirrors are consecutively adjusted through a predetermined limited range of movement to reduce the amplitude of the difference between said last named subtractively combined signals.
Claim 25
Dependent Claim
26 words
A method as recited in claim 20 in which said mirrors are consecutively adjusted to minimize the amplitude of the sum of said additively combined signal.
Claim 26
Dependent Claim
44 words
A method as recited in claim 23 and further comprising: subtractively combining the amplitudes of said electrical signals; and adjusting the position of at least one of said mirrors to reduce the absolute value of the difference between said last named subtractively combined signals.
Claim 27
Dependent Claim
36 words
A method as recited in claim 24 in which said mirrors are consecutively adjusted through a predetermined limited range of movement to reduce the absolute value of the difference between said last named subtractively combined values.
References Cited (Backward Citations)
US3597088A
Cited
US4152071A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-12-26 | 1987-06-27 | 1987-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-26 | 1991-06-27 | 1991-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-26 | 1995-06-27 | 1995-12-27 | $7700.00 | Window Closed / Lapsed |