Patent US3786681A successfully refreshed from Google Patents.
US3786681A
Expired / Lapsed
US
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Electromagnetic wave modulation and measurement system and method
Assignee: Sanmina Corp
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Filing: 1971-03-04
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Granted: 1974-01-22
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Expires: 1991-03-04
Abstract
Abstract Electromagnetic waves with multiple polarization and/or propagation direction modes, preferably in the form of laser waves, are modulated by means of force-responsive devices such as amorphous quartz elements. The application of force or acceleration to the modulator creates a difference in frequency of two of the modes. That frequency difference is a function of the force or acceleration being measured. The two signals are combined and their difference is detected in a beat detector. In a preferred embodiment, the electromagnetic waves are developed in a ring laser operating with plural circular polarization modes. Preferably, each polarization mode exists in one of the counter-directional laser beams. The modulator is a quartz cylinder located in the laser cavity. The force is applied in the form of a torque tending to twist the cylinder about its longitudinal axis. The device provides a high degree of sensitivity and a wide range in the measurement of force and acceleration. The invention is described as it is used in gravimeters, pressure altimeters and pressure measurement devices.
Inventors
- 👤 R Kiehn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 19:38
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/10; H01S3/106; G; G01; G01L; G01L1/00; G01L1/24; G01L1/242; G01L1/243; G01L11/00; G01L11/02; G01L11/025; G01L9/00; G01L9/0033; G01L9/0039; G01P; G01P15/00; G01P15/02; G01P15/08; G01V; G01V7/00; G01V7/08; G01V7/10; H01S3/05; H01S3/08; H01S3/081; H01S3/083
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
86 words
A force-responsive measurement device comprising, in combination, laser beam generator means for generating a beam of electromagnetic waves having a plurality of circular polarization modes, modulator means comprising a photo-elastic element for differentially alternating the characteristics of said polarization modes in response to the application of a stress, means for applying a torque proportional to said force to said element and stressing said element about the axis of the laser beam to produce a frequency difference between said modes, and means for detecting said frequency difference.
Claim 2
Dependent Claim
86 words
A force-responsive measurement device comprising, in combination, laser beam generator means for generating a beam of electromagnetic waves having a plurality of circular polarization modes, modulator means comprising a photo-elastic element for differentially alternating the characteristics of said polarization modes in response to the application of a stress, means for applying a torque proportional to said force to said element and stressing said element about the axis of the laser beam to produce a frequency difference between said modes, and means for detecting said frequency difference.
Claim 3
Dependent Claim
29 words
A device as in claim 1 in which said laser beam generator includes a laser tube and at least three reflectors forming a ring laser cavity for said tube.
Claim 4
Dependent Claim
17 words
A device as in claim 1 in which said laser beam generator is a gas laser tube.
Claim 5
Dependent Claim
39 words
An accelerometer comprising, in combination, a force-responsive measurement device as in claim 1, a body having mass, means for supporting said body and said photo-elastic element, and means for converting the acceleration force of said mass into said force.
Claim 6
Dependent Claim
24 words
A gravimeter comprising an aCcelerometer as in claim 4 arranged so that the force of gravity acts on said body to develop said force.
Claim 7
Dependent Claim
16 words
A gravimeter as in claim 5 in which said body comprises components of the gravimeter itself.
Claim 8
Dependent Claim
35 words
A pressure altimeter comprising a force-responsive device as in claim 1 with means for varying the torque applied to said element as a function of the degree of vacuum existing at the altitude in question.
Claim 9
Dependent Claim
32 words
A pressure measurement device comprising a force-responsive measurement device as in claim 1 with means for varying the torque applied to said element as a function of the pressure to be measured.
Claim 10
Dependent Claim
73 words
A device as in claim 1 including reflector means forming a ring cavity for said waves, said waves being counter-rotating laser waves developed in said ring cavity, said photo-elastic element being located in the path of said waves in said ring cavity, means for extracting the counter-rotating beams from the cavity and beating them together to develop a beat frequency signal and means for transmitting said beat frequency signal to said detecting means.
Claim 11
Dependent Claim
63 words
A force measurement method comprising generating electromagnetic waves in the form of a laser beam with a plurality of circular polarization modes, using forceresponsive photo-elastic means and rotational stress-producing means to differentially modulate said polarization modes in accordance with said force to produce a frequency difference which is a function of said force, and converting the frequency units into corresponding units of force.
Claim 12
Dependent Claim
63 words
A force measurement method comprising generating electromagnetic waves in the form of a laser beam with a plurality of circular polarization modes, using forceresponsive photo-elastic means and rotational stress-producing means to differentially modulate said polarization modes in accordance with said force to produce a frequency difference which is a function of said force, and converting the frequency units into corresponding units of force.
Claim 13
Independent Claim
73 words
A method of measuring force-actuated phenomena, said method comprising creating counter-rotating beams in a ring laser system, applying a force to means for converting said force into a torque and applying said torque to create rotational stress in a photo-elastic modulator in the paths of said beams for creating differential effects on said counter-rotating beams, extracting and combining said beams to form a beat signal, and measuring the frequency of said beat signal.
Claim 14
Independent Claim
73 words
A method of measuring force-actuated phenomena, said method comprising creating counter-rotating beams in a ring laser system, applying a force to means for converting said force into a torque and applying said torque to create rotational stress in a photo-elastic modulator in the paths of said beams for creating differential effects on said counter-rotating beams, extracting and combining said beams to form a beat signal, and measuring the frequency of said beat signal.
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) | 1977-01-21 | 1977-07-23 | 1978-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-21 | 1981-07-23 | 1982-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-21 | 1985-07-23 | 1986-01-22 | $7700.00 | Window Closed / Lapsed |