US3635562A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical interferometer for detection of small displacements
Assignee: Alcatel Lucent SAS
•
Filing: 1968-11-12
•
Granted: 1972-01-18
•
Expires: 1988-11-12
Abstract
Abstract An optical interferometer for detecting small displacements. Two mirrors form a Fabry-Perot cavity. One mirror is mounted to be subject to movement by external displacement forces. The other mirror is subjected to feedback control to reduce low-frequency variations in length of the laser cavity.
Inventors
- 👤 Jean-Michel Catherin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:43
CPC Classifications
G; G01; G01P; G01P15/00; G01P15/02; G01P15/08; G01P15/093; H; H04; H04R; H04R23/00; H04R23/008; G01B; G01B2290/00; G01B2290/25
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
202 words
An apparatus for measuring small movementS comprising: a. a resonant Fabry-Perot cavity including first and second parallel partially reflecting mirrors, said mirrors positioned to be traversed by a beam of monochromatic light from a source directing light into said cavity; b. flexible suspension means for suspending said first mirror such that it is movable in a direction along the axis perpendicular to the plane of said second mirror, the movement of said first mirror caused by some external excitation; c. a control means for fixedly supporting said second mirror and for controlling the distance between said second mirror and said flexible suspension means; d. a photosensitive detector means positioned at the output of said cavity for receiving the light output of said cavity and for producing an electrical output signal in response thereto indicative of the movement of said first mirror; and e. a feedback loop means, having an input connected to the output of said photodetector means and having an output connected to said control means, for supplying a signal to said control means in accordance with the output of said photodetector means, whereby the distance between said second mirror and said flexible suspension means tends to be maintained substantially constant.
Claim 2
Independent Claim
202 words
An apparatus for measuring small movementS comprising: a. a resonant Fabry-Perot cavity including first and second parallel partially reflecting mirrors, said mirrors positioned to be traversed by a beam of monochromatic light from a source directing light into said cavity; b. flexible suspension means for suspending said first mirror such that it is movable in a direction along the axis perpendicular to the plane of said second mirror, the movement of said first mirror caused by some external excitation; c. a control means for fixedly supporting said second mirror and for controlling the distance between said second mirror and said flexible suspension means; d. a photosensitive detector means positioned at the output of said cavity for receiving the light output of said cavity and for producing an electrical output signal in response thereto indicative of the movement of said first mirror; and e. a feedback loop means, having an input connected to the output of said photodetector means and having an output connected to said control means, for supplying a signal to said control means in accordance with the output of said photodetector means, whereby the distance between said second mirror and said flexible suspension means tends to be maintained substantially constant.
Claim 3
Dependent Claim
21 words
The apparatus of claim 1 wherein said flexible suspension means comprises a membrane, said first mirror suspended in the center thereof.
Claim 4
Dependent Claim
35 words
The apparatus of claim 1 wherein said control means comprises a piezoelectric ceramic tube with said second mirror fixedly attached to one end thereof and said flexible suspension means attached to the other end thereof.
Claim 5
Dependent Claim
46 words
The apparatus of claim 3 further comprising means attached to said ceramic tube in the plane of said second mirror for causing the end of said ceramic tube attached to said suspension means to move in a direction perpendicular to the plane of said second mirror.
Claim 6
Dependent Claim
19 words
The apparatus of claim 4 further comprising means for keeping the interior of said cavity at a constant pressure.
Claim 7
Dependent Claim
30 words
The apparatus of claim 3 wherein the surface area of said membrane and said first mirror exposed to said cavity is less than the surface area of said second mirror.
Claim 8
Dependent Claim
36 words
The apparatus of claim 3 further comprising means attached to said ceramic tube at the midpoint thereof for limiting the movement of said ceramic tube in a direction perpendicular to the plane of said second mirror.
Claim 9
Independent Claim
241 words
An apparatus for measuring small movements comprising: a. a monochromatic light beam source; b. a resonant Fabry-Perot cavity including first and second parallel partially reflecting mirrors, said mirrors positioned to be traversed by a first portion of said monochromatic light beam; c. flexible suspension means for suspending said first mirror such that it is movable in a direction along the axis perpendicular to the plane of said second mirror, the movement of said first mirror caused by some external excitation; d. a control means for fixedly supporting said second mirror and for controlling the distance between said second mirror and said flexible suspension means; e. a first photosensitive detector means positioned at the output of said cavity for receiving the light output of said cavity; f. a deflector means for deflecting a second portion of said monochromatic light beam; g. a second photosensitive detector means for detecting said second portion of said monochromatic light beam; h. a comparator means for comparing the output of said first and second photosensitive detector means to provide an output signal indicative of the movement of said first mirror; and i. a feedback loop means having an input connected to said comparator means and having an output connected to said control means, for supplying a signal to said control means in accordance with the output of said comparator whereby the distance between said second mirror and said flexible suspension means tends to be maintained substantially constant.
Claim 10
Independent Claim
241 words
An apparatus for measuring small movements comprising: a. a monochromatic light beam source; b. a resonant Fabry-Perot cavity including first and second parallel partially reflecting mirrors, said mirrors positioned to be traversed by a first portion of said monochromatic light beam; c. flexible suspension means for suspending said first mirror such that it is movable in a direction along the axis perpendicular to the plane of said second mirror, the movement of said first mirror caused by some external excitation; d. a control means for fixedly supporting said second mirror and for controlling the distance between said second mirror and said flexible suspension means; e. a first photosensitive detector means positioned at the output of said cavity for receiving the light output of said cavity; f. a deflector means for deflecting a second portion of said monochromatic light beam; g. a second photosensitive detector means for detecting said second portion of said monochromatic light beam; h. a comparator means for comparing the output of said first and second photosensitive detector means to provide an output signal indicative of the movement of said first mirror; and i. a feedback loop means having an input connected to said comparator means and having an output connected to said control means, for supplying a signal to said control means in accordance with the output of said comparator whereby the distance between said second mirror and said flexible suspension means tends to be maintained substantially constant.
References Cited (Backward Citations)
US2948152A
Cited
US3170122A
Cited
US3395367A
Cited
GB1068054A
Cited
US3470329A
Cited
US3433959A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |