US3656853A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Interferometric system
Assignee: HP Inc
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Filing: 1969-03-10
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Granted: 1972-04-18
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Expires: 1989-03-10
Abstract
Abstract A portion of a first laser light beam of one optical frequency and a portion of a second laser light beam of a different optical frequency are mixed by a photoelectric device to produce an electrical reference signal having a countable intermediate frequency. Another portion of the first laser light beam traverses a fixed length optical path of an interferometer, and another portion of the second laser light beam traverses a variable length optical path of the interferometer. These other portions of the first and second laser light beams are mixed by another photoelectric device to produce an electrical information signal having the same countable intermediate frequency as the reference signal only while the optical length of the variable length optical path is not being changed. A reversible counter integrates the difference in frequency between the reference and information signals while the optical length of the variable length optical path is being changed to indicate the change in length of the variable length optical path.
Inventors
- 👤 Alan S Bagley
- 👤 Leonard S Cutler
- 👤 Joseph F Rando
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 01:43
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/02001; G01B9/02007; G01B9/02002; G01B9/02003; G01B9/02055; G01B9/0207; G01J; G01J9/00; G01J9/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
497 words
An interferometric system comprising: a laser for emitting a first light beam of a first circular polarization and a first optical frequency and for emitting a parallel and overlapping second light beam of a second circular polarization and a second optical frequency; a quarter-wave plate optically coupled to said laser for converting the first circular polarization of the first light beam to a first linear polarization and for converting the second circular polarization of the second light beam to a second linear polarization; an interferometer having first and second optical paths with the optical length Of said second optical path being variable relative to the optical length of said first optical path; said interferometer including a beam splitter optically coupled to said quarter-wave plate for reflecting a first portion of each of the first and second light beams along said first optical path and for transmitting a second portion of each of the first and second light beams along said second optical path; a first polarization filter mounted in said first optical path for passing substantially only the first portion of the first light beam along said first optical path; a second polarization filter mounted in said second optical path for passing substantially only the second portion of the second light beam along said second optical path; said interferometer including first reflecting means mounted in said first optical path for reflecting the first portion of the first light beam along said first optical path back to a recombination region of said beam splitter; said interferometer including second reflecting means mounted in said second optical path for reflecting the second portion of the second light beam along said second optical path back to the recombination region of said beam splitter; a mixing polarizer optically coupled to the recombination region of said beam splitter for providing the first portion of the first light beam and the second portion of the second light beam with components of similar polarization; a photoelectric detector optically coupled to said mixing polarizer for combining the first portion of the first light beam and the second portion of the second light beam to produce an electrical information signal having a frequency equal to the difference in optical frequency between the first portion of the first light beam after it has traversed said first optical path and the second portion of the second light beam after it has traversed said second optical path; a frequency synthesizer electrically coupled to said photoelectric detector for multiplying the frequency of the electrical information signal by a selected factor; and output means electrically coupled to said frequency synthesizer and responsive to a change in the frequency of the electrical information signal while the optical length of said second optical path is being varied relative to the optical length of said first optical path for providing an indication related to the change in the optical length of said second optical path relative to the optical length of said first optical path.
Claim 2
Dependent Claim
497 words
An interferometric system comprising: a laser for emitting a first light beam of a first circular polarization and a first optical frequency and for emitting a parallel and overlapping second light beam of a second circular polarization and a second optical frequency; a quarter-wave plate optically coupled to said laser for converting the first circular polarization of the first light beam to a first linear polarization and for converting the second circular polarization of the second light beam to a second linear polarization; an interferometer having first and second optical paths with the optical length Of said second optical path being variable relative to the optical length of said first optical path; said interferometer including a beam splitter optically coupled to said quarter-wave plate for reflecting a first portion of each of the first and second light beams along said first optical path and for transmitting a second portion of each of the first and second light beams along said second optical path; a first polarization filter mounted in said first optical path for passing substantially only the first portion of the first light beam along said first optical path; a second polarization filter mounted in said second optical path for passing substantially only the second portion of the second light beam along said second optical path; said interferometer including first reflecting means mounted in said first optical path for reflecting the first portion of the first light beam along said first optical path back to a recombination region of said beam splitter; said interferometer including second reflecting means mounted in said second optical path for reflecting the second portion of the second light beam along said second optical path back to the recombination region of said beam splitter; a mixing polarizer optically coupled to the recombination region of said beam splitter for providing the first portion of the first light beam and the second portion of the second light beam with components of similar polarization; a photoelectric detector optically coupled to said mixing polarizer for combining the first portion of the first light beam and the second portion of the second light beam to produce an electrical information signal having a frequency equal to the difference in optical frequency between the first portion of the first light beam after it has traversed said first optical path and the second portion of the second light beam after it has traversed said second optical path; a frequency synthesizer electrically coupled to said photoelectric detector for multiplying the frequency of the electrical information signal by a selected factor; and output means electrically coupled to said frequency synthesizer and responsive to a change in the frequency of the electrical information signal while the optical length of said second optical path is being varied relative to the optical length of said first optical path for providing an indication related to the change in the optical length of said second optical path relative to the optical length of said first optical path.
References Cited (Backward Citations)
US3249936A
Cited
US3409369A
Cited
US3409375A
Cited
US3453557A
Cited
US3458259A
Cited
US3463924A
Cited
US3583573A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-18 | 1975-10-18 | 1976-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-18 | 1979-10-18 | 1980-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-18 | 1983-10-18 | 1984-04-18 | $7700.00 | Window Closed / Lapsed |