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EP0023345A2
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Optical sensing system
Assignee: Toshiba Corp
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Filing: 1980-07-23
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Granted: —
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Expires: 2000-07-23
Abstract
Abstract In an optical sensing system a laser beam is split by a 3dB optical directional coupler (6) into two beams which in turn are launched into single mode optical fibers (8, 10) of a different length. Since the two single mode optical fibers (8, 10) are maintained at a temperature to be measured, a phase difference is produced between the beams transmitted through the optical fibers (8, 10). The beams passing through the optical fibers (8, 10) are synthesized by the 3dB optical directional coupler (12) into an optical signal of an amplitude of "light" or "dark". As the wavelength of the light beam monotonously varies, the optical signal has an alternately repeated light- and dark-band pattern. Such optical signal is ' detected as a function of a temperature to be measured.
Inventors
- 👤 Takeshi Ozeki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 16:35
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/353; G01D5/35303; G01K; G01K11/00; G01K11/32
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
99 words
An optical sensing system comprising: means (2) for generating a coherent light beam whose wavelength is monotonously varied with time; means (4) for transferring the coherent light beam; means (6, 32) for dividing the light beam transferred into two beams; means (8, 10, 38) for sensing a physical quantity which produces a phase difference between the two beams; means (12, 32) for synthesizing the two beams to produce an amplitude-modulated optical signal; means (14) for transfering the beam; and means (16, 18) for detecting an amplitude variation of the optical signal transferred, as a function of the physical quantity.
Claim 2
Dependent Claim
99 words
An optical sensing system comprising: means (2) for generating a coherent light beam whose wavelength is monotonously varied with time; means (4) for transferring the coherent light beam; means (6, 32) for dividing the light beam transferred into two beams; means (8, 10, 38) for sensing a physical quantity which produces a phase difference between the two beams; means (12, 32) for synthesizing the two beams to produce an amplitude-modulated optical signal; means (14) for transfering the beam; and means (16, 18) for detecting an amplitude variation of the optical signal transferred, as a function of the physical quantity.
Claim 3
Dependent Claim
29 words
An optical sensing system according to claim 1, in which said means (2) for generating a coherent laser beam causes the light beam to be monotonously increased with time.
Claim 4
Dependent Claim
32 words
An optical sensing system according to claim 1, in which said means (2) for generating a coherent light beam causes the wavelength of the light beam to be monotonously decreased with time.
Claim 5
Dependent Claim
34 words
An optical (2) sensing system according to claim 1, in which said means for generating a coherent light beam causes the wavelength of the light beam to be monotonously varied by a predetermined range.
Claim 6
Dependent Claim
26 words
An optical sensing system according to claim 1, in which said means (6, 32) for dividing the light beam is a 3dB optical directional coupler (6).
Claim 7
Dependent Claim
24 words
An optical sensing system according to claim 1, in which said means (16, 32) for dividing the light beam is a half mirror (32).
Claim 8
Dependent Claim
21 words
An optical sensing system according to claim 1, in which said sensing means (8, 10, 32) is an optical fiber (8).
Claim 9
Dependent Claim
26 words
An optical sensing system according to claim 1, in which said means (12, 32) for synthesizing the two beams is a 3dB optical directional coupler (12).
Claim 10
Dependent Claim
23 words
An optical sensing system according to claim 1, in which means (12, 32) for synthesizing the two beams is a half mirror (32).
Claim 11
Dependent Claim
38 words
An optical sensing system according to claim 1, in which said detecting means (16, 18) includes a photodetector (16) which converts the amplitude-modulated optical signal to a electric pulses and a counter (18) which counts the electric pulses.
Claim 12
Dependent Claim
46 words
An optical sensing system according to claim 1, further comprising means (22, 24, 25) for detecting the predetermined wavelength of the light beam to energize the optical signal detecting means and the predetermined wavelength change of the light beam to deenergize the optical signal detecting means.
Claim 13
Dependent Claim
65 words
An optical sensing system according to claim 11, in which said wavelength detecting means includes a Fabry-Perot reasonator (22) which converts the wavelength varying light beam to an optical inpulses, a photodetector (24) which convents the optical impulses to electric pulses and a counter (25) which counts the electric pulses and generates a start and stop signals supplied to the optical signal detecting means (18).
References Cited (Backward Citations)
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