Patent EP0489525A2 successfully refreshed from Google Patents.
EP0489525A2
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EP
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Improvements relating to optical sensing systems
Assignee: BAE Systems Electronics Ltd
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Filing: 1991-11-26
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Granted: —
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Expires: 2011-11-26
Abstract
Abstract An optical sensing system (e.g. hydrophone) comprises a plurality of laser light sources (1,2) for producing light signals of different frequencies (W1,W2) which are combined by a Bragg cell (5) and launched into a single optical fibre (P) leading to an optical sensor array arrangement (11,12). This sensor array arrangement comprises a plurality of optical sensors (13) separated by redirecting means for redirecting light signals along an optical fibre (P) in time displaced relationship to an optical detector.
Inventors
- 👤 Michael Laurence Henning
- 👤 Philip John Nash
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 18:09
CPC Classifications
H; H04; H04J; H04J14/00; H04J14/02; G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/293; G02B6/29304; G02B6/29316; G02B6/29317; G02B6/29322
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
103 words
An optical sensing system comprising a plurality of coherent light sources (1, 2) for producing light signals of different wavelengths, means for combining and launching the light signals of different wavelengths (w1, w2) into a single optical fibre (9) leading to an optical sensor array arrangement which consists of a plurality of optical sensors (23, 24) separated by redirecting means (25, 26) for directing light signals propagated along the sensor array arrangement along an optical fibre (9) in time displaced relationship to an optical detector arrangement (17), wherein different redirecting means (25, 26) are associated with light signals from different sources (1, 2).
Claim 2
Dependent Claim
43 words
An optical sensing system as claimed in claim 1, in which the optical sensor array arrangement comprises two similar arrays connected in parallel into which light signals of respective wavelengths are directed from the single optical fibre by a wavelength dependent optical coupler.
Claim 3
Dependent Claim
93 words
An optical sensing system as claimed in claim 1, in which the optical sensor array arrangement comprises a single array consisting of a plurality of optical sensors connected in series and divided into two parts with the sensors in one part being separated by redirecting means which only redirect light signals of one wavelength but allow continued propagation along the fibre of the light signals of the other wavelength with low loss and with the sensors of the other part being separated by redirecting means which redirect light signals of said other wavelength.
Claim 4
Dependent Claim
59 words
An optical sensing system as claimed in claim 1, in which the optical sensor array arrangement comprises a single array consisting of a plurality of optical sensors which are separated by partial redirecting means alternate ones of which redirect light signals of the different wavelengths but allow continued propagation along the fibre of the signals of the other wavelength.
Claim 5
Dependent Claim
64 words
An optical sensing system as claimed in any preceding claim, in which the means for combining and launching the light signals of different wavelengths from the light sources into the single optical fibre comprises a Bragg cell which produces different deflections of input light signals at different wavelengths which are then combined into the single optical fibre by means of a wavelength dependent coupler.
Claim 6
Dependent Claim
57 words
An optical sensing system as claimed in any preceding claim, in which the means for combining and launching the light signals of different wavelengths into the single optical fibre comprise a Bragg cell which is arranged to be pulsed sequentially at different predetermined frequencies in order to produce like deflections of incoming light signals at different wavelengths.
Claim 7
Dependent Claim
31 words
An optical sensing system as claimed in any preceding claim wherein said redirecting means comprises partial reflectors for reflecting light signals back along the single optical fibre to the detector arrangement.
Claim 8
Dependent Claim
16 words
An optical sensing system as claimed in claim 7 wherein said reflectors comprise reflective optical couplers.
Claim 9
Dependent Claim
46 words
An optical sensing system as claimed in claim 5 or 6 or in any preceding claim dependent thereon in which the reflected signals are picked-off the return path to the Bragg cell by pick-off coupler means which convey the reflected signals to the optical detector arrangement.
Claim 10
Dependent Claim
42 words
An optical sensing system as claimed in any one of claims 1 to 6 wherein the redirecting means comprise optical coupling means for redirecting light to an optical fibre other than said single optical fibre for transmission to the optical detector arrangement.
Claim 11
Dependent Claim
27 words
An optical sensing system as claimed in any preceding claim, in which the redirected light signals are directed on to a single or respective photo-diode detector means.
References Cited (Backward Citations)
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