Patent EP0138623A2 successfully refreshed from Google Patents.
EP0138623A2
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EP
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Test method for optical fibres and apparatus for performing the test method
Assignee: NTT Inc
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Filing: 1984-10-17
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Granted: —
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Expires: 2004-10-17
Abstract
Abstract The optical transmission characteristics of a length of optical fibre are determined by launching a light pulse through non-directional coupling means into one end of the length of fibre, allowing returned light to pass through the light source producing the pulse, and detecting the amount of returned light. The light source may be a semiconductor laser which is energised to a level high enough to cause it to generate the light pulse and which is subsequently energised to a level at which it will be triggered by returned light and amplify the returned light for detection.
Inventors
- 👤 Masamitsu Tokuda
- 👤 Tsuneo Horiguchi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 17:57
CPC Classifications
G; G01; G01M; G01M11/00; G01M11/30; G01M11/31; G01M11/3109; G01M11/3145
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
68 words
A test method for optical fibers comprising the steps of injecting an optical pulse signal into an end of a fibre, and receiving light due to reflection or the backscattering of the said optical pulse signal within the said fibre, the method being characterized in that the said received light from the fibre is made to pass through the light source which generated the said optical pulse signal.
Claim 2
Dependent Claim
68 words
A test method for optical fibers comprising the steps of injecting an optical pulse signal into an end of a fibre, and receiving light due to reflection or the backscattering of the said optical pulse signal within the said fibre, the method being characterized in that the said received light from the fibre is made to pass through the light source which generated the said optical pulse signal.
Claim 3
Dependent Claim
32 words
A test method for optical fibers, as claimed in Claim 1, which includes launching the light pulse from a semiconductor laser and amplifying returned light energy by means of the semiconductor laser.
Claim 4
Dependent Claim
68 words
A test method for optical fibres, as claimed in claim 1 or claim 2, which includes launching the light pulse by energising a semi- conductor laser to a level at which it generates a light pulse, and, after the light pulse is generated, energising the semiconductor laser to a level below which it generates a pulse and at which it amplifies the returned light energy passing through it.
Claim 5
Dependent Claim
110 words
A test apparatus for optical fibers comprising a light source, a circuit for driving the light source to generate optical pulse signals, optical coupling means for coupling output light from the said light source with one end of the said fibre, and receiving means including an optoelectric for receiving light returned, in the fibre, towards the light source and leaving the fibre at the light source end, the apparatus being characterized in that the said receiving means is disposed at the side of the light source remote from the fibre so as to receive light after it has passed through the said optical coupling means and the said light source.
Claim 6
Dependent Claim
110 words
A test apparatus for optical fibers comprising a light source, a circuit for driving the light source to generate optical pulse signals, optical coupling means for coupling output light from the said light source with one end of the said fibre, and receiving means including an optoelectric for receiving light returned, in the fibre, towards the light source and leaving the fibre at the light source end, the apparatus being characterized in that the said receiving means is disposed at the side of the light source remote from the fibre so as to receive light after it has passed through the said optical coupling means and the said light source.
Claim 7
Dependent Claim
67 words
A test apparatus for optical fibers, as claimed in Claim 4, wherein the light source comprises a semiconductor laser, the light source driving circuit is so arranged as to provide driving current of a level at which the semi- conductor laser generates a light pulse, and, subsequently, to provide driving current at a level at which the semiconductor laser amplifies the returned light energy passing through it.
Claim 8
Dependent Claim
51 words
A test apparatus for optical fibers as claimed in Claim 4, wherein the receiving means includes an optical gate circuit which is so controlled as to be in an OFF-state at the times that the light source generates optical pulse signals, and to be in an ON-state for returned light energy.
Claim 9
Dependent Claim
59 words
A test apparatus for optical fibers, as claimed in Claim 6, wherein the optical gate circuit comprises a semiconductor laser, and a means is provided in order to supply driving current at a level which makes the said semi- conductor laser amplify light passing through it at the times when returned light is passing through the optical gate circuit.
Claim 10
Dependent Claim
35 words
A test apparatus for optical fibers, as claimed in Claim 4, wherein a filter is provided between the light source and the receiving means to selectively pass the output light wavelength of the light source.
Claim 11
Independent Claim
18 words
A system including apparatus for testing optical fibres as claimed in any one of claims 4 to 8.
Claim 12
Dependent Claim
19 words
A communication system including apparatus for testing optical fibres as claimed in any one of claims 4 to 8.
References Cited (Backward Citations)
No citation records indexed.
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