Optical waveguides – Optical waveguide sensor – Including physical deformation or movement of waveguide
Patent
1997-03-17
1999-01-19
Lee, John D.
Optical waveguides
Optical waveguide sensor
Including physical deformation or movement of waveguide
385147, G01S 378
Patent
active
058622748
DESCRIPTION:
BRIEF SUMMARY
BACKROUND OF THE INVENTION
The invention relates to an apparatus for the assessment of the damage to a ship, for instance to the ship's hull, comprising a distributed system of optical fibres positioned near the ship's hull, which optical fibres are connected to a central unit designed for determining the transmission or reflection characteristics of the optical fibres, for enabling the assessment of any possible damage.
DISCUSSION OF THE BACKROUND
It stands to reason that the apparatus is required to be extremely rugged and reliable such that also in the event of major damage to the ship, the apparatus will continue to yield reliable information. An advantageous embodiment of the invention is thereto characterised in that the central unit is disposed in an at least substantially central position inside the ship. This position is all the more favourable because the information supplied by the central unit will usually have to be passed on to a command station that also takes up a central position inside the ship.
It will be obvious that damage reporting will be more accurate as the distributed system of optical fibres is more extensive or in fact, as the number of the optical fibres per unit of surface area increases. A favourable compromise in this respect is characterised in that per deck the system of optical fibres comprises at least one optical fibre which at least substantially horizontally stretches along the entire interior perimeter of the ship's hull.
In case of larger ships, the system of optical fibres per deck may comprise at least one optical fibre which at least substantially horizontally stretches along the interior perimeter of the ship's hull via the bow and at least one optical fibre which at least substantially horizontally stretches along the interior perimeter of the ship's hull via the stern. This then entails the additional advantage that damage to the ship's bow and stern can be accurately assessed at the same time.
A vertical application of several substantially parallel optical fibres is also possible, for instance with 1 metre gaps, which enables a more accurate damage assessment in vertical direction.
A further favourable embodiment of the invention is characterised in that for each optical fibre, the central unit comprises an Y splitter at a first end and an Y splitter at a second end, each provided with a light source and detection means. This enables the optical fibre to be operated in transmission and in reflection, which ensures an optimal use. In this embodiment, the detection means connected to the first end are generally arranged for the detection, in transmission, of light emitted by the light source connected to the second end and the detection means connected to the second end are arranged for the detection, in transmission, of light emitted by the light source connected to the first end; furthermore, the detection means connected to an end are arranged for the detection, in reflection, of light emitted by the light source connected to said end.
To prevent mutual interference of the four combined measuring systems thus obtained, an advantageous embodiment is characterised in that the light source connected to the first end and the light source connected to the second end are at least substantially alternately active.
Since one of the objects of the present invention is to use the apparatus for assessing the size of a hole in the ship's hull, the light source will one way or another have to be modulated for thus creating a range resolution at least in reflection. A further favourable embodiment of the invention is thereto characterised in that both light sources alternately emit a light pulse with a length that matches the desired range resolution.
An extremely rugged embodiment of the invention is characterised in that the means for affecting the transmission or reflection characteristics comprise passive means only, which implies that platform infrastructure provisions, such as power supply lines or cooling water pipes etc. are locally not required for measuring
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patent: 5136235 (1992-08-01), Brandle et al.
patent: 5293039 (1994-03-01), Mongiols
patent: 5592149 (1997-01-01), Alizi
Hollandse Signaalapparaten B.V.
Kang Ellen E.
Lee John D.
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