Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Patent
1992-10-12
1994-08-02
Turner, Samuel A.
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
356345, 356346, 25022711, G01B 902
Patent
active
053350650
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a sequential demultiplexing receiver for a network of interferometer optical sensors using spectrum modulation encoding, which network is illuminated by a light source of short coherence length and in which each sensor subjected to a physical magnitude to be measured generates an optical path length difference that is a function of the value of said magnitude, said optical path length differences and the differences between them being greater than the coherence length of the source.
In the prior art, the receiver associated with such a network of sensors may be an interferometer, e.g. of the Michelson type, which is tuned in succession to each of the sensors in the network so as to enable it to produce an optical path length difference that is substantially equal to the mean value of the optical path length difference of the sensor in question, thereby producing an interferometer signal at the output from the interferometer for application to a photodetector, with the phase thereof being a direct function of the difference between the path length difference in the sensor and the path length difference in the receiver, providing said difference is less than the coherence length of the source. Known techniques of phase modulation in the receiving interferometer and of demodulating the interferometer signal produced thereby make it possible to discover the phase of said signal and thus the optical path length difference in the sensor, thereby making it possible to deduce the value of the physical magnitude to be measured on the basis of prior calibration (the optical path length difference in the receiver being known).
Nevertheless, it is relatively lengthy and difficult to tune the receiving interferometer successively to each of the path length differences generated in the sensors.
Another solution in the prior art consists in providing as many receiving interferometers as there are sensors, and in connecting them to the network of sensors via optical fibers and optical couplers in a star configuration, each receiving interferometer being tuned to a corresponding sensor, thereby making parallel demultiplexing possible of the signals provided by the network of sensors. However, that requires as many receiving interferometers to be provided as there are sensors, thereby increasing the overall cost of the system.
SUMMARY OF THE INVENTION
An object of the invention is to provide a single receiver for association with a network of sensors of the above-specified type, and enabling the light signals provided by the network of sensors to be demultiplexed sequentially at a very high rate.
Another object of the invention is to provide a receiver of this type capable of being implemented in the form of an integrated optical circuit.
To this end, the present invention provides a sequential demultiplexing receiver for a network of sensors of the above-specified type, said receiver comprising means enabling path length differences tuned to those of the sensors to be generated in succession and transmitting an interferometer type signal to a photodetector, the receiver being characterized in that it is essentially constituted by an integrated optical circuit having two polarization modes or two transverse modes, the circuit comprising a substrate that is birefringent or semiconductive and on which integrated components are formed for mode coupling or mode conversion by the electro-optical effect, which components are connected in series on the substrate by a light waveguide and are individually connected to means for applying electrical voltage thereto to enable them to be activated sequentially thus generating path length differences matching those of the sensors.
In such a receiver, the required path length differences are generated in succession by the electro-optical effect mode conversion or coupling components, and the use of integrated optical techniques makes it possible to switch these path length differences very quickly.
This receiver may be of
REFERENCES:
patent: 4867565 (1989-09-01), Lequime
patent: 5179424 (1993-01-01), Lequime et al.
patent: 5200796 (1993-04-01), Lequime
patent: 5255068 (1993-10-01), Emo et al.
Lequime Michel
Sansonetti Pierre
Bertin & Cie
Keesee LaCharles P.
Turner Samuel A.
LandOfFree
Sequential demultiplexing receiver for a network of optical sens does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sequential demultiplexing receiver for a network of optical sens, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sequential demultiplexing receiver for a network of optical sens will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-68464