Qinetiq Limited

Optasense Holdings Limited

Geoffrey A Cranch

Roger Ian Crickmore

An optical fibre sensor assembly comprises a source of a plurality of different frequency substantially monochromatic signals (); a modulator connected to the output of the source to produce a train of output pulses of the monochromatic signals; a plurality of sensor sub-assemblies connected to the output of the modulator, each sub-assembly comprising an optical drop multiplexer (ODM) (), a sensor array () comprising a plurality of sensor elements and an optical add multiplexer (OAM) (); a wavelength demultiplexer (WDM), having an input coupled to the sub-assemblies output; a plurality of detectors, each detector having an input connected to receive a respective output of the WDM and providing at an output thereof a signal corresponding to a respective frequency of the modulated monochromatic signals; and an interrogation system, having a plurality of inputs connected such that each input receives the output signal from a respective detector.

Optical fibre sensor assembly

An optical fiber sensor assembly comprises a source of a plurality of different frequency substantially monochromatic signals (); a modulator connected to the output of the source to produce a train of output pulses of the monochromatic signals; a plurality of sensor sub-assemblies connected to the output of the modulator, each sub-assembly comprising an optical drop multiplexer (ODM) (), a sensor array () comprising a plurality of sensor elements and an optical add multiplexer (OAM) (); a wavelength demultiplexer (WDM), having an input coupled to the sub-assemblies output; a plurality of detectors, each detector having an input connected to receive a respective output of the WDM and providing at an output thereof a signal corresponding to a respective frequency of the modulated monochromatic signals; and an interrogation system, having a plurality of inputs connected such that each input receives the output signal from a respective detector.

Temperature sensing apparatus comprises a source of electromagnetic radiation ( ), a wavelength-selective element ( ) which interacts with radiation emitted from the source ( ) and a detection system ( ) which monitors radiation from the wavelength-selective element ( ). The wavelength-selective element ( ) is fixedly mounted on a substantially rigid substrate (not shown). The apparatus can be used for temperature sensing in aquatic environments.

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Dorset, United Kingdom

Geoffrey A Cranch