Abstract: An apparatus for determining displacement of an object, comprises a light source which propagates a polychromatic light signal along a path of a detector, the detector being capable of detecting the intensity of incident radiation at a plurality of different wavelengths, and a radiation modulation means mechanically coupled to said object for movement therewith, displacement of the object being arranged to cause displacement of the radiation modulating means in said path such as to vary the distributed spectral content of the light reaching the detector.In one embodiment the radiation modulation means comprises a filter which attenuates the intensity of transmitted wavelengths to different degrees and which is mechanically coupled to said object such that movement of the object displaces the filter so as to vary the extent to which the filter intercepts the radiation signal propagated by said light source.

Abstract: An apparatus for determining displacement of an object, comprises a light source which propagates a polychromatic light signal along a patch to a detector, the detector being capable of detecting the intensity of incident radiation at a plurality of different wavelengths, and a radiaiton modulation means mechanically coupled to said object for movement therewith, displacement of the object being arranged to cause displacement of the radiation modulating means in said path such as to vary the distributed spectral content of the light reaching the detector.In one embodiment the radiation modulation means comprises a filter which attenuates the intensity of transmitted wavelengths to different degrees and which is mechanically coupled to said object such that movement of the object displaces the filter so as to vary the extent to which the filter interceps the radiation signal propagated by said light source.

Abstract: An apparatus for determining displacement of an object, comprises a light source which propagates a polychromatic light signal along a path to a detector, the detector being capable of detecting the intensity of incident radiation at a plurality of different wavelengths, and a radiation modulation means mechanically coupled to said object for movement therewith, displacement of the object being arranged to cause displacement of the radiation modulating means in said path such as to vary the distributed spectral content of the light reaching the detector.In one embodiment the radiation modulation means comprises a filter which attenuates the intensity of transmitted wavelengths to different degrees and which is mechanically coupled to said object such that movement of the object displaces the filter so as to vary the extent to which the filter intercepts the radiation signal propagated by said light source.