Abstract: Apparatus for non-orthogonal monitoring of a variable measurand in a system or process, comprising: means defining at least three sources having limited spectral widths and non-orthogonal spectral outputs; a modulator means which is adapted to modulate the outputs of said sources in response to said variable measurand; at least three detectors which have non-orthogonal responsivities in the measurement domain and which receive the modulated outputs of said sources; and a processor which converts the detector outputs algorithmically into primary chromatic parameters.

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 optical sensor comprises a polychromatic light source (3), a detector (4), and first and second polarizers (7) (8) disposed in the light path between the source and the detector. The polarization axis of the first polarizer (7) is substantially orthogonal to that of the second (8), and there is a modulating element (6) of birefringent material disposed therebetween. The modulating element is disposed such that a change in the parameter to be measured alters the optical path length of the polychromatic light through the modulating element, thereby changing the color of the light incident on the detector (4). The detector comprises first and second photo-responsive elements (9) (10), the responsivity with respect to wavelength of the first element (9) being different from that of the second (10).

Abstract: An optical sensor includes an optical fibre (1), a polychromatic light source (2) and a detector (3). The optical fibre is disposed such that a change in the parameter to be measured causes a movement of the fibre to vary the amount of microbending such that the portion of the polychromatic light which is no longer constrained within the fibre is varied. The detector (3) detects the intensity of the polychromatic light transmitted by the optical fibre (1) at a plurality of different wavelengths, and a microprocessor (6) interprets the output of the detector (3) in terms of the parameter to be measured.

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.

Abstract: A moire fringe displacement sensor includes first and second gratings (3) (4), a polychromatic light source (1) illuminating the gratings, and a detector (8). The gratings are disposed such that a relative displacement of the first and second gratings causes a variation in the color of the light reaching the detector. The detector (8) comprises first and second photo-responsive elements (11) (12), the responsivity with respect to wavelength of the first element (11) being different from that of the second (12). Signals from the photo-responsive elements are fed to a micro-processor (15) which calculates the color of the light incident on the detector as represented by two or more parameters on the Chromaticity (CIE) Diagram, and interprets the color in terms of the displacement of the first and second gratings.

Abstract: An FET device comprises a substrate with source and drain regions separated by a gate structure. Between the gate and substrate is an insulator formed of a cubic fluorite structure material that is lattice matched within 1% to the substrate. The insulator may be a group II fluoride such as Ca.sub.y Cd.sub.1-y F.sub.2 (0.ltoreq.y.ltoreq.1), Sr.sub.z Ba.sub.1-z F.sub.2 (0.ltoreq.z.ltoreq.1), or Ba.sub.x Ca.sub.1-x F.sub.2 (0.ltoreq.x.ltoreq.1), or an oxide such as CeO.sub.2, PbO.sub.2. The substrate may be a bulk semiconductor or an epitaxial layer such as Si, InP, GaAs, Ga.sub.x Al.sub.1-x As, GaSb, InAs, or AlAs.