Abstract: In coded aperture imaging knowledge of the coded array pattern and its positional relation to the detector array is needed in order to be able to reconstruct the scene image. Usually a theoretical model of the coded array is used and the actual array needs to be aligned accurately with respect to the detector. The present invention uses a coded aperture imager to image a reference object in the scene and uses the intensity pattern on the detector array to determine the decoding pattern corresponding to the coded aperture array. The reference object may be a point source in which case the pattern on the detector array may be used directly as the decoding pattern or it may be used to correct a theoretical pattern for any misalignment.

Abstract: A micro-opto-electro-mechanical systems (MOEMS) electro optical modulator (2) having an electrically tuneable optical resonator comprising an asymmetric Fabry-Perot etalon incorporating a mirror (10) resiliency biased with respect to a substrate (13) and moveable in relation thereto in response to a voltage applied there-between. The optical modulator (2) is capable of modulating electromagnetic radiation having a plurality of wavelengths. The modulator is adapted to modulate the transmission of short wave infrared radiation (SWIR), medium wave infrared radiation (MWIR) and long wave infrared radiation (LWIR) and the reflection of visible radiation. A spatial optical modulator having a plurality of said MOEMS optical modulators (2). A method of addressing said spatial optical modulator.

Abstract: A micro-opto-electro-mechanical systems (MOEMS) electro optical modulator (2) having an electrically tuneable optical resonator comprising an asymmetric Fabry-Perot etalon incorporating a mirror (10) resiliency biased with respect to a substrate (13) and moveable in relation thereto in response to a voltage applied there-between. The optical modulator (2) is capable of modulating electromagnetic radiation having a plurality of wavelengths. The modulator is adapted to modulate the transmission of short wave infrared radiation (SWIR), medium wave infrared radiation (MWIR) and long wave infrared radiation (LWIR) and the reflection of visible radiation. A spatial optical modulator having a plurality of said MOEMS optical modulators (2). A method of addressing said spatial optical modulator.

Abstract: An optical interference filter (2) is provided by a substrate (1) in which is formed a plurality of parallel slots so as to define layers (slots and substrate laminae) of alternating refractive index. As shown, the filter comprises a central Fabry-Perot resonator slot cavity (3) between two mirror groups (4, 5) of alternating slots and substrate laminae, and is coupled to optical fibers (7) accommodated in V-grooves (6) on either side. For tuning, one mirror group (5) may be movable in the direction of arrow (A), or, where the central resonator is provided by substrate material, by altering its temperature. One or more further Fabry-Perot filters may be formed in the substrate and coupled to the filter (2). The invention encompasses non-resonating filters.

Abstract: An optical substrate is provided with a surface of a desired shape by coating the surface with a thin layer of an optical glass and subsequently modifying the shape of the external surface of the layer. In preferred embodiments, the temperature of the substrate is maintained at substantially less than 400° C., the substrate is an optical component other than a simple window, and the refractive index o the optical glass is within 20% of the refractive index of the material providing the surface to be coated. One particular use is when both the substrate (e.g. a non-linear optical layer) and the optical glass are optically transmissive in the near infra-red and/or mid infra-red ranges. The glass layer can compensate for physical imperfections in the surface. It can be polished to optical quality, or provide with detail across the coated surface, e.g. as a “moth-eye” anti-reflection layer, or a diffractive or interference structure.

Abstract: An optical interference filter (2) is provided by a substrate (1) in which is formed a plurality of parallel slots so as to define layers (slots and substrate laminae) of alternating refractive index. As shown, the filter comprises a central Fabry-Perot resonator slot cavity (3) between two mirror groups (4, 5) of alternating slots and substrate laminae, and is coupled to optical fibres (7) accommodated in V-grooves (6) on either side. For tuning, one mirror group (5) may be movable in the direction of arrow (A), or, where the central resonator is provided by substrate material, by altering its temperature. One or more further Fabry-Perot filters may be formed in the substrate and coupled to the filter (2). The invention encompasses non-resonating filters.

Abstract: Apparatus for distinguishing between genuine and counterfeit articles whereby a first optical filter is applied to genuine articles and suspect articles are scanned with the aid of a suitable second optical filter. Scanning of genuine articles incorporating first optical filter with the aid of suitable second optical filter gives rise to optical effects which would not otherwise be apparent.

Abstract: An optical component having a protective layer provided on a surface thereof, the protective layer preventing the component from being damaged by high velocity impacts from small particles or water droplets. The protective coating comprises a layer of gallium phosphide deposited onto the component surface using plasma assisted chemical vapour deposition (PACVD), an intermediate layer of PACVD boron phosphide, and an outer layer of PACVD diamond-like-carbon.