Abstract: A bistatic laser radar (lidar) device is described that comprises a transmit channel (60) for forming a focused transmit beam, and a receive channel (62) for forming a focused receive beam. The device is arranged such that the focus of the transmit beam and the focus of the receive beam fall on a common axis when focused to a distance within the operable distance range of the device. The device may be used for vibrometry, wind speed measurements and the like. Implementation of such a device using optical fiber based components is described.

Abstract: This invention relates to a pattern recognition correlator in which a serial input data signal is converted into a parallel data signal for correlation with one or more reference data signals. The invention relates to use of a demultiplexer in such a correlation apparatus to reduce the data update rate for the subsequent components. The invention also relates to the use of a series of latch circuits to provide serial to parallel conversion of the input data signal in the electrical domain.

Abstract: This invention relates to a pattern recognition correlator and method for correlating input data with one or more reference data sets. The input data, which may be for instance digital amplitude modulated optical data, is used to modulate an optical signal to form a phase modulated optical signal. This temporal phase modulated optical signal is then converted into a parallel optical phase signal, preferably through use of an optical delay, and modulated by an optical phase modulator. When there is a correlation between the input data and the reference data the emerging wavefront is plane and can be strongly coupled to a detector. In the absence of correlation the emergent wavefront is not plane and so is not coupled as strongly to the detector. The detector output can therefore be used as an indication of correlation.

Abstract: Apparatus for indicating the departure of a shape of an object (3;11;16;18;22;26) from a specified shape is described. The apparatus comprises radiation means for directing an incident beam of radiation (4) onto the object, and inspecting means (5) for inspecting the final beam after transmission by or reflection from said object. The apparatus is arranged so that the final beam will have a substantially planar wavefront when said object has said specified shape, and said inspecting means (5) is arranged to determine any departure of the wavefront of the final beam from planarity. In one embodiment, the inspecting means comprises beamsplitting means, for example a diffraction grating (6) or hologram, and detector means such as a CCD camera (8). The beamsplitting means is then arranged to split the final beam into two or more beams and to direct said two or more beams to laterally displaced locations on the detector means.

Abstract: Apparatus for indicating the departure of a shape of an object from a specified shape is described. The apparatus includes a light source for directing an incident beam of radiation onto the object, and an inspecting device for inspecting the final beam after transmission by or reflection from the object. The apparatus is arranged so that the final beam will have a substantially planar wavefront when the object has the specified shape, and said inspecting device is arranged to determine any departure of the wavefront of the final beam from planarity. In one embodiment, the inspecting device includes a beamsplitter, for example a diffraction grating or hologram, and a detector such as a CCD camera. The beamsplitter is then arranged to split the final beam into two or more beams and to direct the two or more beams to laterally displaced locations on the detector.

Abstract: Optical apparatus for simultaneously focussing first and second coaxially spaced object planes in respective separate first and second areas of a common image plane 13 (such as the sensor of a CCD camera) comprises non-diffractive beamsplitter means for receiving light from said object planes along a common path 2 for transmission to said first and second image areas along respective first and second optical paths 3, 4, and reflective or transmissive focussing means 8 arranged to bring said first and second object planes into focus in said first and second areas. The object planes may be differentiated by having different length paths 3,4 (different physical lengths and/or using a differential optical delay), and/or by having different focussing powers in the two paths. In an add-on for a camera, differently curved mirrors of long focal length modify the main camera lens. Polarising optics may be used to separate the two images. The apparatus may be used for 3-D imaging or wavefront analysis.

Abstract: This invention relates to a pattern recognition correlator in which a serial input data signal is converted into a parallel data signal for correlation with one or more reference data signals. The invention relates to use of a demultiplexer in such a correlation apparatus to reduce the data update rate for the subsequent components. The invention also relates to the use of a series of latch circuits to provide serial to parallel conversion of the input data signal in the electrical domain.

Abstract: This invention relates to a proximity sensor. An illumination means (2) projects an array of spots (40) towards a scene. Detector (8) looks towards the scene through a mask (6). The mask (6) is arranged such that light from a target at a certain range, for instance far object (14) is not transmitted to the detector. Light reflected from a close object (16) however passes through the mask (6) and is incident on the detector (8). A rise in the intensity of incident light at the detector (8) is determined by threshold detector (10) and used to operate an alarm (12).

Abstract: This invention relates to a pattern recognition correlator implemented entirely in the electronic domain. The correlator has a serial to parallel conversion means to convert input serial binary data into at least one input parallel binary electrical signal and a comparator to compare the or each input parallel data signal with a reference parallel binary data signal. The serial to parallel conversion means may comprises a demultiplexer to effectively slow the data update rate and a series of latch circuits to provide the parallel data signal. The comparator may be arranged to perform bit addition and may be arranged such that a zero total sum is an indication of correlation. The bit addition may be performed b an array of logic gates.