Abstract: A radiation detection apparatus comprises a radiation detector and a lens arrangement. The lens arrangement comprises a polarising element and an optical corrector. The optical corrector is preferably located between the polarising element and the radiation detector and has at least one surface designed to correct optical aberrations present in the lens arrangement. The optical corrector may be arranged to provide a mechanical support to the polarising element. The optical corrector is arranged to increase a diffraction limited acceptance angle of the apparatus.

Abstract: A scanning imaging apparatus comprises an optical system including a curved polariser/reflector, a rotatable reflector, a polarisation twisting plate, and a receiver array, wherein a convex reflective element is incorporated in the optical path that acts as a sub-reflector that increases the optical system focal length. It has been found that an increase to the optical focal length in this manner gives a greater 3 dB spot size at the image plane, thus easing design constraints on the receiver array packing density, whilst maintaining a given spatial sampling interval. An additional benefit is that radiation from differing scan locations diverges as it approaches the image plane, which provides more volume in which to position receiver electronics. Focussing of the optical system may be achieved by movement of the sub-reflector.

Abstract: A detection system operable at millimetre or sub-millimetre wavelengths includes detection means adapted to detect radiation at two distinct wavebands, wherein a first waveband is chosen such that it has a relatively high atmospheric absorbency to electromagnetic radiation, and the second waveband is chosen to have a relatively low atmospheric absorbency to electromagnetic radiation. The system is further adapted to take measurements from at least two different regions on a target, and to process the measurements to give an indication that the target contains an object of interest. The processing may comprise comparing measurement differences at a given waveband to reference data obtained from test measurements, or from computer models of targets. The detection system provides the ability to detect objects of interest without the need to provide a millimetric or sub-millimetric image of the target.

Abstract: A system for imaging the contents of containers includes an imager arranged to receive millimetre wave radiation from a reception volume through a receive antenna wherein, in use, the container is moving relative to the receive antenna, the reception volume is positioned such that the relative movement causes the reception volume to move through the container; data from the antenna is recorded as the reception volume moves through the container, and an image of the contents of the container is built up from the recorded data. The system is particularly suitable for imaging containers mounted on vehicles. The imager may advantageously be mounted in a portal, allowing convenient and controllable relative positioning of the container, and allowing the relative speed to be controlled or measured easily. The invention allows 3D or pseudo 3D images to be produced to aid identification of container contents. The invention also includes a method for imaging.

Abstract: A steerable antenna or scanner assembly (10) is connected to signal process means (12). A housing (14) surrounds a focusing antenna (16) which is stationary relative to the housing (14), a polarisation rotator (18), a steerable reflector (20) angularly movable about a pivot axis (22), and a detector (24). Incoming radiation passes through the focusing antenna (16), has its polarization altered as it passes through rotator (18), reflects off reflector (20), Passes through rotator (18) again, encounters the antenna (16) again and this time reflects off it to focus down, passes through rotator (18) again, encounters the steerable reflector (20) again and this time passes through it to reach the detector (24). Moving the reflector (20) angularly steers the directional sensitivity of the assembly (10).

Abstract: A system for imaging the contents of containers includes an imager arranged to receive millimetre wave radiation from a reception volume through a receive antenna wherein, in use, the container is moving relative to the receive antenna, the reception volume is positioned such that the relative movement causes the reception volume to move through the container; data from the antenna is recorded as the reception volume moves through the container, and an image of the contents of the container is built up from the recorded data. The system is particularly suitable for imaging containers mounted on vehicles. The imager may advantageously be mounted in a portal, allowing convenient and controllable relative positioning of the container, and allowing the relative speed to be controlled or measured easily. The invention allows 3D or pseudo 3D images to be produced to aid identification of container contents. The invention also includes a method for imaging.

Abstract: Scanning apparatus which may be used in a real-time passive millimeter wavelength imaging system or in other radiometry systems. The apparatus scans input radiation from a scene and output radiation is transmitted to a receiver system, for example a millimeter wave imaging camera or a radar receiver. The apparatus comprises a rotatable reflective plate having an axis of rotation passing through the centre of its surface and a lens arrangement for selectively transmitting and focusing radiation having a particular direction of polarisation. The apparatus may also comprise a feed horn array comprising a plurality of feed horns, the feed horns forming part of a spherical surface having a radius of curvature substantially equal to R/2 and being concentric with the third substantially spherical polarising element. The apparatus may further comprise a detector array comprising a plurality of detector elements. The detector array may form part of a millimeter wave imaging camera.