SURVEILLANCE APPLIANCE AND APPLIANCE FOR OBSERVATION OF VEHICLE NUMBER PLATES IN HIDDEN NIGHT SURVEILLANCE OPERATIONS

摘要

A surveillance apparatus, particularly for viewing vehicle number plates in covert, night operations, comprises an illuminator 10 having an array of light-emitting diodes 11 or a source of laser light, and a shuttered, preferably-miniature T.V. camera such as a CCD array. The illuminator emits a series of high-peak pulses of infra-red light 17 outside the range visible to the human eye, which reflect from a number plate 13 to be received by the camera which operates in synchronism with the illuminator. It is preferred to have the illuminator 10 positioned close to the camera lens 15 to minimise the included angle 9 between incident light 17 and reflected light 16. The light pulses may vary in amplitude from pulse to pulse, and the camera may include a band pass optical filter. IMAGE