Low ambient light level indicator - has light emitting device in field of view of binoculars and becoming visible when ambient light level becomes low

摘要

A pilot (4) having helmet-mounted binoculars (3) which incorporate an image intensifier, views a scene through a transparent canopy (6). An electroluminescent panel (1) has a square face, 3 cm x 3 cm, and is mounted on the canopy (6) to emit light towards the intensifier and is within the binocular field of view (A,A). The panel (1) is fed via wires (2) by a power supply which produces current pulses at 3 Hertz. The supply power level is pre-set to a value such that under hiqh ambient light levels the panel illumination is relatively low and the panel is not noticeable, whereas at low ambient light levels the panel becomes noticeable and the pilot is warned of deteriorating visibility.