Laser diode illuminator for night vision on-board a 155-mm artillery shell

Having shown the feasibility of passive daytime observation on board of a 155mm gyrostabilized artillery shell, the French-German Research Institute of Saint-Louis (ISL) has started working on projectile boarded night vision systems. Laser illumination was preferred over the use of passive IR imaging mainly for reasons of detector performance and cost. The active imaging system designed for artillery shells will have to undergo accelerations of the order of 15000 g. It will begin the observation of the target area about 1000 m before impact and transmit the images to the ground station before its destruction. A laser illuminator with a peak power of 1 kW before beam shaping and a pulse duration of 50 μs with a repetition rate of 25Hz has been developed for this application. It is based on a laser diode stack emitting at 800nm. A special atten-tion has been given to the beam shaping operation. The beam divergence closely matches the field of view of the imaging optic and has a constant and homogeneous intensity profile over the target. Other fundamental criteria have also been taken into account, such as a compact size, simplicity and low cost, without losing the efficiency of the collimator. A prototype of the active imaging system with a field of view of 10° has been built, tested and validated on the ground. Integration of the illuminator into a 155 mm shell has begun.