Threat`s e.g. air-to-air missile, pursuit and counter-measure device for e.g. cargo aircraft, has infrared laser source and orientation head with prisms whose refractive index difference introduces large optical path difference of sub beams

摘要

The device has an infrared laser source, and an orientation head to receive an incident coherent light beam and deflect it to produce a transmitted beam. The head has a double prism with prisms (11, 12) in different materials and dividing the transmitted beam into sub beams. The difference of refractive index between the prisms (11, 12) introduces an optical path difference, between the sub beams, greater than coherence length of the incident beam.