HEL atmospheric propagation: extreme stray light events

The propagation of a high-energy laser (HEL) beam through the atmosphere causes stray light emission of much higher average intensity than from conventional cw or pulsed laser sources. Particularly interesting are the events of laser emission interaction with aerosol and dust particles, leading to powerful scattered radiation pulses. Their peak power may significantly exceed the average level of the scattered emission and may seriously impact evaluation of nominal ocular hazard distance (NOHD) and thus laser safety aspects of HEL outdoor operations.