An MPE-based assessment for a Laser Directed Energy Weapon (LDEW) system with a High Energy Laser (HEL) output will likely result in an impracticably large Laser Hazard Zone. An alternative probabilistic evaluation of the potential hazard may result in less onerous restrictions on the permitted laser firing envelope. However, a risk-based assessment similar to that used in the UK for target designator and rangefinder systems has yet to be developed for LDEW-type laser hazards.
The probabilistic technique accounts for the entire risk chain from laser source to irradiated observer. Unlike a deterministic evaluation, the probabilistic method requires the definition of an acceptable level of observable biophysical damage for eye or skin, from which the risk of the observer sustaining a laser-induced injury may be determined. The permitted restrictions on laser firing are then defined by the maximum allowable risk of an observer sustaining the maximum acceptable level of biophysical damage. This paper will briefly summarize the UK probabilistic method and consider the possible definition of acceptable biophysical damage limits for the risk-based evaluation of LDEW-type laser hazards.