Researches On Intense Laser Indused Damage Of The Photoelectric Detectors

Photoelectric detectors (PE) used in military applications may be exposed to laser irradiation of high irradiance or energy density causing sever damage even failure.Knowledge about laser damage thresholds is relevant consisdering photoelectric countermeasure.In this thesis fundamental researches on intense laser indused damage are performed. Starting from the physical principles of laser-beam interactions with PE detectors,three damage mechanisms are discussed.A possible damage mechanism -backward extrusion effect is proposed. Laser indused thermal stress model is established and analysed.The dependence of damage threshold on laser spot diameter is fomulated and the spot size dependence (spot effect) mentioned with phenomenological explanation is quantatively explained.Based on diffraction theory the effect of thermal lensing of the cavity mirror on the laser beam is studied.By use of a serrated diaphragm and spatial filter technique the laser beam is shaped into a super-Gaussian beam of uniform intensity which improves the accuracy of the laser damage threshold measurement.An experimental system for laser indused damage measurement is designed.The possible measurement errors are qualitatively analysed.The obtained results are of importance for further studies of laser indused damage and anti-damage.