Optical strength of coated metal optics subjected to cw radiation

An analysis is made of the role of various physical mechanisms that can damage a cooled coated metal mirror. Two types of damage are considered: reversible and irreversible. The absorption of radiation in the coating and for the removal of heat are allowed for in determination of the distribution in an electromagnetic field, a temperature field, and a field of thermoelastic strains in the system. Criteria are obtained of the optical damage, due to a critical deviation of the parameters of the system from the calculated values, and of the optical damage by cracking, flaking, and bulging of the coating during operation. The thermal instability criterion of the system is also derived.