Characteristic parameter determining method for optical material i.e. calcium fluoride, in optical component in lithographic system, involves measuring change of absorption coefficients of optical material for determining saturation values

摘要

The method involves determining saturation values of the change of absorption coefficients of an optical material (1) i.e. calcium fluoride, as characteristic parameter of the optical material. The change of the absorption coefficients of the optical material is measured using two irradiations with different irradiation parameters for determining the saturation values. A time constant is determined as the additional characteristic parameter such as number of pulses (N), pulse duration (tau) and power density (H) of the optical material. An independent claim is also included for an optical component comprising optical material.