Method of testing optical materials by irradiating with high energy density radiation, optical materials selected by said method and uses thereof

An optical material for making optical components for lithographic applications, wherein said optical material is selectable by a testing method, said testing method comprising the steps of:

• a) irradiating an optical material to be tested with ultraviolet radiation at an excitation wavelength below 250 nm, determining intrinsic fluorescence intensity at 285 nm and non-intrinsic fluorescence intensity at a wavelength of 740 nm, and subsequently determining a ratio of the non-intrinsic fluorescence intensity to the intrinsic fluorescence intensity;
• b) if said ratio determined in step a) is less than 1:100, then irradiating the optical material to be tested with laser light and measuring a difference between respective absorptions at a wavelength of 385 nm before and after irradiation with the laser light;
• c) if said ratio determined in step a) is less than 1:100, then irradiating the optical material with an energetic radiation source until saturation is achieved and measuring a difference of respective surface integrals of corresponding absorption spectra between respective wavelength limits of 240 nm and 300 nm before and after irradiation with said energetic radiation source;
• and
• d) establishing that the permanent radiation damage of the optical material is sufficiently small and selecting the optical material for making optical components for lithographic applications from the optical material when said difference between the respective absorptions at the wavelength of 385 nm before and after irradiation with the laser light is <2.5×10−3 cm−1 and the difference of the respective surface integrals between the respective wavelength limits of 240 nm and 300 nm before and after irradiation with the energetic radiation source is <50×10−3 cm−1.