Fig. 1. Structural diagram of CaF2 crystal

Fig. 2. CaF2 crystal. (a) Transmission spectrum; (b) relationship between refractive index and wavelength[4]

Fig. 3. SEM images of laser-damaged CaF2. (a) Irradiated by ten ArF laser pulses (6.7 J/cm2); (b) irradiated by six ArF laser pulses (7.8 J/cm2)

Fig. 4. SEM images of damage topographies of CaF2 (111) surfaces radiated by laser with different fluences. (a) Conventional standard polish,27.6 J/cm2; (b) diamond turned surface,30 J/cm2; (c) chemo-mechanically polished surface, 57.7 J/cm2; (d) terrace area of cleaved surface, 46 J/cm219

Fig. 5. Time-resolved photoluminescence spectra of CaF2 specimen under excitation with ArF excimer laser pulse. (a) Excimer grade A; (b) excimer grade B; (c) UV grade[22]

Fig. 6. ArF-induced absorption spectra of sodium-doped CaF2 crystal (sample A) and typical pure-CaF2 crystal (sample B)[25]

Fig. 7. Laser induced damage thresholds under excitation of ArF excimer[28]

Fig. 8. Relationship between laser damage threshold and angle between laser polarization plane and crystal axis orientation of <111> axis[29]

Fig. 9. Laser-induced damage probability as a function of fluence for F-SiO2 protective coating and F-SiO2 protected AR coating[39]