The direct absorption measurement of fused silica, CaF2, MgF2, and sapphire at VUV and IR region

Abstract

The absorption of fused silica, CaF2, MgF2, and sapphire at VUV region (193.4 nm) and IR region (1070 nm) were measured. For this measurement, LID (Laser Induced Deflection) method was used because of its high sensitivity. We report the degradation behavior of materials by comparison of absorption before and after ArF laser irradiation, and also the ultra-minute absorption at IR wavelength. At each wavelength, the absorption of low OH fused silica before the laser irradiation showed the smallest. At ArF wavelength, sapphire and CaF2 showed higher laser durability than MgF2 and fused silica. At IR wavelength, VUV-transmissive sapphire showed a lower absorption compared to general sapphire.