Vacuum ultraviolet transmission of aluminum fluoroberyllate glasses

Vacuum ultraviolet (VUV) transmission spectra of aluminium fluoroberyllate glasses, MgF2-CaF2-SrF2-AlF3- BeF2 (MCSA-Be) and MgF2-CaF2-SrF2-AlF3- YF3-BeF2 (MCSAY-Be), were measured in a wavelength region from 130 to 240 nm. The influence of YF3 and BeF2 on the thermal stabilization against crystallization and VUV transmittance was investigated. With increasing the BeF2 content, crystallization tendencies decreased in the MCSA-Be and MCSAY-Be glasses. The MCSA-20Be glass composition exhibited the shortest wavelength of UV absorption edge (approximately 147 nm), and the highest transmittance at 157 nm (60% for 2 mm sample thickness). The transmittance at 157 nm and the slope (steepness) of the absorption edge were found to be significantly influenced by the trace amount of Fe2+.