Spectral properties of an UV fused silica within 0.8 to 5 µm at elevated temperatures

A thermal radiative inverse method was used to determine the high-temperature spectral properties of an ultraviolet fused silica from transmittance data for wavelengths from 0.8 to 5 µm. A developed FTIR system used to measure apparent transmittances of the fused silica sample has been designed and built. In order to reduce the system error caused by detector emission and stray radiation, a measurement strategy at high temperatures was proposed. For deriving spectral transport properties from experimental transmittances, the parameter identification principle was described. The results show that spectral properties are both wavelength dependent and temperature dependent. Spectral refractive indexes rise with increasing temperature and decrease with wavelength. Three absorption peaks of spectral absorptive indices respectively at about 1.4 µm, 2.22 µm and 2.75 µm shift toward the far infrared region and vary differently with increasing temperature. In addition, three absorption bands all become broader for temperatures from 20 °C to 900 °C.