LABORATORY PREPARATION OF HIGHLY PURE AS2SE3 GLASS

Arsenic selenide glass samples have been prepared using a combination of heat treatment and distillation techniques to remove impurities. Transmission spectra of the samples in the infrared region (2.5-20 mu m) were measured. The spectra indicate that the majority of absorbing oxide species can be removed by a simple heat treatment. Chemical analysis shows that distilled samples contain less silicon impurity, indicating that Si is most likely incorporated during tube sealing procedures. Increased transmission for the purified samples in the 10-11 mu m range shows the necessity of purification to obtain glasses with good transparency for CO2 laser applications. The highest transmission values at 10.6 mu m are greater than those suggested by simple theoretical relations. The high refractive index at this wavelength results in additional contributions to the transmitted intensity, most probably due to sample lensing effects arising from non-parallel sample faces or misalignment of the sample in the spectrophotometer beam.