Materials for optical coatings in the ultraviolet

Abstract

In this work, we used 248-nm 20-nsec laser pulses to measure laser-damage thresholds for halfwave-thick single layers of fifteen potential UV coating materials, for highly reflective coatings made of thirteen combinations of these materials, and for antireflective coatings made using five combinations of the materials. Refractive index, absorption, position of the UV absorption edge, stress, and environmental stability were measured for the halfwave-thick single layers. The first three of these parameters are closely related and were generally correlated with damage thresholds of the single-layer coatings. Thresholds of HR coatings were correlated with absorption in the high-index materials used in the coatings and with refractive index of the low-index materials. Thresholds of AR films were not well correlated with properties of single-layer coatings.