Abstract

An apparatus designed and built to measure the infrared refractive index of an optical material as a function of wavelength and temperature is described. The values obtained for the thermal change in refractive index of a Si–As–Te glass, a Ge–Sb–Se glass, As₂S₂ glass, and Kodak Irtran 4 are presented. Treatment of these data and literature values for other ir optical materials from a molar refraction standpoint, were used to establish an empirical relationship for predicting unknown ΔN/ΔT°C values of new optical materials. Measured values range from +300 × 10⁻⁵/°C for covalent single crystal germanium to −235 × 10⁻⁶/°C for ionic polycrystalline KRS–5.

© 1967 Optical Society of America

Radiation-induced Changes in Refractive Index and Absorption Coefficient for Several Optical Materials

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