Submillimetre wave measurements of optical constants of water at various temperatures

Abstract

A polarization interferometer employing free standing wire grid polarizer and beamsplitter and reflection dispersive Fourier transform spectrometry are used to determine the optical constants of water in the region 5–220cm −1. The liquid cell uses a single crystal semiconductor or quartz window. The complex evaluation method first determines the optical constants of the window material and then takes into account all the interface contributions in terms of ‘complex insertion loss’ formalism and thus determines the precise values of optical constants of liquids. Power absorption coefficient and refractive index data of hyperpure silicon, and power absorption coefficient, refractive index and real and imaginary parts of complex relative permittivity data of liquid water at 4. 30 and 57°C are presented and discussed.