Photoelastic modulator for the 055–13-μm range

An improved photoelastic modulator (PEM) employing two piezoelectric transducers and incorporating a new ir zmc selenide (ZnSe) optical element is described. The 0.64-cm thick PEM is capable of obtaining quarter-wave retardation from 0.55 microm to 13.0 microm. Previously no single, high quality, low static strain PEM element existed for this wavelength range. We have also constructed other PEM's using optical elements composed of fused quartz, calcium fluoride, and KRS-5. The important optical and mechanical properties are measured and compared.