New Materials Applications in Solar Spectral Analysis

Abstract

The use of lithium niobate and liquid crystals in solar instrumentation designed for automatic measurement of spectral line shifts is described. A solid Fabry-Perot etalon of lithium niobate has an acceptance angle 5·3 times greater than an air-spaced Fabry-Perot filter for the same allowed passband broadening, and the lithium niobate device has no moving parts. The use of liquid crystals in Zeeman-effect analysers is also described. For a given phase retardation, liquid crystals require -1/1000 the voltage of solid crystals. They hold promise as reliable, long-lived variable retarders because they are free of the high-voltage breakdown problems of crystals such as potassium dideuterium phosphate (KDP). Progress toward implementation of devices with lithium niobate and liquid crystals in a solar telescope is described.