Spectrally-Quantified Chemical Reactivity of Optical Fluids and Materials in the GMACS Spectrograph for GMT

Abstract

We present a preview of compatibility tests for index-matching fluids with commonly used optical assembly materials. The optical coupling fluids used in the Giant Magellan Areal Camera and Spectrograph (GMACS) for the Giant Magellan Telescope (GMT) will be selected based on these empirical results. Although we focus on fluid candidates for GMACS, the results of the conducted experiments are applicable to all instruments that use optical index-matching fluids. The experiment presented here identifies potentially corrosive matchings of fluids and materials. In the experiment, a material (RTV, polyethylene, delrin, etc.) is submerged in a quartz cuvette of fluid (Cargille liquids, glycerin, etc.). Contamination is observed by using a spectrometer to measure the absorption spectrum at various post-submersion times. The final results will track the percent degradation in the UV transmission as a function of post-submersion time. The final paper will be presented at SPIE conference 8446.