UC Observatories Advanced Coatings Lab

(left) This is a silver-based coating produced for the Shane Adoptive Optics project in April 2013. It is on 7 mirrors in that system, which is currently in regular operation of Mt. Hamilton. This coating was designed to have high efficiency in the NIR, plus good reflectivity at the Na D line at 589 nm for use with the laser guide beacon. The recipe is seen below.

This coating withstood the 10-day 80/80 environmental test well. However, on stripping one OAP, we saw damage to the substrate, which we attributed to creation of HF from the thick layer of YF3 (see Phillips et al., 2014b). In subsequent runs, we replaced much (but not all) of the thick YF3 layer with SiO2 instead. The optical performance was completely comparable, as seen in the figure at left.

(left) This is a silver-based coating developed for the Keck Cosmic Web Imager (KCWI), currently under construction. This coating withstood the 10-day 80/80 environmental test well. Reflectivity pre- and post-environmental stressing is shown in the figure. The eventual coating on the mirrors was slightly modified and deposited at ZeCoat Corp., as some of the mirrors were too large for our chamber.