Thermoelastic-damping noise from sapphire mirrors in a fundamental-noise-limited interferometer.

We report the first high-precision interferometer using large sapphire mirrors, and we present the first direct, broadband measurements of the fundamental thermal noise in these mirrors. Our results agree well with the thermoelastic-damping noise predictions of Braginsky, et al. and Cerdonio et al., which have been used to predict the astrophysical reach of advanced interferometric gravitational wave detectors.