Descr: MRO will be building a 10 telescope optical interferometer using 1.4 meter telescopes with baselines of up to 400 meters on Magdalena Ridge at an elevation of approximately 10,580 feet (3324 meters). The path lengths between any pair of telescopes must be actively maintained to a fraction of the wavelength of light that we are using. We will be working in the Visual to Near Infrared wavelength range (600 nm to 2200 nm). We would like to measure the ground motion both amplitude and frequency up to 500 Hz.