The TEDI project involved building an EDI interferometer to fit inside the Cassegrain output hole of the Mt. Palomar 200 inch telescope to demonstrate a novel technique for a Doppler planet search in the near infrared (0.9-2.5 micron), for planets around cool stars, which are the majority star type. Instead of measuring Doppler wavelength shifts with a spectrograph alone, which requires a very high resolution spectrograph, the shifts were observed in fringes in a small interferometer. The EDI technique enabled the spectrograph to be of lower resolution and smaller size. Since the spectrograph is usually the largest and most expensive component of the system, it allowed the whole instrument to be 10x or more compact.
