DIMM: A Differential Image Motion Monitor for CFHT
M. Baril, B. Mahoney, T. Benedict, K. Ho, D. Salmon

Abstract: The DIMM is a differential image motion monitor that will provide seeing estimates in real time from the slit opening of the CFHT dome. The DIMM consists of a 14 aperture F-10 Schmidt-Cassegrain telescope, Meade LX200 GPS, on which is mounted two SBIG ST-7XMEI CCD cameras, Kodak KAF-402ME, 796 x 512 sensor. Two prisms are mounted in the telescope aperture to provide offset images of the monitor star at the prime focus so that tip-tilt of the wavefront can be determined. The Meade telescope is currently undergoing major hardware and software modifications in order to improve reliability and to achieve the necessary tracking requirements. Sky tests of the basic operation of the system are expected to be initiated in the beginning of May 2007.