This paper presents the development of the IASI Infrared Spot Scan test equipment, with a focus on the mechanical design. The IASI instrument, developed by Alcatel, is a spaceborne meteorological instrument, for observation of the Earth atmosphere in the infrared wavelength region. An infrared Optical Ground Support Equipment (OGSE), developed by TNO TPD is used to test the focal plane of the IASI instrument. The characterization is done by response
measurement of an infrared spot scanning the detector area of IASI. The vacuum part of the OGSE consists of 3 linear stages, an optical table comprising an infrared source, an elliptical mirror, a shutter and a diaphragm. The system is partly cooled. A control system for stages, shutter and thermal control completes the system.