Scanning imaging absorption spectrometer for atmospheric chartography (SCIAMACHY) is an optical imaging spectrometer for atmospheric chemistry research. The instrument is selected by ESA for the Polar Platform mission. The optical system of SCIAMACHY consists of scanning mirrors, a telescope, and a complex spectrometer system. With the scanning mirrors the instrument can be directed in nadir or limb direction. The FOV is 2.3 X 0.023 degrees. With the spectrometer high spectral resolution (0.2 nm) measurements are simultaneously performed over a wide spectral range (0.24 to 2.4 micrometers ). Besides the polarization of the incoming radiation is measured with a polarization measurement device. For inflight calibration various possibilities are foreseen such as sun, moon, and on-board light sources.