FOCAS: The Faint Object Camera and Spectrograph for the Subaru Telescope

The Faint Object Camera and Spectrograph (FOCAS) is a Cassegrain optical instrument for the Subaru Telescope. Its capabilities include 6'phi FOV direct imaging, low-resolution spectroscopy (R = 250-2000 with 0.4 slitwidth), multi-slit spectroscopy and polarimetry. We describe the overall design of FOCAS, its observing functions, and the performance verification procedures that have been carried out.