Instrument Calibration Information - ALOS_PRISM

The Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) is a panchromatic radiometer operating in the visible spectrum with 2.5m spatial resolution at nadir. Its extracted data provide a highly accurate digital surface model (DSM). PRISM has three independent optical systems for viewing nadir, forward and backward producing a stereoscopic image along the satellite's track. Each telescope consists of three mirrors and several CCD detectors for push-broom scanning. The nadir-viewing telescope covers a width of 70km; forward and backward telescopes cover 35km each. The telescopes are installed on the sides of the optical bench with precise temperature control. Forward and backward telescopes are inclined +24 and -24 degrees from nadir to realize a base-to-height ratio of 1.0. PRISM's wide field of view (FOV) provides three fully overlapped stereo (triplet) images of a 35km width without mechanical scanning or yaw steering of the satellite. Without this wide FOV, forward, nadir, and backward images would not overlap each other due to the Earth's rotation.