Cryogenic telescope, scanner, and imaging optics for the wide-field infrared survey explorer (WISE)

The Wide-field Infrared Survey Explorer (WISE) instrument includes a cryogenic telescope, scanner, and imaging optics module that provides four channels of infrared imaging between 2.8 and 26 microns. The telescope is a 40 cm aperture reflecting five-mirror imager/collimator relay that provides 8X demagnification, a 47 x 86 arcminute field of regard, and a real exit pupil for scanning. It also provides distortion control to better than one part in a thousand to prevent image blur during internal scanning. A one-axis scan mirror at the exit pupil scans the detectors' field-of-view across the telescope field-of-regard, countering the orbital motion and freezing the line of sight during the multi-second exposure period. The imaging optics module is a five-mirror re-imager with dichroic beamsplitters that separate the energy into four channels. All modules operate below 17 Kelvin. The all-reflective system uses aluminum mirrors and metering structures. The scanner is a derivative of the SPIRIT III scanner flown previously. WISE has been selected by NASA for Phase B design.