Abstract

We will briefly describe the Hubble Space Telescope Faint Object Camera (FOC) and its operation, and the problems and solutions in calibrating it. The FOC is a photon counting imaging system with two different detectors in two different optical relays capable of f/96, f/288, or f/48 mode imaging, the last mode having a long slit spectrograph capability also (Ref. ¹). The detectors (shown schematically in Figure 1), by and large the source of calibration difficulties, detect and store photons by using a three stage image intensifier with bialkalii photocathodes coupled with a television tube followed by signal processing electronics to recognize photon events. As photon events are recognized, they are stored in a digital memory which accumulates the image. The detector is capable of imaging sections of the focal plane photocathode in a wide variety of sizes and offsets (referred to as video formats). The largest has dimensions of 512 by 1024 pixels and covers a 44” by 44” area of the sky (f/48 relay).

© 1988 Optical Society of America