WFPC2 Instrument Science Report 92-05 (11/92):
Summary of WFPC2 AFM and POMM Actuation Algorithm
by C. Burrows
Abstract excerpted from the Report:
This note is to summarize part of the algorithms to be implemented in the ground system in order to control the WFPC2 actuated fold and pickoff mirrors. Each AFM actuator consists of two independently commandable segments, each camera has three actuators arranged roughly in an equilateral triangle, and there are three cameras with AFM. The actuators are arranged and numbered in a manner that rotates by 90 degrees between adjacent cameras, so that the nominal conversion of AFM tilt in detector coordinates (CCD rows and columns projected back optically to the AFM) is the same in all cameras. The one pick-off mirror mechanism is controlled around two axes of tilt, and the transformation of this tilt to the detector frame is dependen on the camera in use. Commanding for the pickoff mirror is dicussed separately at the end of this note.
The Complete Paper is now available, (Post Script, 8.5 Mbytes).