The Integrated Beam Control Demonstration (IBCD) brassboard for the Advanced Beam Control System (ABCS) rapidly directs a laser beam over a wide field of view with high precision. The pointing control system consists of four fast steering mirrors and a visible- wavelength alignment sensor, coordinated by a central computer. This paper describes the IBCD pointing control system requirements and it design, and presents the results of recent performance tests.
The three Fine Guidance Sensors (FGS's) on board the Hubble Space Telescope have been operated extensively since the observatory was launched in April, 1990. The FGS's, each capable of measuring angle as small as 0.003 arc-seconds (15 nanoradians), provide required fine pointing information to the Space Telescope's pointing control system, and are intended to serve as astrometry instruments. On-orbit data have shown that the acquisition, pointing and tracking performance of the FGS's in most cases meets, and of these sometimes exceeds, requirements. The versatility of the FGS digital control electronics to adapt to the unexpected conditions imposed on the sensors by the telescope spherical aberration and by solar panel jitter will be discussed. There is encouragement from both on-orbit tests and analytical studies that the FGS's can accommodate the current telescope characteristics. Improvements to guide star acquisitions within the FGS's and to target acquisitions within science instruments have been accomplished with the internal distortion calibration of each FGS and with the alignment calibration between sensors. Techniques used in the calibration process and the resulting improvements in acquisitions will be presented.
The development of the Integrated Beam Control Demonstration (IBCD) brassboard for the Advanced Beam Control System (ABCS) program requires high speed large angle steering mirrors for internal laser beam control. These mirrors, which use large dynamic range voice- coil actuators and position sensor for steering and precision pointing, must be able to steer through a significant fraction of a radian in two axes and operate at a high bandwidth. Hughes Danbury Optical Systems, Inc., has successfully designed, fabricated, and tested these large angle fast steering mirrors. This paper presents some of the measurement data acquired during the recently concluded performance testing.