Mosaic CCD camera system Implemetation and Application to Astronomical imaging; a thesis submitted for the degree of philosophy in Bangalore Universtiy, Bangalore B. Nagaraj Naidu [Ph.D Thesis]

Doctor of Philosophy Bangalore University , Bangalore 2001

Mosaic CCDs are particularly useful in imaging large size celestial objects like open clusters, globular clusters, galaxies etc. In such studies, a wide field coverage in a single observation run reduces the observation time at telescopes which otherwise might have required as many observational runs as the number of individual CCDs in the mosaic configuration.Imaging with mosaic CCDs has received considerable attention in the past few years following the availability of buttable CCDs and fast Digital Signal
Processors (OSPs). The advent of computer technology in hardware and software has given a scope for the development of powerful general-purpose CCD camera controllers. The OSPs offer flexibility, configurability and high-speed data
acquisition needed for building such camera controllers. While the clock generation and data acquisition functions are met by a front end DSP, large data storage, powerful graphics display and processing functions are best handled by a host like Pentium PC. Such general purpose camera controllers which can operate mosaic CCDs are not available commercially. As a next step to the mosaic controllers specifically developed for a specific research needs, it is considered appropriate to develop a general purpose controller which can easily be programmed to suit any CCO or combination of such CCDs. Usually any
hardware change in the camera such as that of a CCD chip to suit specific imaging requirement results in a corresponding change in the controller which imposes long lead time in the development phase. A software approach in such a situation ensures a reduction in the development and turn-around time. The host interface itself can easily accommodate the changes through its application software. Keeping these factors in view, a general-purpose flexible CCD camera Controller which can address any CCD or mosaic CCDs has been developed at the Indian Institute of Astrophysics (IIA). The primary design goals that need to be
met can be summarized as follows.

I. A flexible, modular and re-configurable controller which meets various Requirements in a simple way.

2. A powerful front-end controller which controls the camera controller functions and a host interface which provides a state of the art graphical user Interface, data acquisition, display and data reduction functions.
3. A loss-less on-line data compression resulting in reduction in data storage and Band width required for transmission.
4. A controller configurable for remote operation.
5. Provide an integrated environment with distributed computers implementing
various other functions such as telescope control, dome control, back-end
instrument control etc.

During this thesis work, a general purpose CCD camera controller based on a DSP has been successfully built and configured for a mosaic of 2x2 3-edge Buttable Thomson-CSF CCDs (THX7897M). The controller operates from an IBM environment with a custom-built host interface add-on card. The controller was also successfully configured and tested with two other CCD: the ST002AB (2Kx4K) and the SI424 (2Kx2K). A modular CCO cryostats has been developed to accommodate the 2x2 THX7897M mosaic CCDs, the ST002AB and the SI424 CCDs. CCO data acquisition and display software has been developed under
Windows9X/NT environment to support the above CCO camera systems