Building a Cookbook 245 CCD Camera

Building a Cookbook 245 CCD camera based on the design by R. Berry, V. Kanto, and J. Munger was the essence of the honors thesis for Nick Kalayjian '95. This camera was designed primarily as an autoguider for the 20 inch telescope in the Olin Observatory, but we also had need occasionally for an additional imaging camera. The constraints of imaging guided most of our design choices.

We chose to build the TI245 system because of lower read noise and the larger imaging-area size. The binned pixel size of 25.5 X 19.7 microns for our C8 finder 'scope resulted in reasonable sampling (1.4 arcsec/pixel) over a typical stellar seeing disk of ~ 4 arcseconds.

Modifications to the basic camera design included a metal case for the power supply, fancier switches, higher quality connectors, switching the Peltier and pump together, using a self-priming bilge pump for coolant handling, and enclosing the imaging array in a vacuum-sealed head. This last design choice eliminates frosting of the chip, and gains us a few degrees in the chamber temperature by removing the cold finger.

The design of the vacuum camera head required a value to be added to the camera head wall as well as vacuum feed-throughs for future temerature monitoring sensors on the chip. The values now used are a medical value, luer lock, which are very inexpensive, but will hold a vacuum of roughly a few hundreths of an atmosphere for a week or more, enough to eliminate frosting. O rings were added to the chamber faces and Torr Seal (vacuum safe epoxy) was used through out. A thicker optical window was introduced (~ 3 mm) to handle the additional force. The whole system is pumped down with a hand pump typically used for student optical interference experiments.

Future changes and upgrades include building the autoguider io card, adding a chip temperature sensor, anodizing the draw tube, switching to an AR coated optical window, and possibly changing the type of vacuum value used.

Nick and the Camera

...Camera Power Supply ...CCD Chip Vacuum Housing/Head and Preamp

...Interface Board

Images Taken With This Camera

Nick is now off to graduate school at Stanford in Mechanical Engineering. As soon as the semester begins he should have an e-mail address.