An intensified C.C.D. camera for telescope guidance

Abstract

This paper deals with the study and the fabrication of an intensified C.C.D. camera for guiding telescopes or for searching fields containing faint stars. It describes the sensor of the camera (by connecting the Thomson C.C.D. and the RTC image intensifier) and its three working modes. The first is the direct exploitation of the video signal sent to the TV monitor, in conformity with the C.C.I.R. standard (the N.T.S.C. standard is also available). However, the study of stability and sensitivity of the intensifier lead us to create a second working mode necessary for the correct detection of faint objects (by an “averaging filter” improving the signal to noise ratio). The last mode is the “integration” by the C.C.D. itself: it allows a maximum of three-seconds integration time (therefore the detection of fainter objects), with the help of a thermoelectric cooling system. Moreover, the tests made on the 1.52 meter telescope of the O.A.N. (Calar-Alto, Spain) have been successful and confirm the capabilities of this camera to replace the intensified TV tube cameras, like the super-isocon camera.