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Proceedings Paper

The CFHT CCD Detector
Author(s): G. A.H. Walker; R. Johnson; Carol A. Christian; Patrick Waddell; J. Kormendy
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Paper Abstract

The CCD is a thinned, rear-illuminated, RCA device with 320 rows and 512 columns of which about 316 x498 are photometrically useable. The array is over-clocked by the equivalent of 20 extra rows to provide a d.c. bias reference. The array has exceptionally high spectral band width and responsive quantum efficiency and operates in an evacuated cold housing in an analog integration mode at -125°C. On-chip amplifier 'glow' has been limited by reducing drain voltages during integration. The average system read-out noise/sensing element (pixel) is 71 electrons rms. The system response is linear from about 300 electrons to the full-well potential of 6 x105 electrons. There is a significant roll-off in charge transfer efficiency at low signal levels which is probably due to non-overlapping of the gate-electrode structure. (Not a problem with more recent versions of this device). The transfer efficiency was optimized by increasing the overlap and the amplitude of the clock transitions. About 30 pixels have low sensitivity and one third act as 'traps' by attenuating subsequent charge transfers from their column. A few pixels 'glow' causing signal saturation around them. The CCD can be calibrated with a pixel to pixel reliability over the whole array of 2% using illumination of the dome interior as a flat field and to <1% using dark fields in the night sky. Optical fringing from night sky lines is not important in B and V, and can probably be calibrated at longer wavelengths.

Paper Details

Date Published: 8 November 1984
PDF: 6 pages
Proc. SPIE 0501, State-of-the-Art Imaging Arrays and Their Applications, (8 November 1984); doi: 10.1117/12.944681
Show Author Affiliations
G. A.H. Walker, University of British Columbia (Canada)
R. Johnson, University of British Columbia (Canada)
Carol A. Christian, University of Hawaii (Canada)
Patrick Waddell, University of Hawaii (Canada)
J. Kormendy, Dominion Astrophysical Observatory (Canada)

Published in SPIE Proceedings Vol. 0501:
State-of-the-Art Imaging Arrays and Their Applications
Keith N. Prettyjohns, Editor(s)

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