Clearing a CCD

[ALAIN MAURY <maury@ocar01.obs-azur.fr>]

This is our procedure to erase the CCD:
If I remember well:
We use a fast horizontal shift mode, which does not run the
acquisition chain ( sample and hold, A/D converter ), and since
the horizontal register has about quadruple the capacity ( full well )
as the vertical one, we typically readout the chip 3 times ( or
about 6000 vetical shift ), and between each vertical shift we do
about one third of the horizontal register. This erases the chip
in a few seconds.
There are faster way to do it, in some old CCDs you were able to
bring the substrate voltage higher than the cloks and this would
erase the ccd instantly.
There are different ways to do it, but usually erasing the CCD
takes a few seconds, even for large CCDs.
Alain