Characterization of a large-format charge-coupled device
Abstract
Characterization of a Kodak KAF 4200 CCD chip, coated with
the UV converter Lumigen, is described. This chip is very similar to a
chip described by Ninkov, Backer, and Bretz [Proc. SPIE 1987, 14
(1 993)], except for the Lumigen coating. The major difference in perlormance
is in the existence of significant deviations from linear output for
a given input up to 30% at low count rates. The nonlinearity varies across
the chip and is largest for pixels that are the most distant from the readout
serial register. Tests revealed that the nonlinearity depends on wavelength
in a minor way only, and is temperature dependent. Characterization
of the nonlinearity allowed the creation of a function that allows
for correction of the data. It is unlikely that this nonlinearity can be explained
using arguments invoking deferred charge effects or peculiar
behavior of the on-chip amplifier. Comparison with similar but uncoated
CCD chips makes the Lumigen coating a likely source of the problem.