CHARACTERIZATION OF A LARGE-FORMAT CHARGE-COUPLED-DEVICE

Characterization of a Kodak KAF 4200 CCD chip, coated with the UV conv erter Lumigen, is described. This chip is very similar to a chip descr ibed by Ninkov, Backer, and Bretz [Proc. SPIE 1987, 14 (1993)], except for the Lumigen coating. The major difference in performance is in th e existence of significant deviations from linear output for a given i nput 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 read out serial register. Tests revealed that the nonlinearity depends on w avelength in a minor way only, and is temperature dependent. Character ization of the nonlinearity allowed the creation of a function that al lows 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 bu t uncoated CCD chips makes the Lumigen coating a likely source of the problem.