Sub-Poisson statistics observed in an electronically shuttered and back-illuminated CCD pixel

The variance versus average signal has been measured for a pixel in an electronically shuttered and back-illuminated CCD imaging array. The measurements demonstrate that, over a certain operating range, the electronic shutter modifies the input Poisson distributed photoelectrons during the collection process such that the charge signal accumulated in the CCD well has a sub-Poisson distribution (variance less than the mean). A simple one-dimensional model has been developed that explains the experimental results.