A New Digital CCD Readout Technique for Ultra–Low‐Noise CCDs

We present a completely new technique to read out the CCD matrix that can achieve much lower noise than classical techniques used since the 1970s. This technique is based on digital analysis of the CCD's output signal instead of analog filtering coupled to an original filtering method. Despite several attempts carried out in the past to implement digital correlated double sampling, this is the first time that a radical improvement in readout noise performance is shown. This is highly interesting for low light level conditions, where the detector works in the readout‐noise regime and not in the photon‐noise regime. This is particularly the case when carrying out medium‐ to high‐resolution spectroscopy or multiplex (scanning) observations.