Zero Noise Wavefront Sensor Development within the Opticon European Network

This activity, funded by ESO and the European Commission through the Opticon Network will attempt to define, fabricate and fully characterize the best possible detector working at visible wavelengths suitable for wavefront sensors in Adaptive Optics (AO) systems. The detector will be a split frame transfer array built by e2v technologies and called CCD220. The frame rate will be very fast (up to 1.2 kHz) while the readout noise will be kept extremely low (typically below I e). The goal of this paper is to justify the choice of detector: an EMCCD with 240x240 pixels and 8 outputs that will provide sub-electron readout noise at 1-1.2 kHz frame rate. This paper shows that, despite the fact that EMCDDs have an excess noise factor of 1.4 due to the charge multiplication process; their virtually zero read noise should allow them to outperform the classical CCD. Such detectors do not yet exist and must be developed Moreover, this paper explains how the OPTICON European network is organized.