A novel high resolution, high frame rate detector based on a microchannel plate read out with the Medipix2 counting CMOS pixel chip

The future of ground-based optical astronomy lies with advancements in adaptive optics (AO) to overcome the limitations that the atmosphere places on high resolution imaging. A key technology for AO systems on future very large telescopes are the wavefront sensors (WFS) which detect the optical phase error and send corrections to deformable mirrors. Telescopes with >30 m diameters will require WFS detectors that have large pixel formats (512/spl times/512), low noise (<3 e/sup -//pixel) and very high frame rates (/spl sim/1 kHz). These requirements have led to the idea of a bare CMOS active pixel device (the Medipix2 chip) functioning in counting mode as an anode with noiseless readout for a microchannel plate (MCP) detector. First measurement results obtained with this novel detector are presented both for UV photons and beta particles.