Portal de Periódicos da CAPES

Optically sensitive Medipix2 detector for adaptive optics wavefront sensing

2005; Elsevier BV; Volume: 546; Issue: 1-2 Linguagem: Inglês

10.1016/j.nima.2005.03.102

1872-9576

John V. Vallerga, Jason B. McPhate, Anton S. Tremsin, Oswald H. W. Siegmund, Bettina Mikulec, A. Clark,

Photocathodes and Microchannel Plates

A new hybrid optical detector is described that has many of the attributes desired for the next generation adaptive optics (AO) wavefront sensors. The detector consists of a proximity focused microchannel plate (MCP) read out by multi-pixel application specific integrated circuit (ASIC) chips developed at CERN (“Medipix2”) with individual pixels that amplify, discriminate and count input events. The detector has 256×256 pixels, zero readout noise (photon counting), can be read out at 1 kHz frame rates and is abutable on 3 sides. The Medipix2 readout chips can be electronically shuttered down to a temporal window of a few microseconds with an accuracy of 10 ns. When used in a Shack–Hartmann style wavefront sensor, a detector with 4 Medipix chips should be able to centroid approximately 5000 spots using 7×7 pixel sub-apertures resulting in very linear, off-null error correction terms. The quantum efficiency depends on the optical photocathode chosen for the bandpass of interest.