<title>Photon-counting optical detectors with high spatial and temporal resolution</title>

Abstract

Image intensification systems have been used for photon counting applications in ground based and space based astronomy for many years. Various charge amplification and image readout techniques have been used, but some of the most successful to date utilize the microchannel plate (MCP) intensifier in a 'Gen II' configuration with an electronic image sensor. The two major competitive solutions for image sensor are the CCD, which reads the optical image from a phosphor, and the electronic image readout, which collects the charge from the MCP directly, replacing the phosphor. We describe the advantages of the electronic charge division image readout and compare its performance with other imaging techniques. For example, intensifiers using charge division readouts have distinct advantages over intensified CCDs for applications where localized count rate capability (point source count rate) and temporal resolution (event time tagging accuracy) are important. We discuss existing and potential astronomical applications for these detector systems. We discuss recent improvements in imaging performance obtained with charge division readouts, comparing the performance of traditional resistive anode readouts with the latest generation of pattern designs including the Vernier anode. We present results showing the imaging performance of the Vernier anode. We describe a photon counting imaging intensifier system for ground and space based applications in astronomy. The intensifier, which is manufactured by Photek Ltd., uses a proximity focused photocathode, microchannel plate intensifier and conductive charge division electronic readout. A variety of pattern designs offer performance ranging up to 4000 X 4000 pixel format, with position resolution down to 10 microns FWHM and sub-microsecond timing accuracy.