Miniature imaging photon detectors. III. An assessment of the performance of the resistive anode IPD

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Abstract
For pt.II see ibid., vol.13, p.763 (1980). The imaging performance of a proximity-focused imaging photon detector using microchannel plate (MCP) intensifiers, and a resistive anode is determined by four major factors. These are: the electron optics of the biplanar lens formed by the photocathode and MCP, with a gap of between 300 mu m and 1 mm; the random walk process of intensification within a triple-MCP (Z-plate) intensifier; the noise factor of the anode and the preamplifiers, and the errors of the main signal processing electronics. A device with a 1.0 mm photocathode to MCP gap and a potential difference of about 250V across this gap, and a 'linear' resistive anode read-out system, shows a point spread function with a full width half maximum (FWHM) of 86 mu m. Consideration of the potential improvements which would materially affect resolution indicate that about 30 mu m FWHM is achievable, corresponding to a limiting resolution of 34 line pairs per mm, at 3% modulation.