The resolution of microchannel-plate image intensifiers (MCPIIs), when specified by manufacturers, is usually only measured while the MCPII is biased on with dc voltages (dc mode). We present data on the resolution of two proximity focused MCPIIs under both dc bias and pulsed voltage operation (gated mode). The resolution is determined by recording a digital image of the MCPII's output for an input in the form of a spatial impulse. By calculating the Fourier transform of the two-dimensional output images distribution (the output point spread function), the modulation transfer function can be found. The effects of input optical energy density, gate repetition rate, gate width, and input position on the resolution of a standard ITT MCPII and a high strip current ITT MCPII are studied.
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