Dynamic modulation transfer function measurement of image intensifiers using a narrow slit.

Modulation transfer function (MTF) is an important figure of image resolution of microchannel plate image intensifiers (MCPIIs). Dynamic MTFs of two Gen-II MCPIIs were measured under pulsed voltage operation (gated mode) using a narrow slit. The resolution determined by the MTF was calculated under various bias voltages and gate widths. Our numerical results show that with the increase of the reverse bias of MCPIIs, the resolution is improved rapidly below 40 V and then gradually decreased. With the MCP bias increased, both MCPIIs start to suffer rapid reductions in resolution at 800 and 750 V, respectively. The change of phosphor voltage has little influence on the resolution. The resolution declines rapidly with the decrease of the gate width below 20 ns but goes steady above 30 ns. We explored causes of these variations.