Nanosecond-gating properties of proximity-focused microchannel-plate image intensifiers

Some fundamental properties of 18 mm-diam gated proximity focussed microchannel plate (MCP) image intensifiers used as fast image shutters in the 1 to 10 ns range were identified and studied. Light pulses from a modelocked dye laser optically sample the gated MCP. Shuttering is achieved by applying a forward biasing electrical gate pulse to the quiescently reverse-biased photocathode MCP interface. Variable delay between the gate pulse and the laser pulse permits tracing the MCP's optical response. Gating speeds, turn-on and turn-off patterns, the asymmetric spatial depedence of the MCP optical response, and resolution effects as functions of gate pulse width and photocathode-MCP bias were characterized. Variations in the intensity profiles of the phosphor's spatial response for uniform photocathode illumination are measured with a calibrated silicon intensified target focus projection, scan television camera and a high speed video digitizer while photomultipliers monitor the laser pulse and the phosphor's spatially integrated output intensities.