Theoretical and Experimental Investigation of Gating Performance of Subnanosecond Image Intensifier With Microstrip Photocathode

Abstract

We have studied the transmission performance of gating pulses on the microstrip photocathode (PC) of an ultrafast image intensifier. A numerical calculation model that included the impedance mismatch between the strip PC and the input line was established to simulate gating pulse propagation. The transmission performances of the pulses were investigated using simulations and experimental evaluations of several factors that affect transmission, including the PC-to-microchannel plate (MCP) input spacing, the PC resistance, the input pulsewidth, and the photocurrent. In addition, some of the simulation results were validated experimentally. The research produced the following results: 1) accumulation among the transmitted and reflected pulses is a major factor in broadening the width of the gating pulse; 2) reduction of the PC-to-MCP input spacing and a slight increase in direct current resistance can improve the gating speed and reduce the delay between the input and output ends; 3) when the input pulsewidth is more than 500 ps, the width of the transmitted pulse on the PC is almost equal to that of the input pulse, and amplitude attenuation is almost constant; and 4) the minimum gating time that can be achieved using this device was approximately 420 ps. Finally, preliminary testing of the optical gating time was implemented. The experimental results showed that when an input pulse with a full width of 0.8 ns was superimposed on the strip PC, the image intensifier could achieve an optical gating time of 0.7 ns.