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High-Speed Gating Of Image Intensifiers With Proximity Focus

Proximity-focus image intensifiers of the diode type or with microchannel plate may be used for high speed photography even in the subnanosecond range. For high speed gating the conductivity of the photocathode has to be greatly increased by a conductive layer. Additionally the connection of the image intensifier with the gating-impulse generator requires special measures. The behaviour of the gated image intensifier can be simulated using a simplified transmission line equation. Thereby all the parameters influencing the gating behaviour can be evaluated. All measures which are increasing the gating capability, that are increase of the cathode conductivity, reduction of the optically active cathode area, and increase of the electrode distance, also affect other parameters in a disadvantageous way. Thus a compromise between the different requirements is necessary. Exposure times even in the sub-nanosecond range are possible. The experimental evaluation of the exposure time generally can be done by measurements of the temporal behaviour of the luminous screen. In the subnanosecond range, however, this may require other methods due to lack of extremely fast photo-multipliers.