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Chapter 11: MCP Gating Option
In MCP Gating (not to be confused with MCP bracket pulsing,) the micro-channel plate
(MCP) is gated, and the photocathode gating brackets the high speed, 800 V, MCP gating
pulse. This technology allows fast gating (<10 ns) of the Super Blue (SB,) slow gate
intensifiers (typical gating speed ~ 200 ns) without sacrificing high QE.
The main limitations with this option are that there is a somewhat larger propagation delay
and larger optical FWHM than for a standard fast gate PI-MAX4. Insertion delay between
trigger and T0 is ~18 ns. Insertion delay to the photocathode gate is 30 ns. Insertion delay
to MCP gate is 80-205 ns, depending on the individual intensifier. This delay allows the
photocathode to be fully
ON before the MCP is gated. Pulse repetition rate is limited to
8kHz.
The PI-MAX4-MG camera uses a different High Voltage (HV)/Gating board than the
standard PI-MAX4 camera and is only available with Super Blue, slow gate intensifier
tubes.
NOTE:
The PI-MAX4-RF does not support picosecond gating.
Figure 11-1: Timing Diagram: Normal Gated Operation
Figure 11-2: Timing Diagram: MCP Bracket Pulsing Operation
Off Off
On
On
Photocathode Gating
MCP (Always ON)
4411-0137_0104
~10 ns
Off Off
Off Off
On
On
Photocathode Gating
MCP Bracket Pulsing
Gate Width
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