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Chapter 12: Picosecond Gating Option
The picosecond gating option for the PI-MAX4 allows optical gates down to less than
500 ps or to the lowest gate width the intensifier will support, whichever is greater. It
consists of a picosecond gating board installed in the PI-MAX4 and some other
modifications to support the board. The picosecond option can operate up to 100 kHz
repetition rate
1
(the main gate generator goes to 1 MHz) and has a few nanoseconds larger
insertion delay than the main gate generator. The
MONITOR BNC output operates
differently in picosecond operation.
NOTE:
The PI-MAX4-RF does not support picosecond gating.
12.1 Activating Picosecond Operation
WinX: Automatically selects the picosecond gating board whenever the gate width is set
below 3 ns.
LightField: The Picosecond Widths button is added to the
SuperSYNCHRO Timing expander when a PI-MAX4 containing the picosecond gating
board is detected and loaded as an experiment device.
12.2 Gain and Gate Width
The apparent gain of the intensifier falls off as the gate width is reduced. Typically, at the
lower limit, the gain is less than 10% of the value observed at 50 ns.
•WinX
The software automatically selects the appropriate gate pulse generator to use when
the user selects a gate width: the standard switch-over width is 3 ns.
• LightField
The user selects one of the available gate widths from the Picosecond Widths drop
down list and that width will be automatically entered in the
Gate Width field(s.)
NOTE:
When Sequential Gating is active, the starting and ending gate
widths are the same - there are
NO gate width sequences.
However, different starting and ending gate delays (swept
delay) can be used with a constant gate width.
1. Refer to Section 12.4, Repetition Rate Issues, for additional information about achievable repetition rates.