Hamamatsu Photonics C10910, Инструкция по эксплуатации, Страница: 66 / 105

C10910 INSTRUCTION MANUAL Ver.1.19E
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(2) GATE
This mode is only selectable when using a single sweep unit (cannot be selected on
the synchroscan unit). In GATE mode, the streak tube operates only during the
sweep period. This prevents a rise in background noise which is caused by the
incident light outside the measurement period and also by dark current, allowing
measurement with a good S/N ratio. This operation is shown in the timing chart
below.
The gate opens on the rising edge of a pulse input via the GATE TRIG IN connector.
Then, when a sweep is performed, the gate closes by automatically detecting the end
of the sweep. To ensure high precision measurement, the trigger input timing must be
adjusted so that the gate only opens during the valid streak sweep. The gate settles
to a sufficiently stable value some 300 ns after the trigger signal is input. If a sweep
occurred before the signal is stabilized, then the streak image might darken or
defocus, so be careful when setting this timing.
Shortening the time period from the gate trigger input to the sweep trigger input as
much as possible in a range longer than 300 ns will usually obtain good results due to
the lower noise and dark current.
Gate status
Sweep trigger
Sweep waveform
Monitor Out
OPEN CLOSE
About 300 ns(gate opening time after gate trigger input)
Gate trigger
> 300 ns (input after gate opened)
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