44
PG-200 Operation Manual
Version 2.D
Example 2
Laser (or other experimental equipment)
HV Gate Pulser
Controller
Trigger in
Inhibit
SHUTTER MONITOR (ST-130,
ST-133, ST-138, PentaMAX)
This mode of operation allows multiple laser pulses to be averaged (accumulated) on the
CCD. It is usually used with high repetition rate lasers or when S/N ratio considerations
require exposure of the CCD to many laser pulses before readout.
In this mode the controller is operated in the Freerun mode, and the laser is continuously
firing. SHUTTER MONITOR enables the pulser at the beginning of the CCD exposure
period. Each laser pulse then results in the ICCD being gated. Individual spectra (one
from each gate) are accumulated on the array until exposure is over and readout starts.
SHUTTER MONITOR then disables the pulser, preventing gating during CCD readout.
This is necessary to prevent excessive readout noise.
Since the laser fires at a rate higher than readout time, the sum of several firings will be
stored as a single frame. There will most likely be some variation in the intensity from
scan to scan. This is due to the laser operating asynchronously with the controller, which
implies that there can be a variation in the number of laser pulses occurring in each
exposure interval.
Figure 9.
System
configuration
for allowing
multiple laser
pulses to be
averaged on the
CCD.
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