73
Chapter 6
Shutter Mode Operation
Introduction
Shutter Mode is the simplest PI-MAX intensifier operating mode and, as in Chapter 4, can
be used to verify initial operation and to focus the camera and/or spectrograph. In Shutter
Mode operation, intensifier gating is under the control of signals from the ST-133. These
signals are applied to the PI-MAX via the cable connected to the Power/Signal connector.
Their generation and timing are under software control and the ST-133 treats the
photocathode as if it were a mechanical shutter. With the exception of the Internal Sync
(PTG) timing mode, the photocathode is held biased ON during the selected exposure time,
allowing the PI-MAX to see light continuously during that time, and is biased OFF for the
readout period.
Note: No timing generator is needed for Shutter Mode operation.
Cabling
With the exception of the Internal Sync (PTG) timing mode, a timing generator is not
used in Shutter Mode operation.
If a PTG is installed in the ST-133, older systems require that cable to the PI-MAX's
Timing Gen. connector be disconnected; newer systems ignore the connector when
Shutter Mode is being used.
If a DG535 is cabled to the PI-MAX and the ST-133, the DG535 should be powered
down or the cables to the ST-133 Ext. Sync connector and to the PI-MAX's Timing
Gen. connector should be disconnected.
Shutter Control
Since the ST-133 is gating the photocathode on and off as if it were a mechanical shutter,
you have the choice of Normal and PreOpen "shutter" settings. Normal is available for
the Free Run and External Sync timing modes. PreOpen is only available for the
External Sync modes and Internal Sync for PTG.
Normal: The photocathode is biased on and off in synchronism with system timing.
With External Sync and External Sync with Continuous Cleans modes, photocathode
gating is controlled by the External Sync pulse. The ST-133 waits for the pulse and
then gates the photocathode on for the set exposure time. As soon as the exposure is
complete, the photocathode is biased off, the shutter compensation time elapses, and
the array is read out.
PreOpen: Available in the External Sync and External Sync with Continuous Cleans
modes, photocathode gating is only partially synchronized to the experiment. The
photocathode is gated on as soon as the ST-133 is ready to receive an External Sync
pulse. When the External Sync pulse arrives at the Ext Sync input, the photocathode
remains on until the end of the set exposure time, the photocathode is biased off, the
To Next Page
Loading...
