Princeton Instruments ProEM+ EMCCD, User Manual

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Chapter 6 Advanced Topics 85
85
LOGIC OUT Control
The TTL-compatible logic level output (0 to +3.3 V) from the LOGIC OUT connector
on the rear panel can be used to monitor camera status and control external devices. By
default, the logic output level is high while the action is occurring. The timing of the
level changes depends on the output type selected on the
Hardware
Setup|Controller/Camera tab { Trigger expander}. The available logic levels are
camera dependent. The possible levels are:
 Acquiring {Acquiring}: After a start acquisition command, this output changes
state on completion of the array cleaning cycles that precede the first exposure.
Initially low, it goes high to mark the beginning of the first exposure. In free run
operation it remains high until the system is halted. If a specific number of
frames have been programmed, it remains high until all have been taken and then
returns low. Figure 47 assumes 3 frames have been programmed.

Expose (Effective) {Effectively Exposing}: This level is at a logic high during
the effective exposure time. This exposure time equals the read out time in frame
transfer mode when the exposure time is less than the readout time. Otherwise,
Expose (Effective) and Expose (Program’d) are identical.

Expose (Program’d) {Exposing}:
This level is at a logic high during the
programmed exposure time (i.e., the time set in the software).

Image Shift {Shifting Under Mask}: This level is at a logic high while the
image is being shifted under the mask.

Logic 1 {Always High}: The level at the connector is high.

Read Out {Reading Out}: It is at a logic high when CCD is being read;
otherwise low.

Shutter {Shutter Open}: This level is at a logic high when the shutter is open.
The output precisely brackets shutter-open time (exclusive of shutter open
compensation, t
c
) and can be used to control an external shutter or to inhibit a
pulser or timing generator.

Wait for Trigger {Waiting For Trigger}: This level is at a logic high when the
camera is ready to acquire and is waiting for an external trigger (through the EXT
SYNC connector) before exposing the CCD. The level goes low when a trigger is
detected: exposure begins. The Wait for Trigger (WFT) signal goes high
immediately after readout or after Preopen {Open Before Trigger}(if it is active).
If continuous cleans is enabled, the camera will check for a trigger at the EXT
SYNC connector before entering a continuous clean cycle. If none has occurred,
a cleaning cycle is initiated and completed. Before the next cycle begins, the
EXT SYNC connector is checked again, and exposure will start if a trigger has
occurred.