Dectris EIGER 2 - EIES - Externally Interrupted Exposure Series

After arming the detector, the acquisition can be enabled by an external signal. The value ntrigger denes how
often this can be repeated. The detector starts exposing the rst image after the rising edge and stops after the
falling edge of the external trigger signal. In the same manner, all subsequent frames are externally enabled.
The count time and period are therefore solely determined by the external enable signal and the limitations of
your detector system. The detector records as many frames as valid (according to the specications) enable
pulses are received until the value set for ntrigger is reached. Figure 9.4 illustrates a externally enabled series.
Time
ntrigger
1
2
3
- Enable Out
-
External In
Figure 9.4: Exposures dened by external enable
9.6. EIES - Externally Interrupted Exposure Series
Information #12
The externally interrupted trigger series is not available on the EIGER2 R 250K and EIGER2 R
500K detector systems.
In the externally interrupted trigger series (”eies”) mode, the rst trigger pulse will start the exposure and sub-
sequent triggers will stop the running exposure and start the next exposure with the smallest possible delay.
The last trigger, as congured in ntrigger will stop the running exposure and end the series. This mode is useful
when the exact length of an exposure is unknown and no gating signal is available.
It is possible to congure a number of skipped triggers which will be ignored. E.g. if {ntriggers_skipped: 2},
the rst trigger will start the exposure, the next two triggers will be ignored and the 4th trigger will stop the
running exposure and immediately start the next one and so forth. This cycle will continue until ntrigger has
been reached, where the skipped triggers are not counted. The number of trigger pulses to be sent for a full
series is (ntriggers_skipped+1)∗ (ntrigger−1)+1. The number of images acquired is always equal to ntrigger− 1.
Setting the count_time and frame_time as close to the expected real value is recommended to ensure the de-
tector count rate correction works optimally.
Information #13
To use this mode, the number of images nimages has to be set to 1 and the number of triggers
ntrigger has to be greater than 1. This has to be congured before changing to the eies mode. If
either of these conditions is not met, an error will be returned and the mode cannot be enabled.
Example detector conguration for externally interrupted exposure series:
detector | cong | nimages {”value”: 1}
DECTRIS EIGER
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