Specifications

Version 1.1 rev Jan 2013
Page 67
iXon Ultra
, Features and Functionality
3.5.1.2 - External Triggering (FT)
When the camera is idle, it runs the Idle Keep Clean Cycle described previously. On receipt of the Start command
from the PC, the camera goes into its External Keep Clean Cycle. This cycle consists of one vertical followed by one
horizontal shift, repeated continuously. The camera repeats this cycle X times, where X is the number of image rows
on the sensor, before it accepts any External Trigger events. Once this period is over, the camera continues running the
External Keep Clean Cycle until an External Trigger is received. At that point the current External Keep Clean Cycle is
complete, and the camera stops all vertical clocking and waits for the programmed user delay period before starting the
read phase. During the readout phase the Image area is transferred rapidly to the Storage area. The Storage area is
then read out in the normal way.
Once the readout is complete the camera continues to wait for the next external trigger event. While the camera is
waiting for the trigger event, the shift register is continually clocked but the Image and Storage areas are not. On the
next trigger the camera again waits for the programmed delay before starting the readout phase. The camera continues
in this cycle until the number of images requested are captured. Because the Image area is not cleaned between trigger
events, the effective exposure time is the time between events. The User Dened Delay is to allow for the capture of
events which occur after the trigger pulse. In the case of the rst trigger, the effective exposure time is given by the User
Dened Delay since Keep Clean Cycles have been running up until the rst trigger. This is in contrast to the subsequent
exposure periods which are dened the time between the external trigger events. Thus, for experimental protocols
that involve Continuous Wave (CW) light the rst image will be dimmer; some protocols may require that this image is
discarded.
Figure 25: External Trigger in Frame Transfer mode