Andor Technology iXon3 Series - Triggering Options in Frame Transfer (FT) Mode; Internal (FT)

Page 42
iXon 3
Section Title
3.5.1 - Triggering options in Frame Transfer (FT) mode
3.5.1.1 - Internal (FT)
This is the simplest mode of operation in that the camera determines when the exposure happens. By monitoring the
FIREoutputtheusercandetermineexactlywhenthecamerais“exposing”.
When the camera is idle, it is running the Idle Keep Clean Cycledescribedpreviously.OnreceiptoftheStartcommand
from the PC, the camera will complete the current keep clean cycle and then perform sufcient vertical shifts to ensure
that the Image and Storage regions are completely free of charge. The camera then starts its real exposure sequence for
which the timing sequence is illustrated in the gure below.
The rst thing to notice is that the FIRE output is high for much of the time. This is because there are no keep cleans
running between each acquisition and hence the exposure time starts on completion of the transfer of the Image area
into the Storage area. This also has the consequence that the exposure time and the cycle time are closely linked. We
have dened the exposure time as the time during which there are no vertical shifts occurring, which also corresponds
to the time during which the FIRE output will be high. The other point to note is that the exposure time overlaps the read
out of the image.
Figure 28: Internal Trigger in Frame Transfer mode