Specifications

Version 1.1 rev Jan 2013
Page 57
iXon Ultra
, Features and Functionality
3.4 - ACQUISITION OPTIONS
3.4.1 - Capture Sequence in Frame Transfer (FT) Mode
A number of acquisition modes are available for the iXon Ultra range to best suit your experimental demands. In Frame
Transfer (FT) acquisition mode, the iXon Ultra can deliver its fastest performance whilst maintaining optimal Signal to
Noise. It achieves this through simultaneously acquiring an image onto the image area whilst reading out the previous
image from the masked frame storage area. Thus there is no time wasted during the readout and the camera operates
with what is known as a 100% ‘duty cycle’.
Figure 18: Capture sequence (FT mode)
Step 1 Both Image and Storage areasoftheEMCCDarefullycleanedout.Thisisknownasa"KeepClean
Cycle"(KCC).KeepCleanCyclesoccurcontinuouslytoensurethatthecameraisalwaysreadytostartan
acquisition when required. Further details of the Keep Clean Cycle are given later.
Step 2 On receipt of a Start acquisition command the EMCCD stops the Keep Clean Cycle. This allows the image
(photoelectric charge) to build up in the Image area of the EMCCD. The EMCCD remains in this state until
the exposure time has elapsed, at which point the readout process starts.
Step 3 The rst phase of the readout process is to quickly shift the charge, built up in the Image area, into the
Storage area. The time required to move the charge into the Storage area is approximately calculated as
follows: (No. of rows in the Image area) x (vertical shift rate).
Step 4
Once the Image area has been shifted into the Storage area the Image area stops vertically shifting and
begins to accumulate charge again, i.e. the next exposure starts. While the Image area is accumulating
charge the Storage area is being read out. This readout phase can take tens of milliseconds to seconds
depending on the image size, readout pattern and readout speed.
Step 5
On completion of the readout, the system will wait until the exposure time has elapsed before starting the
next readout (i.e. returning to Step 3).