User`s guide

ACQUISITION MODES
SDK SECTION 4
Page 46
It is also possible to operate a FT CCD in a non-frame transfer mode. In this standard mode of operation, an
FT CCD acts much like a standard CCD. The capture sequence for this standard mode is illustrated here:
• Step 1: Both Image and Storage areas of the CCD are fully cleared out (the Keep Clean Cycle).
• Step 2: When an acquisition begins, the CCD stops the Keep Clean Cycle. The image builds up in
the Image area of the CCD. The CCD remains in this state until the exposure time has elapsed, at
which point the readout process starts.
• Step 3: The charge built up in the Image area is quickly shifted, into the Storage area. The time
required to move the charge into the Storage area is the same as in the Frame Transfer mode.
• Step 4: With the image now in the Storage area the captured image is read out. The time taken to
read out the image is again the same as in the Frame Transfer mode.
• Step 5: On completion of the readout, the CCD is again completely cleared, ready to acquire the next
image. The CCD remains in the Keep Clean Cycle until the end of the accumulation or kinetic cycle
time, depending on the acquisition mode, i.e. back to Step 1. As at least one Keep Clean Cycle is
performed between each exposure, the minimum exposure time is no longer set by the time to read
out the image.
As the captured image is quickly shifted into the Storage area, even in non-Frame Transfer mode, the
system may still be used without a mechanical shutter.