Specifications

Chapter 5 Timing Modes 49
Free Run
In the Free Run Kinetics mode, the controller takes a series of images, each with the Exposure
time set through the software (in WinView32, the exposure time is set on the Experiment
Setup|Main tab page). The time between image frames, which may be as short as a few
microseconds, is limited by the time required to shift an image under the mask: this interimage
time equals the Vertical Shift rate (specified in
µsec/row) multiplied by the Window Size (the
number of rows allocated for an image frame). The exact number of frames depends on the
selected Window Size and is equal to the number of pixels perpendicular to the shift register
divided by the Window Size.
Example: Referring to the readout shown in Figure 20, there are 6 pixels perpendicular
to the shift register and the Window Size is 2 pixels high. The number of frames is 3. If
the Vertical Shift Rate for the CCD is 1.6
µsec/row, the Shift time will be 3.2 µsec per
frame.
Integrate signals (Shutter Monitor) or Readout signals (NOT SCAN) are provided at the
BNC for timing measurements.
SCAN Signal
Shutter
open time
Shutter
close time
Readout
Exposure
Shift
Shutter Monitor Signal
STARTACQ
Sent when ACQUIRE or
FOCUS is clicked on in the software.
Figure 23. Free Run Timing Diagram
Single Trigger
Single Trigger Kinetics mode takes an entire series of images with each External Trigger
Pulse (applied at the Ext. Sync BNC on the control board of ST-133/ST-133A). After the
series is complete the shutter closes and the CCD is read out at normal speeds. Once the
readout is complete the detector is ready for the next series of exposures. This timing is shown
in Figure 24, where a single External trigger pulse is used to collect a burst of 6 frames.
Readout
External Trigger
Exposure
Shift
Shutter Monitor Signal
Sent when ACQUIRE or
FOCUS is clicked on in the software.
STARTACQ
SCAN Signal
Shutter
open time
Shutter
close time
Figure 24. Single Trigger Timing Diagram