ALLIED Vision Technologies Bonito CL-400 200 fps - Manual (Page 54)

Parameters and commands
Bonito Technical Manual V2.3.0
54
Internal charge
transfer and readout The internal charge transfer of the first image is started with some fixed delay
and it takes the time of one line duration (t
L
). The end of the charge transfer
effectively terminates the exposure of the first PIV frame and internally starts
exposure of the second PIV frame.
During any charge transfer, the sensor‘s photo detectors keep integrating
charge. Even the charge that is newly integrated during the transfer process, is
transferred to the sensor‘s pixel memory. I.e. a strobe or flash pulse that is fired
during the charge transfer will contribute to the image.
Once the charge transfer for the first frame is completed, the new charge that
integrates within the sensor‘s photo detectors, will contribute to the next
frame.
The internal readout of the first PIV frame, from the sensor‘s pixel memory to
the Camera Link output ports, starts directly after the end of charge transfer. It
takes the time of (N+1) line durations.
At the same time, the sensor‘s photo detectors continue to integrate charge,
even during the readout process. The charge accumulated during this phase
contributes to the exposure of the second PIV frame.
The internal charge transfer of the second PIV frame automatically starts
directly after the internal readout of the first PIV frame is complete. It takes the
time of one line duration (t
L
), during which the sensor‘s photo detectors keep
integrating charge for the second PIV frame.
When the charge transfer of the second PIV frame is complete, its internal read-
out starts automatically, which also takes the time of (N+1) line durations.
During this phase, the exposure of the next first PIV image has already started.
However, this image already belongs to the succeeding PIV image pair, which is
not yet triggered at this stage.
After readout of the second PIV frame from the pixel memory is completed, the
trigger may start the whole sequence anew. However, the camera needs at least
one line duration of dead time before it is ready for the next trigger event, pro-
vided the camera is not configured to continuous mode (e.g.
M=4).
Synchronization
output The synchronization output signal determines how the images are paired by
externally communicating the start and end of each PIV sequences‘ first charge
transfer. It allows to synchronize external devices, such as flashes, with the PIV
sequence.
The falling edge at synchronization output signals that the charge transfer of
the first PIV frame has begun (See
Figure 28: PIV mode flow diagram on page
56). This requires the setting J=1, it may be used to trigger the first flash pulse,
but the recommended guard interval t
G1
of the flash pulse should not be under-
cut.