8
operation of the camera as easy as possible. However, developers have full control of these
modes via the DVC camera API.
Refer to
Appendix A
for exposure timing diagrams.
5.2.1.
Continuous, overlapped exposure mode with electronic shuttering
This mode operates the CCD in a “video” mode, in which the previous exposure is being
read out while the current exposure is underway. Once initiated via trigger, the camera
operates continuously in this fashion until halted by the host computer.
Exposure is controlled using “electronic shuttering.” Depending on the user’s exposure
setting, electronic shuttering inhibits the CCD exposure during a specific portion of the
readout interval. Referring to the first figure in appendix A, the shorter the desired
exposure, the longer the inhibition of exposure during the readout of the previous frame.
Regardless of exposure time, frame rate remains constant. The maximum exposure time
in this mode is the time required to read out one frame, and that frame time depends on
the pixel rate, ROI, and binning settings.
Exposure range (full-resolution—no binning or ROI):
20MHz Readout:
Increments of 111.5 microseconds, ranging from 111.5 microseconds
to 235 milliseconds.
40MHz Readout:
Increments of 58.5 microseconds, ranging from 58.5 microseconds to
125 milliseconds.
5.2.2.
Continuous, overlapped, extended-exposure mode
In this mode, exposure and readout are overlapped, but the exposure ranges from one
frame-time (time taken to read out entire frame) to many seconds. This mode is typically
used if intermediate exposure times are desired but with the fastest frame rate possible.
Once initiated via trigger, the camera operates continuously in this fashion until it is
halted by the host computer.
Exposure range (full-resolution—no binning or ROI):
20MHz Readout:
Increments of 111.5 microseconds, ranging from 235 milliseconds to
7480 seconds.
40MHz Readout:
Increments of 58.5 microseconds, ranging from 125 milliseconds to
3925 seconds.
5.2.3.
Continuous, non-overlapped exposure mode
In this mode, the camera alternately exposes and reads out the CCD in a streaming
fashion, without any overlap. This mode allows a wider range of exposures within the
mode, though frame rate decreases with increasing exposure time. Once initiated via
trigger, the CCD operates continuously in this fashion until the camera is stopped.
Exposure range (full-resolution—no binning or ROI):
20MHz Readout:
Increments of 111.5 microseconds, ranging from 111.5 microseconds
to 7480 seconds.
