7
the software-controlled through camera trigger command, via the Camera Link serial port. Developers
should consult the DVC Camera API documentation for further information on the software-controlled
triggers.
If the TTL, external trigger is used, the trigger signal must be active-low. The trigger point is the high-to-
low (leading edge) of the trigger signal.
5.1.
Operating speed and single/dual port option
The DVC-4000D is capable of operating at pixel rates of 20MHz and 40MHz and with single or
dual-port options as described above. All camera functions (e.g. exposure mode, binning, ROI,
etc.) are operational at either speed, subject to the limitations below.
5.1.1.
20 MHz operation
20MHz operation gives the user the maximum dynamic range, minimum noise floor,
and lowest-power operation. Dynamic range refers to the maximum signal swing under
which the camera meets performance specifications, and it is expressed in the maximum
number of captured electrons on the CCD. At 20MHz, the DVC-4000D is capable of
approximately 35,000 electrons dynamic range.
5.1.2.
40 MHz operation
40MHz operating speed provides the user with the highest capture frame rates at the
expense of slightly higher noise and power dissipation. Because of amplifier limitations
on the KAI-04022 CCD, the DVC-4000D is capable of approximately 20,000 electrons
dynamic range at 40 MHz.
5.1.3.
Single-port and dual-port options
The DVC-4000D is capable of readout via a single port (all four million pixels read out
through a single 12-bit channel) or dual-port in which the image is split down the middle
in the “slow scan” direction and each half is read out simultaneously, using two 12-bit
channels. The port options are available in both 20 MHz and 40 MHz, and for all
operational modes. Dual-port operation can result in slight signal mismatch between the
two image halves, due to differences in the signal path components. This can be easily
compensated in most applications.
5.2.
Operational modes
The following section describes the distinct operating modes of the DVC-4000D cameras. Users
of DVCView software will find many of these modes seamlessly integrated together to make
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 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