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speed channel is optimized for fast readout with a dedicated, high speed A/D converter and analog
signal path.
Regardless of the readout rate, each channel utilizes its own precision, 12-bit analog-to-digital converter.
The 12-bit digital image data is available to the host computer via the CameraLink interface. The user
can choose the readout channel through software control.
The DVC-4000 has five basic operating modes described in detail below. Each mode can be operated at
either 20 or 40 MHz and can support binning and region of interest. Cooled cameras utilize proprietary
timing to completely remove “diode glow” from the CCD circuitry during long exposures.
All operational modes are initiated by a trigger signal. In the case of continuous modes, the trigger
initiates the stream and the camera continues to run in streaming mode until explicitly disabled. The
edge-triggered, single-frame mode produces one exposure in response to the leading (falling) edge of the
trigger signal. Finally, in bulb mode, the camera exposes for the duration of the trigger pulse, beginning
on the leading (falling) edge and ending on the trailing edge. Readout occurs immediately after the
trailing edge.
The trigger signal can have three different sources: the external, TTL trigger via the auxiliary connector
(see appendix B), the software-controlled trigger via a hard-wired CameraLink camera control line, or
the software-controlled through camera trigger command, via the CameraLink 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
The DVC-4000 is capable of operating at pixel rates of 20MHz and 40MHz via independent
channels optimized for the given speed. 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 coolest 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-4000 is capable of
approximately 38,000 electrons dynamic range, twice that of many other scientific
cameras.
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 heat generation and significantly lower dynamic
range. Because of amplifier limitations on the KAI-4021 CCD, the DVC-4000 is capable
of approximately 20,000 electrons dynamic range at 40 MHz.
5.2.
Operational modes
The following section describes the distinct operating modes of the DVC-4000 cameras. Users
of DVCView software will find many of these modes seamlessly integrated together to make
