optical ring (OptoRing).



Since 1988 a fairly large number of camera systems has been build at the Niels Bohr Institute ( NBI ). The systems has ranged from small systems with a single CCD-device, to infrared systems and mosaics with state of the art detectors. A lot of experience is gained during the years, and a lot of it have already resulted in changes and upgrades of the existing design, resulting in a much higher stability and precision of  the latest cameras. In the construction of the third generation of CCD-controllers, special efforts has been taken to improve the speed performance and system flexibility without compromising power consumption, stability and low noise performance of the previous generation.


System overview

The NBI generation 3 camera system (CCD3) (Fig.1) consists of two major components, - the CCD3-controller that is clamped onto the unit containing the detector ( usually a kind of dewar), and a PCI-card, - normally hosted inside a PC. One or more of each of these units are interconnected by an optical fibre, - either point to point or in a ring-shaped configuration, allowing more units to be inserted within the same optical ring (OptoRing).


Each controller is a small self contained unit that cannot be expanded. The internal power supply supports up to 16 video channels and 96 clock drivers. If larger systems are needed, the controller is equipped with a syncronisation mechanism, allowing a cluster of controllers to work together as one unit.

Control of operation ( SW )

The OptoRing supports simultaneously transfer of bulk data (pixel data) and single characters with full handshake (commands). This command channel enables continuous exchange of commands and status between acquisition software in the host computer and software running local in the controller by means of an assisting uP on the sequencer-board. To facilitate this operation a set of commands and status-requests is defined, - the CCD3-command-set.