CLOSED LOOP SCANNERS (such as CTI6800 / CT6210)

If you have a set of closed loop scanners, it is important to tune them to one of the ILDA standard tuning patterns. The idea of tuning to a standard test pattern is that artwork produced on one system can be exchanged and displayed accurately on another system that has also been tuned to a standard pattern. This is important if you wish to use artwork created by other people, or indeed trade your own artwork with others. It also means that if you have more than one projector, if they are all tuned to the same standard, then the images should look pretty much the same.

The speed which you decide to choose to tune your scanners to is largely dependent upon which type of scanners you have. GSI - G120 Scanners are normally only able to be tuned the 12K standard (unless you have special Turbo amplifiers). High speed scanners, such as the Cambridge CT6210, are best set to the 30K standard.

One important point to remember is that whilst a set of scanners may be tuned to either 12K or 30K. The normal artwork you produce can be created at any scan speed, you do NOT have to product artwork at 12K just because your scanners are set to the 12K tuning pattern. Normally, it is general practice to use a speed which is about two thirds of the 'tuned' speed for producing artwork, i.e. 8K pps for a 12K system and 24K pps for a 30K system.

OPEN LOOP SCANNERS

Open loop scanners, are more suited to creating basic aerial and beam effects, ie. single tunnels. The graphics produced by open loop scanners tends to be limited to very simple images. In fact a number of people have described the images as looking like a young child's drawing efforts; as shown in the examples below. Having said that, there is nothing wrong with open loop scanners if your shows are based upon simple aerial effects and you have a large enough optics table within your laser system to house this type of scanner.

Closed loop scanners output @ 30K pps	Open loop scanners output