A general description of the POLLY system (called "HOLLY" for various obscure reasons) is given, including reasons for some of our choices. The present status of the hardware is that one bay is operating well enough to test the software. Plans for the future are also d i scussed.
DESCRIPTIONIn general, our apparatus is modelled after the "DOLLY" built at Urbana, Illinois. We decided to use four bays each with its own precision CRT, lens, film drive, photomultiplier, etc. The spot is moved on the CRT face exclusively by a digital to analog converter, including the fast sweeps, (There is one DAC for each bay.) All corrections for distortions, pincushion, etc., are done by software from the main computer which, in our case is an EMR 6050 (formerly AS 1 6050), The principle reasons for our choice were that it was certainly necessary to have provision for 4-view film, each film on a separate reel. Although a mechanical scheme for interchanging platens was certainly a possibility, we felt that we could not spare the time (and we were not sure we had the ability) for a good mechanical design that would accurately register each of the platens and without damage to the film. Also, although it will be, at least for the forseeable future, impossible to measure simultaneously on more than one bay, it is possible to go back and forth between bays, keeping the film registered on each bay, and hopefully, if the computer can handle it, use this feature to help match up tracks in different views, even with track shapes like those for the 12 foot chamber. In any case, it is possible to project to move film in other bays while measurements are being made in any desired bay.
