A Photoelectron Counting System Using a Mini-Computer

A photoelectron counting system has been constructed for the statistical studies of fluctuating light intensities of a limited duration, where a maximal exploitation of the data on time intervals between neighbouring pulses and their sequence in a photoelectron pulse train is required in order to maximize the statistical accuracy of a desired information on the light. The idea that has been adopted here is to collect the data in the computer memory and to use them repeatedly until a complete information is extracted. With this system, approximately 8000 data on pulse intervals ranging from 800 nsec to 2.1 sec can be processed at a time. The performance is demonstrated for He–Ne laser light itself and He–Ne laser light scattered from a suspension of polystylene spheres in water.