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Measurement of velocities and diameters of small particles by using fast digital circuits for the on‐line evaluation of laser‐doppler‐signals
Author(s) -
Bauckhage Klaus,
Schöne Armin
Publication year - 1985
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.19850020120
Subject(s) - photodetector , electronic circuit , signal (programming language) , computer science , interface (matter) , line (geometry) , digital signal processing , digital electronics , laser , digital signal , personal computer , doppler effect , signal processing , electronic engineering , computer hardware , optics , electrical engineering , physics , engineering , mathematics , geometry , bubble , astronomy , maximum bubble pressure method , parallel computing , programming language
Inspection of the scattered light by two photodetectors makes it possible to investigate the velocities of droplets as well as their size in disperse systems and has some advantages against related methods. When this method is used, the size of the droplets can be derived from the phase difference of the signals from the first and the second photodetector. Special problems of this method are discussed in the paper. A system with fast signal processing facilities, working mostly digitally, was developed in order to solve these problems. This system derives several digital signals from the signals of high frequencies that are gained from the photodetectors. These digital signals are combined by digital circuits of the ECL‐type. The resulting pulse series are fed into several digital counters. The data from the counters and from some other inputs are further processed by a real time computer that was developed for this special task, using an 8088 micro processor. This real time computer is connected to an ordinary personal computer by a parallel interface.