Detection scheme for particle size and concentration measurement

Abstract

The present invention provides a system and method of particle size and concentration measurement that comprises the steps of: providing a focused, synthesized, structured laser beam, causing the beam to interact with the particles, measuring the interaction signal and the number of interactions per unit time of the beam with the particles, and using algorithms to map the interaction signals to the particle size and the number of interactions per unit time to the concentration.

1 . A particle monitoring system comprising a laser that generates a Gaussian beam; means for converting said Gaussian laser beam into a structured dark beam; a focusing lens that focuses said dark beam onto particles moving through the illuminating dark beam; and two detectors wherein one of said two detectors is positioned over each intensity lobe of said dark beam. 
     
     
         2 . The particle monitoring system of  claim 1 , wherein the particles move through the illuminating dark beam in a direction at an angle of 90 degrees relative to the direction of said dark beam. 
     
     
         3 . The particle monitoring system of  claim 1 , wherein the signals from the two detectors are recorded in at least one of the following ways:
 a) as separate signals;   b) as a differential signal of the two detector signals; and   c) as the sum of the two detector signals.   
     
     
         4 . The particle monitoring system of  claim 1 , comprising a beam splitter and a second set of detectors oriented in a perpendicular direction to the dark line of the dark beam. 
     
     
         5 . The particle monitoring system of  claim 1 , comprising a beam splitter and a third detector arranged to allow simultaneous measurement of back scattered radiation from the particles.