US 4,251,733 AGranted

Technique for simultaneous particle size and velocity measurement

OwnerEdwin D. Hirleman, Jr.inventor

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Abstract

Two beams of electromagnetic radiation with symmetric radial intensity distributions are directed through space. A particle sampling volume is defined by those portions of the two beams within the field of view of one or more radiation sensitive detectors. The detectors respond to scattered radiation or fluorescence from particles passing through the beams in the sampling volume. The detector output for a single particle indicates two signal pulses corresponding to those times when the particle was in one of the beams. The speed of the particle in the plane perpendicular to the beams is determined from the transit time or width of the signal pulses, and the angle of the particle traverse in that plane determined from the time-of-flight between the signal pulses. The speed and angle thereby determine two velocity components in the perpendicular plane. Then the exact particle trajectory is specified by the angle and one point on the trajectory which is determined from relative magnitudes of the signal pulses. This allows calculation of the radiation intensity incident on the particle throughout the trajectory from known radiation beam properties. A device then responds to the signal pulses to indicate the size or other physical properities of the particle without the ambiguity present if the incident radiation intensity is unknown.

Claims14

Dependent claims

In a system for determining two velocity components and at least one of the physical properties of a particle passing through a particle sampling zone and including:

means for generating two beams of electromagnetic radiation with radially symmetric intensity distributions and for passing said beams of radiation through said zone whereby a portion of said radiation is incident on and is scattered by said particle;
detective means responsive to said scattered radiation for developing a signal indicative of the temporal history of the magnitude or intensity of said radiation incident on said particle during the traverse through said sampling zone where said signal contains two signal pulses separated in time resulting from said particle passing through each of the two said beams in said sampling zone in succession;
means responsive to said signal to determine the speed or velocity magnitude of said particle in the geometric plane normal to said beams from the shape of at least one of the two signal pulses;
means responsive to the time between said two signal pulses in conjunction with said speed measurement to determine the two velocity components in said plane;
means responsive to said two signal pulses in conjunction with said two velocity component measurement to determine an absolute measure of said radiation intensity incident on said particle during passage through said sampling zone;
and means responsive to said signal pulses in conjunction with said measure of said incident radiation intensity to determine a measure of at least one of the physical properties of said particle.

3 more elements

Dependencies are inferred from the claim text.