Particle detection beam

Apparatus for use in identifying particles that are present in fluid, which includes a beam generator that generates a beam of light that is generated along a beam path, wherein:

• said beam of light has a beam width and a beam thickness, in directions that are perpendicular to each other and that are each perpendicular to said beam path, said beam width being a plurality at times as great as said beam thickness;
• and including:
• a quadrant detector that includes four photodetectors lying in each of the four quadrants formed by two perpendicular line areas, said quadrant detector lying along said beam path to be illuminated by said beam during a test;
• a difference circuit that generates a signal representing the difference in outputs of opposite ones of said photodetectors;
• said quadrant detector being oriented with each of said perpendicular lines extending about 45° to the directions of said beam width and to same beam thickness.

Apparatus for use in identifying particles that are present in fluid, which includes a beam generator that generates a beam of light that is directed along a beam path, wherein:

• said beam of light has a beam width and a beam thickness, in directions that are perpendicular to each other and that are each perpendicular to said beam path, said beam width being greater than said beam thickness;
• a quadrant detector that includes four photodetectors lying in each of the four quadrants-formed by two perpendicular line areas, said quadrant detector lying along said beam path to be illuminated by said beam during a test;
• a difference circuit that generates a signal representing the difference in outputs of opposite ones of said photodetectors;
• activator means for moving said quadrant detector relative to said beam, in a direction primarily parallel to said beam width, to thereby enable a determination of a cross-sectional dimension of said beam.

Apparatus for use in identifying particles that are present in fluid, which includes a laser that generates a beam of light that is directed along a beam path, wherein:

• said beam of light has a beam width and beam thickness, in directions that are perpendicular to each other and that are each perpendicular to said beam path;
• a photocell positioned along said beam of light;
• a circuit connected to said photocell that indicates the output of said photocell;
• a polarizing filter positioned along said beam of light;
• means for rotating said photocell relative to said laser.

Apparatus for use in identifying particles that are present in fluid to be analyzed, wherein the fluid moves largely along a predetermined fluid movement direction, which includes a beam generator that generates a beam of light, and a plurality of detectors that each detects light scattered from a detection zone lying along the beam when a particle passes through the detection zone, wherein:

• said beam generator is constructed to generate a light beam moving along a predetermined beam direction and having a beam width and a beam thickness as measured in directions that re perpendicular to each other and that are each perpendicular to said fluid movement direction, whereby to minimize the time for passage of each particle through said beam and maximize the number of particles passing through said beam per time period;
• a dump positioned along the path of said light beam, said dump having at least one photocell for detecting light;
• a circuit for measuring the output of said at least one photocell;
• a polarizing filter lying along the path of said light beam between said beam generator and said photocell;
• said beam having an axis extending along said beam path, and of said beam generator and said filter, means for rotating one of them relative to the other about said axis.

Apparatus for use in identifying particles that are present in fluid to be analyzed, wherein the fluid moves largely along a predetermined fluid movement direction, which includes a beam generator that generates a beam of light, and a plurality of detectors that each detects light scattered from a detection zone lying along the beam when a particle passes through the detection zone, wherein:

• said beam generator is constructed to generate a light beam moving along a predetermined beam direction and having a beam width and a beam thickness as measured in directions that are perpendicular to each other and that are each perpendicular to said beam direction;
• said beam width is a plurality of times as great as said beam thickness, and said beam thickness extends primarily parallel to said fluid movement direction, whereby to minimize the time for passage of each particle through said beam and maximize the number of particles passing though per beam per time period;
• a quadrant detector that includes four photocells each lying in one of the four quadrants formed by two perpendicular line areas where light is not detected by one of the four photocells, said quadrant detector lying along said beam path to be illuminated by said beam during a test;
• a difference circuit that generates a signal representing the difference in outputs of opposite ones of said photocells;
• said quadrant detector being oriented so said perpendicular line areas are each inclined by about 45° from the horizontal when said beam width is horizontal.

A method for identifying particles that are present in fluid to be analyzed wherein the fluid moves largely along a predetermined fluid movement direction, which includes generating a beam of light that moves along a light path and detecting light scattered from a particle passing through a detection zone that lies along said light path of the beam, wherein:

• said step of generating a beam of light includes producing a beam that has a cross-section at said detection zone wherein said cross-section has a width in width direction that is perpendicular to said light and that is primarily perpendicular to said predetermined fluid movement direction, and wherein said cross-section has a thickness in a direction perpendicular to said width and to said light path;
• said step of producing a beam includes producing a beam whose width is more than five times its thickness at said detect zone;
• placing a quadrant detector that has four photocells lying in different ones of four quadrants separated by two perpendicular line areas, along said light path in a test;
• detecting differences in the outputs of a pair of diagonally-opposite ones of said photocells to determine the accuracy of centering of said beam on said quadrant detector;
• said step of placing including orienting said lines areas so they each extend about 45° to the horizontal when said width direction of said beam is horizontal.