Internal calibration to absolute values in flowthrough particle size analysis.

Using a double-beam technique, a laser flowthrough microphotometer is described that allows internal calibrated size measurements of particles and suspension without the need of reference measurements. Nonspherical particles are oriented in a single file and their longest axes are measured by light absorption analysis. Additional information may be derived from light scattering. The size range is limited only by the flow system, and spans from 2 to 300 microm within a single measurement at the present design. Particle and cell analysis can exceed the rate of 100 000/s. Latex microspheres were analyzed and the data compared to that from microscopic examination. An example of the cell classification obtainable is given for stored human blood.