Photozone counters

Optical counters have been widely used to monitor cleanroom technology and particles in oil. Instmments manufactured by Royco Inc. (Menlo Park, California) are available for studying aerosols and particles in Hquids. The HIAC counter (HIAC Instmments, Monte Claire, California) is a widely used stream counter for particles in fluid. One of the more recently developed optical counters is available from Particle Sizing Systems (Santa Barbara, California). The configuration of one of the widely used counters, the Climet counter, is shown in Figure 16. A general review of photozone counters is available (3). 

An example is the Coulter counter. The term sensing zone technique is also used with reference to similar techniques that use light absorption or scattering instead of electrical properties, see Photozone Counter. 

Photozone Counter A particle- or droplet-sizing technique, analogous to the electrical sensing-zone methods, that relies on visible light absorption in sample introduced into a small chamber. The particles or... 

Photozone Stream Counter. Particle size characteristics are deduced from the magnitude and spatial distribution of reflected light signals from the particles to be measured. 

The HIAC Royco Instrument Corporation manufactures a whole range of photozone stream counters [34, 35]. The optical system used in the different instruments depends on the information requirements of the particular study. For example,... 

Figure 6.9. Royco corporation manufactures several different photozone stream counters which exploit different types of light scattering, a) Top view of the optical arrangement of the Model 203 photozone stream counter, b) Optical arrangement Model 218 photozone stream counter. c) Optical arrangement Model 345 photozone stream counter.

Figure 6.10. The Climet photozone stream counter uses an elliptical mirror to collect scattered light and focus it to the photodetector, a) Schematic of the Climet photozone stream counter, b) Typical calibration curve for the Climet counter.

Figure 6.11. The HIAC photozone stream counter characterizes fineparticles by the power drop they cause as they pass through a beam of white l t. a) Arrangement of the inspection zone of the HIAC counter, b) Calibration curve for the HIAC counter showing that the curve deviates from the predicted relationship for power blocked by a geometric shadow.

Figure 6.12. The resolution of the particle size information which can be obtained with photozone stream counters is illustrated by data for a mixture of latex spheres generated by the Particle Sizing Systems Accusizer 770.

The Prototron fineparticle counter is a specialized photozone system used to inspect parenteral solutions for tramp fineparticles [44]. Parenteral solutions are pharmaceutical preparations injected into the body [45]. 

---