Optics: measuring and testing – For size of particles – By particle light scattering
Patent
1997-11-25
1999-02-09
Pham, Hoa Q.
Optics: measuring and testing
For size of particles
By particle light scattering
356339, G01N 1502
Patent
active
058701907
ABSTRACT:
A method for counting, by ranges of size, particles flowing through a particle sensor including the steps of flowing a particle through the sensor, thereby producing a voltage pulse which is sampled over a period of time. Sampling yields a plurality of voltage values which includes a latest value and a former value. The latest value is compared with the former value and when less than the former value, the method finds, in a table of threshold voltages, the size range for the particle. A counting bin corresponding to the size range for the particle is then incremented. The former value may be the value immediately preceding the latest value or it may be several "counts" prior to such latest value. The new particle sensor has an inlet, sensing volume, exhaust port, light collection system and an electronic system coupled to the light collection system. The electronic system is programmed to count particles, by size, in any of several unique ways. Depending upon the embodiment, the method and sensor offer improved discrimination to help avoid counting floaters, false peaks and the like.
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Pham Hoa Q.
Venturedyne Ltd.
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