Abstract: A particle counter for optically detecting an unconstrained particle of less than one micron in size suspended in a flowing liquid includes a sample chamber having a fluid inlet and a fluid outlet; a laser module producing a laser beam; a beam shaping optical system providing a multiple laser beam pattern in the sample chamber, and a CMOS optical detector located to detect light scattered by the particles in the sample chamber, the detector producing an electric signal characteristic of a parameter of the particle. The particle counter has a particle sensing area within the sample chamber in which the intensity of light is at least 10 Watts/mm2, the sensing area having an area of 0.5 square mm or more. The detector has thirty or more detector array elements. In the preferred embodiment, the laser optical system reflects and refocuses the laser beam to effect multiple passes of the same laser beam through the sensing area.

Abstract: An opaque slurry chemical constituent measurement system includes a cross-flow or membrane filter having a porous filter element connected between a global slurry loop and a spectrometer. The opaque slurry particles cannot pass through the filter element but pass through the filter cartridge into the day tank, while the chemical constituent to be measured permeates through the filter element to the spectrometer, where it is measured, and thence to a reservoir. About once every five minutes the porous filter element is reverse flushed for less than a second to clear the filter pores. One to several times per hour, the reservoir is emptied into the day tank. The system provides essentially continuous measurement of the slurry chemical composition, does not consume reagent chemicals, does not create a chemical waste stream, and provides high reliability and low maintenance by preventing the abrasive slurry particles from contacting the fluidic sampling valves.