Testing clarity of water by evaluating suspended tiny particles - which diffract laser beam to give flux measured by photoelectric cells

摘要

Full Patentees: Omnium d'Assainissement; Soc. des Applications Biologiques du Laser a l'Environment Sarl, D/S: E(BE, CH, DT, GB, IT, SW). A process of measuring the vol. of particles suspended a liq., the mean dia. (d) of the particles being below a given value, e.g. 10 microns, uses a laser beam which is diffracted by passing through a sample of the liquid. The novelty is that photo-electric cells are used to measure the flux diffracted into at least two apertures. For a helium-neon laser beam, the limiting value (S) of the angle of diffraction of the aperture nearest to the central axis of the incident beam must satisfy the equation S = 0.8 / d, 'S' being in radians and d in microns. The resulting electric signals (F & F') derived from the photo-electric cells are weighted and added together to provide a final signal proportional to the vol. (V) of particles in suspension. The relationship is Vd = aF + a' F' where a and a' are weighting coefficients. The process is partic. applicable to continuous control of effluent clarification by flocculation.