Laser heterodyne apparatus for measuring small angle scattering from particles

A laser heterodyne apparatus for measuring small angle scattering from streaming particles in gases and liquids has been developed. A diffraction grating is used to create the local oscillator light beam, which makes the apparatus simple and practical to handle. A quantitative theory of the complete apparatus is presented together with experimental confirmation by measurements on water suspensions of latex spheres with known diameters and concentrations. The apparatus could be used to measure continuously mass contents and mass flows in streaming media.