Gas or fluid particle analysis using light-scattering - has laser source with opto-acoustic filter and transient recorder for particle identification

摘要

The apparatus for the analysis of particles in fluids or air uses the light-scattering principle. The light source used is a gas-ionisation laser. The secondary radiation emitted by the particles illuminated by the laser beam is passed through an optical system to a continuously-variable acoustic-optical filter. The output of the filter is connected to a photo-multiplier. The electronically scanned output is in a narrow band of wavelengths and each time-point in the scanning cycle corresponds to a definite wavelength of the secondary emission. The photo-multiplier signal at a certain time-point is proportional to the intensity of the secondary emission at that wavelength. A transient recorder stores this information for the electronic processor for identification of the particles.