Abstract: Apparatus and method are provided for measuring a dimension of an airborne fiber. The apparatus includes a flow channel for providing a laminar flow to at least a portion of the fibers in air sample and a light source for projecting a light beam along a selected beam path to impinge upon a first fiber in the sample to create scattered light. A portion of the scattered light is measured by a light detector to produce an electrical output which is related to the fiber's dimension.

Abstract: Apparatus and method for measuring the concentration of airborne fibers are provided. The apparatus includes a flow channel for providing laminar flow to a portion of the fibers in an air sample and a light source for generating a light beam directed to the laminarly flowing fibers to produce a scattered light. The apparatus further includes a sensor for sensing a portion of this scattered light and for producing an output from which a fiber concentration estimate can be measured.

Abstract: A method of measuring the size distribution of moving particles within a scattering medium includes a step of directing a beam of light into the scattering medium. The frequency of the scattered light is compared to nonscattered light emitted from the scattering medium and results in the generation of a first signal having a magnitude which is indicative of the difference in frequency between the scattered light and the nonscattered light. A second signal is generated having a magnitude which varies with frequency on a linear scale. The frequency scale of the second signal is then translated to a logarithmic scale. Finally, the translated second signal is deconvolved to determine the size and distribution of moving particles within the scattering medium.