Abstract: A back scattering collector, comprising: a first spherical reflective surface; a second spherical reflective surface having an annular form defining a central aperture; a refractive element, the first and second reflective surfaces and the refractive element being aligned along an optical axis; a light excitation source for illuminating a volume for analysis; the first and second reflective surfaces having respective diameters which reflect light rays back scattered from the volume at least three times between the first and second reflective surfaces, a last one of the at least three refections directing the light rays through the refractive element; and, a photo detector, the refractive element focusing the light reflected light rays onto the photo detector. The second reflective surface can be formed on the convex side of a plano-convex lens, the refractive element being formed by a central portion of the lens. The distance between the reflective surfaces is adjustable.

Abstract: An apparatus and method for detecting particles in a clean environment provides for forming a beam of electromagnetic radiation into an instantaneous scattering volume and scanning the scattering volume in space defined by a flow cell. Particles are transported by fluid means into the space occupied by the scattering volume and individual particles are multiply scanned while passing through the scanning scattering volume. A fluid conduit is provided to transport the fluid and the particles and windows are provided to transmit the radiation beam into the space defined by the flow cell and to transmit scattered radiation from the particles out of the space. The radiation from the particles is collected and detected to provide an output signal. In the preferred embodiment, the output signal is analyzed to determine the concentration of the particles in the fluid and to determine the size and velocity of each individual particle.

Abstract: A method and apparatus is disclosed for measuring the mass concentration of particulates entrained in a process or work area. One or more sensors are employed which electro-optically and continuously weigh the effluent extracted from the process area. The effluent is caused to enter a sample volume area either by convection or through a preseparator. The sampling volume is exposed to near infrared radiation of a light emitting diode (LED). An information signal indicative of small and large particulates entrained in the effluent is developed. The signal is converted and classified to signals corresponding to the presence of small or large particulates and further sub-classified as to size. The electro-optical "weighing" signals are operated on to produce a mass concentration read-out via an empirical algorithm exercised by a microprocessor in a centrally-located control/read-out unit which serves a multiple of remote sensors.

Abstract: A calibration/zero control is combined with an electro-optical measurement instrument in a time-multiplex fashion to provide a self-diagnostic in situ measurement system and automatic compensation of the entire electro-optical train without interruption of the measurement process. The electro-optical instrument includes a laser which provides a source of substantially monochromatic electromagnetic radiation (laser beam) and optics for collection and focusing radiation onto a detector. The radiation is directed through a sampling volume where it impinges upon an object whose properties or physical characteristics are to be measured by scattering techniques. The calibration/zero control includes an element rotatably positioned in the path of the electromagnetic radiation, optically upstream of the sampling volume, in having an axis of rotation perpendicular to the optical axis such that the radiation is periodically blocked and sampled.

Abstract: A calibration/zero control is combined with an electro-optical measurement instrument in a time-multiplex fashion to provide a self-diagnostic in situ measurement system and automatic compensation of the entire electro-optical train without interruption of the measurement process. The electro-optical instrument includes a laser which provides a source of substantially monochromatic electromagnetic radiation (laser beam) and optics for collection and focusing radiation onto a detector. The radiation is directed through a sampling volume where it impinges upon an object whose properties or physical characteristics are to be measured by scattering techniques. The calibration/zero control includes an element rotatably positioned in the path of the electromagnetic radiation, optically upstream of the sampling volume, in having an axis of rotation perpendicular to the optical axis such that the radiation is periodically blocked and sampled.