| 摘要 |
PROBLEM TO BE SOLVED: To provide a suspended dust measuring apparatus capable of accurately measuring the particle size distribution of suspended dust slightly contained in air up to a measuring lower limit of about 0.1μm. SOLUTION: Sample air As containing suspended dust and clean air Ac are alternately supplied to the laser beam irradiation region of a measuring part 2 by an air supply/changeover means 3 and the detection signals of diffracted/scattered beams are converted to AC currents by optical sensors 41 ... The outputs of the optical sensors 41 .. are subjected to AC amplification by a signal processing circuit 5 to be detected and the detected results are digitalized to be supplied to an operation means 6 based on the theory of a laser diffraction/scattering type particle size distribution measuring apparatus to make it possible to measure even the accurate particle size distribution of a low conc. sample.
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