To improve continuous and automatic measurement precision of blown snow or blown sand by using a light emitting element which is a sufficiently practical spot light source as compared with the size of particles to be measured and has high light output.
At a light-projection part 1, a superluminescent diode which has wide light emission spectrum width, low coherence characteristics, and high light output is used as the light emitting element, and stored in a case 5 which has drip-preventive glass 4 together with a collimator lens 6, and parallel light beams are projected. At a photodetection part 2, a PIN photodiode with a condenser lens is used as a light receiving element and put in a case 9 with drip-preventive glass 8 together with a slit plate 10, and all of light passed through a measurement area R is detected through a slit 10a, outputted to a preamplifer part, and inputted to a signal processing part after specific processing. Then the output signal of the preamplifier part is amplified, and the size of particles, counts by particle size, flow rates by particle size, etc., are continuously and automatically measured and recorded through 3/2-th power operation for converting the wave height value of pulses to the diameter and volume of the particles, peak holding, and integrating operation.
ISHIMARU TAMINOE
KATO TSUTOMU
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