| 摘要 |
PROBLEM TO BE SOLVED: To solve problems that dust collection by filtration and enlarged observation are required to be executed separately, and that it is difficult in a work to obtain the size distribution of particles. SOLUTION: Illumination light reflected totally by an observation surface 11a of a prism 11 is irradiated by light generators 13a, 13b from an incident surface 11b of the roughly trapezoid-shaped prism 11. Hereby a near field is formed on the observation surface 11a, and when particles arrive, they are illuminated by near-field scattered light. When the change of quantity of light is detected by optical sensors 16a, 16b through an optical system 15 facing to the observation surface 11a, the population of the particles can be counted based on the change of the quantity of light, and a frequency distribution can also be obtained because an output ratio between both sensors 16a, 16b is equivalent to the magnitude of the particles.
|
