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Ozu, Akira; Esaka, Fumitaka; Kawakita, Hiroshi*; Okamoto, Ryuta*; Imaki, Masaharu*; Kobayashi, Takao*
Reviewed and Revised Papers Presented at the 23rd International Laser Radar Conference (ILRC-23), p.107 - 108, 2006/07
We have demonstrated that asbestos particles in air can be visualized with laser-induced fluorescence emitted from asbestos. A ultra-violet (266 nm) laser pulse is used to excite asbestos particles suspended in a closed vessel. The fluorescence emitted from the asbestos in the region where the laser beam passes through is detected with a low-pass optical filter and an image intensified CCD camera with ultra-fast gate shutter. Many asbestos particles in the region are separately visualized on an image. It is possible to derive from the image the number and size of asbestos particles through image data processing. The method described in this study is expected to be useful in real-time monitoring of the concentration of asbestos particle.
Ozu, Akira; Okamoto, Ryuta*; Kawakita, Hiroshi*
Kurin Tekunoroji, 16(3), p.56 - 61, 2006/03
In recent years, particle counting devices capable of monitoring particles suspended in air on real-time basis are of considerable practical concern in the fields of semiconductor and large display panel industries. A remote particle counter, which had been developed for monitoring aerosols released in air from nuclear facilities, has been applied to a measurement system for clean rooms used in the fields. It can visualize the particles in narrow space at a distance of 6m and derive the number and size distribution of particles with diameter of above 0.5 microns. By improving the laser energy, sensitivity of the image intensifier camera, and magnification of the zoom lens used in the system, it is possible to detect the particles with diameters of below 0.5 microns. The method and the current performance of the measurement system are described.
Ozu, Akira; Kawakita, Hiroshi*; Okamoto, Ryuta*
Proceedings of 7th International Congress on Optical Particle Characterization (OPC 2004) (CD-ROM), 5 Pages, 2004/00
Optical particle counters (OPCs) using laser light-scattering methods are widely used for aerosol research because they can provide accurate in situ measurements on real time basis. However, in general, it takes a few minutes to count the number of particles suspended in the air. As a novel method, we have developed a remote particle counter (RPC) using an imaging lidar technique, capable of determining with a single laser shot the number and size distribution of particles in the air several meters apart from the observation station. An experimental study has been conducted to calibrate the RPC system. The results obtained in the laboratory test are described compared to those with a conventional OPC using laser light-scattering methods. As the result,the real time measurement of the number and the histogram based on the size distribution of particles in air has been successfully demonstrated with the RPC system.
Sakamoto, Atsushi; Sano, Yuichi; Kofuji, Hirohide; Watanabe, Masayuki; Koizumi, Kenji; Okamoto, Sanae*; Misumi, Ryuta*; Kaminoyama, Meguru*
no journal, ,
no abstracts in English