| 摘要 |
PURPOSE:To reduce the detection limit particle size of fine particles in a liquid, by increasing the intensity of scattering beam due to particles and sensitizing a detector. CONSTITUTION:Detection laser beam 1 and laser beam 2 (destructing laser beam) for destructing or vaporizing the particles 3 in a liquid or forming the same into plasma are allowed to irradiate the liquid. Even when there is no destructing laser 2, a part of the detection laser beam 1 is scattered by the particles 3 but, when the particles 3 are sufficiently small, scattering beam 5 due to the particles is embedded in the Rayleigh scattering beam of the liquid and detection becomes difficult. When the laser beam 2 is allowed to irradiate the particles 3, the particles 3 are changed or formed into plasma corresponding to the power of the laser beam 2 and, according to circumstances, even the liquid around the particles 3 is vaporized or formed into plasma. Therefore, air bubbles 4 are generated at the place where the particles 3 are present and the volume thereof becomes larger than that of the particles. As a result, the fine particles not detected by the beam scattering of the particles 3 themselves are vaporized or formed into plasma to make it possible to detect fine particles.
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