| 摘要 |
PURPOSE:To accurately perform measurement even when the density of particles is low, in a method for measuring particles to be measured by irradiating the particles to be measured with coherent beam, by forming luminous flux so as to run to the same direction in parallel in a measuring region. CONSTITUTION:Water containing fine particles 20 is made to flow in a flow cell 2 and laser beam is brought to be incident on the side surface 3 of the flow cell 2 from a laser beam source 1. The incident beam is refracted on the wall surface of the flow cell 2 and transmitted through water to be scattered by the fine particles 20 while the greater part of the remainder reaches the side wall 4 to be emitted to the outside while refracted. The beam emitted to the outside is successively reflected by a first reflective mirror 5, a second reflective mirror 6, a third reflective mirror 7 and a fourth reflective mirror 8 and formed into parallel beam which in turn again reaches the side surface 3. The beam transmits through water several times in the same direction. At this time, scattered light by the fine particles 20 is detected by a photomultiplier tube 12. Because the beam is allowed to run in parallel to the same direction to cover a measuring region, low density fine particles can be measured with high accuracy. |
