| 摘要 |
PURPOSE:To measure the radius of a particle and the numerical density of impurity particles in a fluid directly, by performing computation, based on the phase difference between a photo- acoustic signal from a measuring cell, which is filled with a fluid sample, and a reference signal, and a photo-acoustic signal, which is induced by scattered light due to the impurity particles in the fluid sample. CONSTITUTION:Incident light with intensity I, which is modulated by an acoustooptic means, is inputted to a measuring cell, which is filled with a fluid including impurities, whose particle radius is (d) and numerical density is N. A phase difference phi' between a photo-acoustic signal when output light has a peak value and the photo-acoustic signal of the input light, which is to become a reference signal, is detected. The radius (d) is excellently computed based on an expression I in correspondence with one-dimensional value even though the radius is small. Meanwhile, thermal elastic waves are generated in a detector by the scattered light due to particles in the detector of the measuring cell. The photo-acoustic signal Sd, which is induced by the thermal elastic waves, is detected. The numerical density N of the impurities is determined by an expression II. In this way, the particle radius and the numerical density of the impurity particles in the fluid can be directly measured. In the expressions, k1 and k2 are constants, (f) is a light modulating frequency, R is a distance between a light axis and the detector, and (v) is light speed in fluid. |
