| 摘要 |
PURPOSE:To prevent the influence from being exercised on adhesion of particles to an end surface and to perform a precise measurement, by a method wherein an opposing distance between an end surface of a luminous optical fiber and an end surface of a collecting optical fiber is caused to periodically change at a specified amplitude, and a concentration of particles between the end surface is calculated from a ratio of a maximum to a minimum amount of light collected within a period and an amplitude. CONSTITUTION:Concentration of particle transported in a gaseous manner is measured such that an end surface of an optical fiber 41, emitting light from a light source 43, is positioned facing and opposite to an end surface of a collecting fiber 42, and either of them or a distance between the end surfaces of the two fibers is periodically changed at a specified amplitude x. For example, the fiber 42 is moved forward and backward in a direction of an axis core by means of a device consisting of a gear 45a and a motor 45b. A ratio of a mean value of a minimum value I1 and a maximum value I2 of a light volume collected within a period or a plurality of periods is found from a signal from a light detector 44, and from the value and amplitude x, a concentration m of particles is found by computing it by means of a signal processor 47. This pevents the influence from being exercised on the particles adhered to the opposite ends of the fibers 41 and 42, which results in enabling to perform a precise measurement of the concentration up to a high-concentration range. |
