METHOD AND APPARATUS FOR MEASUREMENT OF INSIDE ROUGHNESS OF SLENDER PIPE

摘要

PURPOSE:To measure roughness inside a long slender pipe in a nondestructive manner. CONSTITUTION:A laser beam which is reflected inside a slender pipe 2 in a multiple manner and which is radiated is condensed on a photodetector 40 by a condensing lens 30. The quantity of light of the specular reflection component and the quantity of the scattering reflection component of the laser beam which is radiated from the center-part light-receiving part 41 and the peripheral-part light-receiving part 42 of the photodetector 40 are detected separately. Photocurrents from the central-part light-receiving part 41 and the peripheral-part light-receiving part 42 are input to a signal processing circuit 50. The ratio of the quantity of received light of the central- part light-receiving part 41 to the quantity of received light of the peripheral-part light-receiving part 42 is operated in the signal processing circuit 50. The inside roughness of the slender pipe 2 is evaluated on the basis of the ratio. By this constitution, the inside roughness of the slender pipe 2 can be inspected with high accuracy and in a nondestructive manner without being affected by a change in the quantity of light incident on the slender pipe 2 and by the shift of the optical axis of the incident light.