Optical Inspection System for the Inner Surface of a Pipe

The inspection for the inner wall is necessary during the life of a pipe from the production to the condemnation. A corresponding optical inspection system has been developed. This system uses the motion of a complicated mechanism in the axial direction droved by a stepper motor, and the detection of panoramic images from the illuminated circumferential inner surface realized by a hemispherical panoramic imaging system (HPIS). Irregularities of images due to corrosion or accumulation of brass deposits on the inner surface are inspected by this system. The experimental system reported in this article has the following specifications: resolution of detection of 0.3 mm at the circumference direction and 1.1 mm at the axial direction of a pipe, and inspection speed of 15 mm/s at an interval of 0.5 mm.