Measurement of three‐dimensional shape and section of object on turntable by position‐sensitive device

Abstract

This paper considers an object moving on a belt‐conveyor or on a turntable, and describes a system which measures with a high speed its shape and the cross section in horizontal and vertical directions. In the measurement, the object is scanned with a high speed by He‐Ne spotlight through a high‐speed rotating mirror with 10 mirror‐faces. The object is placed on a turntable and rotated 360 deg by a stepping motor. The two‐dimensional information of the scanned point is acquired by PSD. The operation is performed in synchronization to the scanning by a personal computer, and the cylindrical coordinates (r, z, θ) of 4800 points on the object are determined with as high a speed as 980 ms (200 μs per coordinate). A feature of this study is that the speed is improved by combining a high‐speed rotating mirror and a high‐speed PSD. Another feature is that the reference table for coordinate determination is stored so that the speed of the computation can be improved. At present, approximately 3 min is required by BASIC to display the coordinates, but the cross section can be displayed in 0.4 s using the machine language.