A NEW OPTICAL TECHNIQUE FOR ROUGHNESS MEASUREMENT ON MOVING SURFACE

A new optical technique which allows the roughness of moving surfaces to be determined was developed. The new technique which is called the dark/bright ratio (DBR) method utilizes the combined effects of speckl e and scattering phenomena. The roughness of surfaces is inferred from the dimensions of the recorded dark or bright area in the speckle pat tern. Although it is a relative method, it has great potential to be u sed for in-process measurement and automation owing to the simplicity of both its principle and required optical set-up. The new technique h as also been proved to have large measuring range and with high precis ion, The principle of this technique and the set-up of the measuring s ystem are described. Experimental results for both static and dynamic conditions, which were compared to those obtained using the traditiona l stylus technique, were found to be in good agreement. The reliabilit y of the new technique in obtaining roughness data of surfaces under v arious speed conditions (from 0 to 0.017 m/s) was validated. (C) 1998 Elsevier Science Ltd. All rights reserved.