Roughness measurement of moving weak-scattering surface by dynamic speckle image

In order to meet the needs of in-process measurement in mechanical engineering, we proposed a dynamic speckle method (DSM) for predicting the roughness of moving weak-scattering surfaces. The statistical properties of the dynamic speckle intensity produced by the rough surface were studied. A mathematical model of the recorded dynamic speckle image is built. Then a linear relationship was established between the surface height variance and the natural logarithm of a roughness characteristic parameter extracted from the dynamic speckle image. The theoretical derivations and computer simulations demonstrate that the present method is simple in measuring principle, insensitive to the surface correlation length and resistant to the machine tool vibration, which indicates that the DSM has the potential for in-process application. Finally, an experiment was given.

► We choose the weak-scattering surface as the research object. ► We propose a new dynamic speckle method to measure the surface roughness. ► A roughness characteristic parameter is extracted from a single speckle image. ► The present method features simple measuring system and good vibration-resistance. ► The present method has the potential for in-process or on-line use.