Measurement of surface roughness based on laser angular-speckle correlation method

In order to complete accurate measurement of surface roughness of precision machinery, the experimental light path of surface roughness measurement was designed based on far-field angular-speckle correlation theory. In the measurement light path, a mirror was fixed together with the measured rough surface. While rotating the rough surface, a light pointer was composed by the mirror, beam splitter and receiving screen for measuring the rotation angle, and the measurement accuracy of the rotation angles was improved. During data processing, the peak value calculation method of angular-speckle correlation degree based on MATLAB software was proposed. By means of this method, the measurement procedure was simplified and the measurement speed was improved. And then, the surface roughness was calculated by using the correlation peak value method. As an example, the surface roughness of milling flat was measured. The measurement results were compared with the standard values. High accuracy of measurement was achieved. The results show that the feasibility of measuring the surface roughness by using laser speckle method is verified and the study is helpful to improve the precision measurement of surface roughness further.