Adaptive-orientation Measurement And Machining Accuracy Evaluation On Micro-ground Pyramid-structured Si Surface

Compared with etching, micro-grinding has the advantages of high precision and highsurface quality. Microstructure machining accuracy can obtain surface properties of highervalue-added. The contact measurement cannot measure microstructure surface because of thesize and rigidity of contact pin, therefore the use of optical interference measurement isrequired. However, when micro-structured surface morphology is measured by using thewhite light interferometry (WLI), the measured points on steep and smooth micro-structuredprofiles are difficultly captured. Moreover, micro-structured surface evaluation is consideredonly on fine extent and deep to width ratio, so it can not totally reveal characteristics ofmicro-structured surface.Hence, an adaptive-orientation measurement is proposed based on measured point clouddiscrete matching and3D reconstruction. First, micro-pyramid structured surface were groundby micro V-tip diamond grinding wheel on silicon surface. Then, the four micro-groundsurfaces of micro-pyramid-structured surface were measured along the adaptive orientationwith an incidence angle and iterative closest point (ICP) matching was used to reconstruct thewhole micro-ground surface with four adaptive-orientation measured point clouds. Finally,3D reconstruction error and characterized profile error were investigated.Analyzed results shows that average form error after matching was gradually reduced asmatching times increased during measured point cloud matching, and average form error cancome to a convergence value, which is called micro-structured machined form error.Traditional measurement cannot measure the micro-pyramid-structured surface of50μm orless. For the micro-pyramid structured surface with height dimension for142μm, themicro-ground form error of5.5m and the characterized profile error of6.0m may beachieved, respectively.For micro-pyramid structured surface with height of50μm, the feature point error canbe up to15.0μm, which is3times the3D reconstruction error. This is caused by thepassivation of the diamond wheel V-tip. And for that with height of20μm,3D reconstructionwith error of2.6μm can be obtained by adaptive-orientation WLI measurement. Hence, the adaptive-orientation measurement based on the discrete matching and3Dreconstruction can evaluate the micro-structured surface machining accuracy. Moreover,micro-grinding technology can control the hard and brittle materials machining precision.