Nonmechanical and multiview 3D measurement microscope for workpiece with large slope and complex geometry

Due to the large slope and complex geometry, it is difficult to measure the three-dimensional parameters of cutting tools and drill bits by using general optical measurement method. A method that combines the multiview rotation scanning and nonmechanical focus variation by using a liquid lens is proposed in this paper. Firstly, the workpiece is rotated by using a rotation unit, and in every rotation position, a sequence of images of the workpiece are captured in the axial direction. Secondly, the relative degree of focus is measured for all pixels by using focus measure operators to obtain the depth value corresponding to each pixel. Thirdly, a multiview registration algorithm is designed to combine all the individual data sets at each rotation position into a whole three-dimensional point cloud. Finally, the three-dimensional parameters of the rake angle and clearance angle of the gear, screw tap and drills are measured. The proposed method is lateral shift-free and no light intensity variation, so it can obtain better accuracy. The experimental results show that the accuracy of the axial measurement reaches 2.4 μm (2σ, Nikon 5×/0.1).

This article is about a method that combines the multi-view rotation scanning and non-mechanical focus variation by using a liquid lens.