Research On Three-dimensional Measurement Method Of Binocular Structured Light Microscopy Based On Scheimpflug Telecentric Optical Pat

In recent years,with the widespread application of microelectromechanical systems(MEMS)and the miniaturization and precision of industrial manufacturing,microscopic 3D contour measurement methods have gained widespread attention.With its advantages of high precision,high efficiency,non-contact and low cost,structured light projection technology has a broad application prospect in the field of industrial microscopic 3D inspection.However,there is still a lack of research on high precision and large depth of field structured light microscopic 3D measurement methods.Therefore,we study the binocular structured light microscopic 3D measurement method based on Scheimpflug telecentric optical path to provide high-precision and large depth of field 3D contour data for precision industrial inspection.The main research work and innovation points are summarized as the following aspects:(1)To resolve the problem of limited depth of field in traditional multi-view threedimensional microscopic measurement,we innovatively combined the Scheimpflug principle with the binocular telecentric microscopy system.The method greatly improves the spatial coincidence rate of the object field of view between the multiple viewing angles of the telecentric microscope optical path,and realizes the expansion of the measurement depth of field.(2)Due to the introduction of additional tilt between the camera sensor and the optical axis under Scheimpflug conditions,the traditional camera calibration method is no longer applicable.In response to the problem,we derives a new model of the telecentric optical path under Scheimpflug conditions,and studies a camera calibration method that does not need to solve the tilt angle.(3)In order to reduce the complexity of the algorithm in the binocular matching process and improve the accuracy of 3D reconstruction,based on the plane calibration model,we studied a binocular telecentric stereo correction method under Scheimpflug conditions,which can effectively reduce the calculation based on 3D reconstruction and improve the accuracy of3 D reconstruction.(4)We designed and constructed a set of binocular structured light microscopy 3D measurement system based on Scheimpflug telecentric light path.By selecting appropriate hardware units,building a software architecture with separate front and back ends,and rationally using multi-threading and GPU acceleration to improve software operating efficiency,a complete microscopic 3D scanning function from calibration to 3D display is realized.In the experiment,3D measurement of micro devices such as ceramic plates,industrial ceramic parts,and chips packaged as BGA was carried out.Experimental results show that the measurement accuracy of this system can reach 1.192 μm,and the measurable depth of field can reach 8 mm.