Research On Micro Probe Technologies Based On Orthogonal Micro Focal-length Collimation

With the rapid development of micromanufacturing,the microstructure parts with characteristic dimensions ranging from a few micrometers to approximately 1 mm or large parts with microstructure arrays are widely used in the field of high-end equipment manufacturing.Simultaneously,the manufacturing precision of these microstructures is critical to the performance of the core devices.For example,the size and topography error of the array cooling micro holes on the aero engine can seriously impair the cooling efficiency of its gas film.The geometry error of the diesel engine injector nozzles will greatly reduce the atomization behavior,which results in reduction of combustion efficiency and increase of pollutant emissions.The performance of microstructure devices such as microgears,microlens and microlens arrays,microfluidic channels,and medical microneedle arrays is also highly dependent on the microstructure manufacturing precision.High-precision measurement technology is the key to control the manufacturing precision of the microstructures,and is also the guarantee for the excellent performance of the microstructure devises.However,the measurement accuracy of current micro probe technology is low,and becomes the main source of uncertainty components of microstructures measurement.The existing micro probe technology is not capable of the high-precision measurement tasks for microstructures,which restricts the improvement of microstructure manufacturing precision.Focusing on the three-dimensional(3D)high-precision measurement requirements of microstructures,research works on micro probe based on principle of orthogonal micro-focal collimation are carried out by theoretical modeling,simulation analysis and experimental verification,to solve the problem that the existing fiber probes cannot achieve 3D high-precision micro displacement measurement,and the problem of measurement accuracy reduction of the existing elastic probes due to the inability to measure the stylus deformation and measurement characteristic anisotropy.New principle and methods will be provided for microstructure measurement.The main research works and results are as follows:Firstly,research on the fiber probe based on orthogonal fiber collimation is carried out.The principle of fiber collimation is analyzed,the deformation models of the fiber stylus are built,and then the transfer functions of the fiber probe are obtained.The displacement transfer ratios and forces of the fiber probe are also analyzed.When the fiber stylus is subjected to touch force,the fiber stylus deflects or buckles.The deflection and buckling deformations of the fiber stem at the observation point will be detected via the orthogonal fiber collimation optical paths.Thus,the 3D micro displacements of the fiber stylus are transformed into centroid position shifts of the fringe images.The analysis results show that the fiber probe can realize 3D micro displacement measurement with high-precision.Secondly,research on the elastic probe based on orthogonal micro-ball collimation is carried out.The principle of micro-ball collimation is analyzed,the deformation model of the elastic probe is built,and then the transfer function of the elastic probe is obtained.Utilizing the rotation and translation of the elastic suspension,the 3D micro displacements of the probe tip are transferred to that of the micro-ball of the transfer stylus which is arranged in reverse coaxial direction to the measuring stylus,and the displacements of the micro-ball will be transformed into centroid position shifts of the collimating light spots by the orthogonal micro-ball collimation optical paths,high-precision decoupling measurement of 3D micro displacements of the probe tip can be realized.The experimental results show that the orthogonal micro-ball collimation optical paths can realize the decoupling measurement of 3D micro displacements,its 3D measurement ranges are-10 ?m ~ 10 ?m,-10 ?m ~ 10 ?m,and 0 ?m ~ 10 ?m,respectively,and the resolution is 3 nm.Thirdly,research on three-dimensional-isotropy of the elastic probe is carried out.A refined stiffness model of the elastic probe is established,the stiffness characteristics and displacement transfer ratios of the elastic probe are analyzed.On this basis,a 3D isotropy design method for the elastic probe is proposed.The stiffness target value is determined by the maximum Hertz contact force which works as the constraint condition,the rotation stiffness ratio and translation stiffness ratio are used as the evaluation criteria,and then the critical dimensions of the elastic probe are determined.Subsequently,an elastic probe with 3D isotropic stiffness and 3D isotropic displacement transfer ratio is achieved.The simulation results verify the effectiveness of this method.Finally,experimental setups are built to verify the measurement performances of the micro probes based on orthogonal micro-focal collimation.Experimental results show that the fiber probe based on orthogonal fiber collimation can achieve high-precision 3D micro displacement measurement with resolution of 5 nm.The elastic probe based on orthogonal micro-ball collimation can realize 3D high-precision decoupling measurement of micro displacements with isotropic measurement performance.The stiffness at its probe tip is about 23 ?N/?m,and its resolution is 5 nm.The extended measurement uncertainties of the micro holes and micro steps measurement results are 0.21 ?m and 0.022 ?m respectively for k=2.