Research On Three-dimensional Absolute Localization Transient Measurement System Based On Point-diffraction Interferometry

With the increasing measurement requirements of the manufacturing industry,the point diffraction interference（PDI）technique has been researched and developed in three-dimensional（3D）absolute positioning.On-site guideless 3D positioning is the main implementation function of a 3D absolute positioning system based on PDI technology.It has the features of high-precision,fast measurement and compact design for easy portability.Aiming at the problem that the PDI three-dimensional measurement system based on PZT phase shift is susceptible to external interference,a 3D positioning point diffraction interference system based on polarization transient phase shift is proposed to realize transient measurement.In addition,analyze and correct the field-of-view deviation that is unique to transient measurements,and analyze and correct the problem of probe misalignment.The main content of this dissertation include:The research status of PDI technology at home and abroad in 3D positioning is discussed,and the necessity of developing PDI technology in high-precision 3D absolute positioning is analyzed.The transient measurement model based on PDI is described.The 3D positioning transient measurement is realized by the newly introduced polarization camera.The mathematical theory and measuring process of the 3D measurement are discussed.It is analyzed that the misalignment between the camera plane and the probe end face will introduce additional optical path differences and system errors.A probe adjustment method based on phase difference center positioning and Zernike polynomial tilt adjustment was proposed,and numerical simulations and experiments verified that the correction method effectively eliminated system errors,and the RMS value of the displacement measuring error was less than 1.5μm.The field error introduced by the polarization phase shift in the system is discussed,and an interpolation calibration method for the phase reconstruction of point diffraction interference wavefront is proposed.The corrected RMS value of the corrected wavefront error and the measurement distance error were only about 1.32×10^-3λand 13.34 nm.For verify the feasibility of the theory,A 3D positioning point diffraction interference system based on polarization phase shift was established,and the 3D measurement results were compared with 3D coordinate measuring machine experiments.The standard error of the measurement was 4.87%,and Repeated measurement results of 3D localization on the order of submicron are obtained.