Key Technology Study On Single-axis Normal-tracking Measurement System

As the demand for the high-precision surface-type components in various fields keeps growing along with the development of science and technology,high-precision measurement of large curved surface has been overseas and domestic research focus.According to the present situation,a single-axis normal-tracking measurement system was proposed.The single-axis normal-tracking measurement is based on the non-contact laser differential confocal probing technique,in which the automatic alignment system and servo feeding system are added.The automatic alignment system and servo feeding system make the included angle of optical axis of the measuring system and surface under test be adjusted real-time,while the problem that traditional differential confocal system is not applied to a great tilt angle of surface under test can be solved.The aim of this research is to finish the resolution indicator of the single-axis normal-tracking measurement system.The theoretical model of the differential confocal system with the Gaussian beam is deduced,which shows the difference between the theoretical model with the Gaussian beam and the point source.The theoretical model of the servo-driven part of the single-axis normal-tracking system is presented,which further proves the feasibility of single-axis normal-tracking measurement system.Based on this research,the pinhole parameters influences the resolution of system are analyzed theoretically,and also the optimal size and optimal offset distance of pinhole are obtained.By theoretical analysis and numerical simulation,the tilt dependent error of the measurement system and the influence of error were studied.The optimal size of the pinhole is obtained through MATLAB numerical analysis under the condition of laboratory specific parameters.The optical path was selected and built.The resolution of experimental optical path is verified,and it proves that the axial resolution of measured part has reached 5nm.