Research Of Ultra-precision Moving Displacement Measuring Experiment With Phase- Scanning Measurement Method Based On Diffraction Grating

Ultra-precision positioning and detection technology has always been a research hotspot at home and abroad.At present,in the field of precision manufacturing and precision displacement measurement,those detection methods who feature high-speed,large-range,high-resolution precision positioning include two methods: laser interferometer displacement detection system and precision grating length measurement system.The laser interferometer displacement measurement system features high precision and large range,but its environment requirements on source frequency stabilization and application are very strict,and the application cost is high,which is not suitable for widespread application.The precision grating length measuring system is less affected by the environment,features low requirements on the frequency stability characteristics of the light source,and with low application cost,and is suitable for widespread application.The system uses the grating pitch as the measurement reference.Although the stripe can be electronically subdivided to obtain higher resolution,it is limited by the grating constant and the stripe quality.In practical applications,the electronic subdivision multiple is limited,and its detection resolution is difficult to reach the sub-nanometer level.In order to improve the detection resolution of the precision grating length measurement system,based on the location detection principle of classical grating interference system,a new phase scanning displacement detection method based on diffraction grating is proposed.By adding a photoelectric sensor between the two stripes in the detection field of view,the sensor canperform a reciprocating scanning motion between the stripes in a limited width,and change the receiving phase of the stripe signal,which can theoretically achieve sub-nanometer resolution and can break the physical precision limitation from the measuring system component itself.Compared with the traditional grating signal subdivision method,the new proposed method reduces the requirement on quality of the original grating signal,and breaks the limitation on the improvement of the detection resolution by the quality of the grating signal.According to the new proposed method of phase scanning displacement detection,the discrete model of the motion equation of phase scanning system is established by Matlab simulation tool.The model is simulated,the platform for ultra-precision displacement detection and positioning experiment is built,and the experimental researches which include: the platform’s own precision detection experiment,PI stage continuity test,stripe equivalent test,single phase shift displacement test,phase scan positioning experiment,etc.The experimental results show that the proposed method can significantly improve detection resolution and positioning accuracy of the PI high-precision displacement table.Compared with the traditional grating detection and positioning method,its positioning accuracy can be improved by more than 70%.