Design Of Flat Crystal Measurement System Based On Phase Shift Interferometer

Tranditional method to measure the flatness was absolute measurement.First way was based on the isoclinic interferometer,and then transfer the quantity to the long optical flat or milling straight edges;Second way was based on the equal-thickness interferometer,and then transfer quantity to other first or second order flat of different-sized.With decades of development of flatness metrological system,phase-shift interferometer was introduced as the measured instruments.However,the index system of phase-shift interferometer was different form the isoclinic interferometer,correlative experiment which was been organized by National institute of Metrology in China could only analyze the testing results respectively,and not come to the conclusion about compatibility and validity based on the phase-shift interferometer.This paper aims ’to focus on metrological reform to general phase-shift interferometer,improves the sampling precision and not replaces the traditional sampling index of regulation,ensures compatibility and advancementof metrology testing.This paper discusses index system of straightness and flatness,procides a hypothesis and additional requirements in the process of "point-line" and "line-plane" meausring have influence on the transitive accuracy.The auther analysises the advantage of high-resolution meausring based on PSI and establishes its leading position in quantity transfer.This paper puts forward to use characteristic section instead of arbitrary cross-section in transmission of flatness,and suggests to cancel the long optical flat to meet the qualification of flat measuring.The paper shows that transferring with sampling of 1mm based on PSI could really unify all the metrologic transduction pathways.To fill the gaps in the field of measurement based on PSI,the metrologic software called FlatEx was designed used by 3-tier construction and modularization thinking in order to meet metrologic requirements,the whole frame and the each modular design ideas was described,moreover,both UML class diagram and key algorithm or flowchart of each fucntion was provided.At last,the flat crystal was measured using absolute inspection method of three mutual inspection comparing the results of equal inclination interference,came up with a well-fitted conclusion.The milling straight edges was measured by the method of image stitching measurement and tilt measurement,and results of PV index were 0.269μm and 0.292μm.Both results were fulfill the measuring regulation.