The Design Of 2-D Dynamic Photoelectric Microscope

Based on the principle of photoelectric conversion,the dynamic photoelectric microscope can achieve high precision dynamic aiming for the line pattern,which has the advantages of high aiming precision,fast alignment speed and non-contact measurement.With the development of mechanical manufacturing level,two-dimensional photomasks are widely used in the calibration and evaluation of high-precision instruments such as image measuring instrument and coordinate machine.It is of great significance to realize the high-precision calibration of two-dimensional line scale and promote the development of line measurement scale from one dimension to two dimensions.In order to realize the high-precision traceability measurement of two-dimensional photomask and solve the key problem of high-precision alignment of two-dimensional line scale,based on the working principle of one-dimensional dynamic photoelectric microscope and length comparator at home and abroad,a two-dimensional dynamic photoelectric microscope aiming system applied to laser interference length comparator is designed to realize the high-precision calibration of two-dimensional line scale.Firstly,the overall design requirements of the two-dimensional dynamic photoelectric microscope are determined.The specific design scheme is proposed of the optical system,photoelectric conversion module and mechanical adjustment structure of the photoelectric microscope.Then the optical system of 5~×,10~×,20~×objective lens,lighting optical system,video observation system and light splitting system are designed by using optical design software.The formula of light flux at the slit is deduced when different slits are adapted to different lines.The matched optical slits are designed for the lines with different shapes and specifications,so that the output signal of the photomultiplier tube by photoelectric conversion has better signal-to-noise ratio and sensitivity.Based on the results of optical system design,photoelectric conversion module is formed of high sensitivity photomultiplier tube and preamplifier circuit.According to the structure of the length comparator and the optical path of the microscope,the mechanical structure design is completed.In the process of actual installation and adjustment,the design result can meet the adjustment requirements of the splitter prism,optical slit,object lens tube and so on,so as to ensure the accuracy of the system.And the whole processing,assembly and adjustment of the microscope are completed.Finally,in order to verify the dynamic aiming ability of the two-dimensional photoelectric microscope,a dual frequency laser interferometric length measurement system is built,and the aiming repeatability of one-dimensional glass ruler and two-dimensional grating template is tested by using a high-precision two-dimensional displacement platform.The experimental results show that the aiming accuracy of two-dimensional dynamic photoelectric microscope is better than 0.1?m in X and Y directions of one-dimensional glass ruler and two-dimensional grating template,which satisfies the design requirements of the system.