Study On Metrological UV Microscope Displacement Traceability And Linewidth Imaging Measurement Technology

Ultraviolet microscopy has higher measurement resolution than traditional optical microscopy because it uses ultraviolet light as illumination source,so it is widely used in micro-nano size measurement.However,the ultraviolet microscopy can't be traced directly to the international definition of unit meter.For this reason,National Institute of Metrology has developed a standard device for measuring the micro-nano geometric structure of the metrological ultraviolet microscopy.In this paper,the microscopic imaging technology and microscopic measurement technology in the device are studied in depth to realize the direct traceability of the ultraviolet microscopy.The main contents of this paper are as follows:(1)Design and build a laser interferometry system with ultraviolet standard device with real-time wavelength compensation function to realize standard device displacement measurement and traceability.Study the working principle of the UV standard device and introduce the structural composition of the standard device.Based on the heterodyne laser interferometry method,a biaxial laser interferometry system is designed.At the same time,a wavelength compensator is added to the interferometric system,and an automatic wavelength real-time compensation algorithm is designed to realize accurate measurement of the displacement of the interferometric system.(2)Design and build an ultraviolet microscope autofocus system based on the depth of focus method to ensure clear line width imaging.The wavelet transform is selected as the focus evaluation function by experimental comparison.The central region of the microscopic image is used as the focusing window,and the search algorithm combined with the improved climbing algorithm and curve fitting algorithm is proposed to complete the design of the autofocus system.(3)The optimal single-scale Retinex image enhancement algorithm and improved Zernike moment edge extraction algorithm are proposed to realize line width edge feature extraction.Based on the Retinex theory,the optimal scale Gaussian kernel function is used to estimate the illumination component,and the enhanced microscopic image with the influence of illumination is obtained.The Zernike moment template coefficients are derived,the Zernike moments are calculated,and the linewidth subpixel coordinates are obtained according to the edge judgment criteria.(4)Perform a 2?m line width measurement experiment.Matching the edge features with the interferometer measurement data to obtain the linewidth measurement value,performing 10 repeated measurements.Analyzing the error source and uncertainty of the device,and the relative expansion uncertainty is 0.0036.