| With the improvement of Industry 4.0’s requirements for manufacturing quality and change of technological,new challenges are presented to modern photoelectric sensing technology in the field of precision geometric measurement.Among them,the chromatic confocal displacement measurement has the characteristics of high precision,anti-interference and non-mechanical axial scanning,and gradually becomes the representative direction of new displacement sensor measurement.In order to achieve the depth of recognition,this method need to be calibrated the relationship between wavelength and the displacement,and extracted the peak wavelength of the sample surface from the reflected light signal,then the corresponding displacement or height will be calculated through dispersion relations.Therefore,it is of great significance to study the essential principle of chromatic confocal displacement measurement system and the key technology of signal processing.The main research contents of this paper are as follows:(1)The background and significance of chromatic confocal measurement technology as well as the research status are discussed,and the necessity of studying the key techniques of chromatic confocal displacement measurement is determined.The optical design principle of chromatic confocal displacement measurement system is analyzed theoretically,and the main factors affecting the measurement accuracy are summarized.(2)A set of chromatic confocal displacement measurement system based on diffractive optical elements is designed.The advantages and disadvantages of refractive optical elements and diffractive optical elements as dispersion lens are compared through simulation analysis.The diffractive optical elements with good linear dispersion effect are selected as the core elements of displacement measurement to realize wavelength modulation of displacement.(3)A spectral data processing method based on Savitzky-Golay filtering and Gaussian fitting is proposed,which can effectively locate the spectral peak and extract the peak wavelength accurately,and achieve the high-precision extraction of the measured signal features.(4)The construction of the chromatic confocal displacement measurement experiment system is completed.The calibration system structure in accordance with the principle of calibration and installation is designed.The laser interferometer with higher accuracy is used to calibrate and measure the system.The error analysis and significance test of the experimental results are carried out.The analysis and compensation of random error and system error are given to determine the measurement accuracy of the system.The experimental results show that: the measurement range of the system is 0-4mm in the wavelength range of 500-700 nm,and the measurement error is within ±8μm.The measurement system has high precision. |
