Abstract：Spectral confocal displacement measurement (SCDM) is an important part of precision measurement, which is of great significance to precision manufacturing. However, the traditional scanning spectral confocal measurement system has the interaction between different confocal points, which severely limits the measurement resolution. In order to overcome this limitation, this study proposes a new displacement measurement method, which maintains the independence between multiple measurement channels through fiber optic bundle, switches the measurement channels through optical switches to prevents Interference. There are seven measurement channels in total, and each measurement channel corresponds to a confocal point. After final calculation, 7 confocal points together form an equilateral hexagon, 6 points are at the 6 vertices of the hexagon, 1 confocal point is at the center of the hexagon, and the side length of the hexagon is 43.27μm. Through the displacement measurement experiment, it is concluded that the absolute error of each measurement channel of the displacement measurement system is less than 0.15μm, and the range is 0~90μm. In the experiment of measuring the difference in step height, two step surfaces with a height difference of 30μm were measured, and the error of the final result was at most 0.16μm. In the sphere radius fitting experiment, seven channels of data can be measured without mechanically moving the measurement system or the measured object. The approximate value of the radius of a sphere with a radius of 5mm is obtained by fitting the data, and the maximum error is 80.92μm, which shows that the new method completely breaks through the limitations of the traditional method. Experimental results show that the method proposed in this study can effectively improve the resolution and precision of SCDM.
2024, Vol. 45 
