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目的：比较3种滤波器在平板表面波纹度测量中的传输特性差异。方法采用2 RC 滤波器( JIS B 0610)、指数滤波器( SEP 1941)和高斯滤波器( ASME B46.1),通过频谱分析原始轮廓与不同滤波器得到的波纹度轮廓的频谱特性,对比波纹度参数差异。结果3种滤波器的幅值特性没有振荡现象,但是高斯滤波器和指数滤波器的幅值下降速度较快,高斯滤波器和指数滤波器在截止波长处的幅值下降50%,2 RC滤波器在截止波长处的幅值下降25%。高斯滤波器和指数滤波器属于无相位移动滤波器,2 RC滤波器属于有相位移动的滤波器,在截止波长位置的相位移动约为1.05。在相同的截止波长下,指数滤波器与高斯滤波器的传输特性完全一致。进一步研究表明,采用2 RC滤波器得到的波纹度参数W a比采用高斯滤波器得到的高0.1μm。结论高斯滤波器和2RC滤波器均无法同时完全抑制截止波长范围以外的成分而完全保留截止波长范围之内的成分。

ABSTRACT:Objective To compare difference among transmission characteristics of the three filters used in waviness measure-ment on sheet surface. Methods The three different filters were a 2RC filter, a Gaussian filter and an exponential filter, respective-ly. The spectral features of waviness profiles obtained by different filters and the primary profile were analyzed. Finally, the differ-ences in waviness parameters among different filters were compared. Results The amplitude features of all three filters had no oscil-lation, but the amplitude of the Gaussian filter and the exponential filter decreased more quickly than that of the 2RC filter. At the cut-off wavelength, the amplitude of the Gaussian filter and the exponential filter decreased by a half while that of the 2RC de-creased by a quarter. For phase characteristics, both the Gaussian filter and the exponential filter belonged to filters without phase shift while the 2RC filter belonged to filter with phase shift, and its phase shift was about 1. 05 at the cut-off wavelength. It was found that the transmission characteristics of Gaussian filter were exactly the same as that of the exponential filter at the same cut-off wavelength. Further study showed that the waviness parameter filtered by the 2RC filter was 0. 1 μm bigger than that filtered by the Gaussian filter. Conclusion Both the Gaussian filter and the 2RC filter could not exactly suppress components beyond the scope defined by cut-off wavelength and remain components within the scope.