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粗糙表面在多波长激光束照射下形成的多色散斑场显示出散斑延长效应,利用此效应可以测量表面粗糙度,并且测量结果在一定条件下不受粗糙表面横向特征的影响。通过模拟计算随机粗糙表面的多色散斑场,以空间平均的多色散斑场局部自相关函数研究了平均散斑延长率〈χ〉对表面轮廓均方根偏差σh的依赖关系,分析了测量系统因素,如入射激光波长组合、成像器件光敏单元尺寸和动态范围对测量结果的影响。结果表明,以空间平均的局部自相关函数代替集平均的散斑自相关函数描述多色散斑延长效应是有效的;为达到一定的粗糙度测量精度,应选择合适的入射激光波长组合和合适的成像器件光敏单元尺寸。
The multi-color speckles field formed by the multi-wavelength laser beam on the rough surface shows the speckle extension effect, and the surface roughness can be measured by this effect. The measurement results are not influenced by the lateral characteristics of the rough surface under certain conditions. The dependence of the average speckle extension on the root mean square deviation (σh) of the surface profile was investigated by means of the local autocorrelation function of the multi-color speckle patch in a space-averaged manner by simulating the multi-color speckle speckle in a random rough surface. The measurement system Factors, such as the incident laser wavelength combination, the size of the photosensitive element and the dynamic range of the imaging device, affect the measurement results. The results show that it is effective to describe the effect of multi-speckle speckle extension by replacing the set of average speckle auto-correlation functions by the local average autocorrelation function of spatiotemporality. In order to achieve a certain accuracy of roughness measurement, a suitable combination of incident laser wavelength and suitable Imaging device photosensitive cell size.