小波变换减小调制度轮廓术中非线性的研究

调制度轮廓术采用条纹投影和成像共轴的系统结构，将被测物体的高度信息编码在条纹的模糊程度中，无需相位展开即可完成对复杂物体的面形测量，能有效避免阴影、遮挡和相位不连续等问题。在实际测量中，由于CCD探测器光电响应的非线性，高次频的引入直接影响调制度分布的提取，从而降低系统的测量精度。研究了小波变换应用于受到非线性因素影响下的条纹调制度提取，从信号频域角度分析并推导了该方法提取条纹调制度的表达式。在进行条纹解调时采用最佳的加权滤波窗，有效抑制了非线性因素对测量精度的影响，获得比傅里叶变换更好的重建效果，计算模拟和实验验证了该结论的正确性。

Abstract

In the modulation profilometry, the fringe projection axis coincides with the observation axis, and the height information of measured object is encoded into fringe defocus, which completes the measurement with complex surface, the problems of shadows, shutoff and phase truncating. However, in the practical measurement, extraction of modulation distribution from fringe patterns will be affected on account of high-order harmonics produced by photoelectric response nonlinearity of CCD detector, which will reduce the measurement accuracy. The wavelet transform method is applied to modulation retrieval, and the frequency-domain description analysis is deduced for the fringe pattern influenced by nonlinearity. With the advantages of local analysis and multi-resolution, an adaptive optimized filtering operation is adopted to demodulate the image, which mitigates the effect of nonlinearity on measurement accuracy effectively and obtains better reconstruction results compared with Fourier transform method, both the computer simulation and practical experiment verified the validity of the proposed method.

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钟敏, 陈锋, 肖朝. 小波变换减小调制度轮廓术中非线性的研究[J]. 激光与光电子学进展, 2017, 54(7): 071205. Zhong Min, Chen Feng, Xiao Chao. Research on the Nonlinearity Mitigation by Wavelet Transform Method in Modulation Profilometry[J]. Laser & Optoelectronics Progress, 2017, 54(7): 071205.

小波变换减小调制度轮廓术中非线性的研究

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