小波相位解调轮廓术

针对傅里叶变换轮廓术因混频难以准确提取基频的问题,可将小波变换用于三维形貌相位直接解调。对其原理进行了研究,通过编程实现了小波相位解调。取Morlet复小波作为小波母函数,对调制栅线图逐行进行连续小波变换,从各位置的沿尺度方向的小波变换系数幅值的极值中可直接求取对应的相位数据。由于小波函数具有空域_频率两域的局部化特性,因此它对变形栅具有很强的自适应能力。为验证新方法,对其进行了仿真分析,同时还对石膏半球模型和化妆品瓶进行了实际测量,并分别用傅里叶变换和小波变换进行了处理。结果表明,新方法有效地克服了混频的问题,改善了相位解调效果,提高了测量精度,特别适合于复杂物体的形貌测量。

Profilometry of phase demodulation using wavelet transform

In order to resolve the problem of restoring the fundamental component exactly from frequency aliasing in Fourier transform profilometry(FTP),wavelet transform is introduced into phase demodulation,which is studied,whose theory is deduced in detail and the procedure is realized by programming.Morlet complex wavelet is used as mother wavelet,continuous wavelet transform is applied to deformed grating image along each row,the maximum magnitude of wavelet transformation coefficient in each position is established along scale direction,which is used to retrieve the phase value in phase distribution image of wavelet transform.The new method has self-adaptability for the variation of deformed grating frequencies.To validate the new methodology,the evaluation is performed using the computer-simulated grating.The experiments with plaster hemishere model and cosmetic bottle are provided,which are processed and analyzed by FTP and proposed method respectively.Results demonstrate that the limitation can be eliminated,the effect of demodulation is improved apparently,the accuracy is enhanced and it is able to fit for measuring complicated object.