改进型非相移的傅氏变换轮廓测量法

为提高傅氏变换轮廓法 (FTP)的最大可测梯度 ,改进了一种不需移相就能去除零次分量的新方法。通过额外产生零次分量并将其从畸变栅线频谱中去除 ,可使主频带在低频段得到很大扩展。同时控制 Ronchi光栅散焦 ,可有效抑制空间高次谐波。该方法建立的光学模型符合实际测量情况 ,据理论分析可将最大可测梯度提高至原来的 3倍。较之以往通过精确相移滤除零次分量的方法 ,该方法更易实施

Improved Fourier transform profilometry with non-phase-shifting method

In Fourier Transform Profilometry (FTP), the maximum gradient that can be measured is limited due to the overlap between the principle component and other harmonic components. An improved method is presented to filter the zero and higher components. The zero component is subtracted from the spectrum of the deformed grating pattern to greatly extract the principle component at low frequencies. The higher components are greatly weakened by defocusing the optical field of the Ronchi grating. Theoretical analysis shows that the improved FTP method can extend the maximum measurable gradient to nearly three times that measured using standard methods. Experiments also show that this new method agrees well with measured results. The method can be much more easily implemented than methods which use phase shifting.