Design and characterization of band-pass filters in Fourier Transform Profilometry for accurate 3-D surface measurement

The article designs and characterizes various band-pass filters in Fourier Transform Profilometry (FTP) for improvement of 3-D measurement accuracy. A commonly challenging problem still encountered by FTP particularly lies on its unreliable extraction of precise spectral information from the spectral domain. Thus, comprehensive studies on band-pass filtering were performed to investigate the filter design and its impact on quality of geometric shape reconstruction. From the experimental results, it is confirmed that the measurement accuracy of dimension and sphericity can be greatly enhanced over 3 folds when the newly proposed filter is compared with the traditional circular bandpass filter. The maximum measured dimensional error can be controlled within 1.25% of the overall measuring size.