Selecting an appropriate pitch is one of the most important aspects to ensure the system measurement range and precision in grating projection principle of 3D profile measurement while the Fourier transform frequency spectrum is separated completely. According to the concept of the equivalent wavelength, the basic requirement for measurement system and the selection of projection grating pitch are discussed in this paper to avoid shadows and frequency spectrum alias in a crossed-optical-axes system in Fourier Transform Profilometry (FTP). The influence of CCD sampling to the FTP is also discussed to obtain CCD sampling condition. When the CCD sampling frequency is unchanged, it is necessary to reduce the grating frequency which means to increase the grating pitch to satisfy the sampling condition. Finally, the range of the grating pitch is determined, and the optimal grating pitch is obtained after the experiments.

Date Published: 30 November 2009
PDF: 8 pages
Proc. SPIE 7506, 2009 International Conference on Optical Instruments and Technology: Optical Systems and Modern Optoelectronic Instruments, 750629 (30 November 2009); doi: 10.1117/12.838399

Published in SPIE Proceedings Vol. 7506:
2009 International Conference on Optical Instruments and Technology: Optical Systems and Modern Optoelectronic Instruments
Yongtian Wang; Yunlong Sheng; Kimio Tatsuno, Editor(s)