Modified fourier transform profilometry for the measurement of 3-D steep shapes

Analysing the principle of Fourier transform profilometry (FTP) for the measurement of 3-D object shapes and improved Fourier transform profilometry (IFTP) for the measurement of 3-D steep object shapes, the disadvantage of IFTP is discussed. Through the measurable slope of the height variation normal to grating line can be extended to nearly three times in IFTP, and phase-shift error is introduced. In this paper modified Fourier transform profilometry (MFTP) is described for the measurement of 3-D steep object shapes, which gets rid of the disadvantage of IFTP by utilizing the nature of FTP. The measuring precision and the measureable steepness can be ensured in this way.