Two-Wavelength Phase-Shifting Projection $Moir\acute{e}$ Topography for Measurement of Three-Dimensional Profiles with High Step Discontinuities

고단차 불연속 형상의 3차원 측정을 위한 이중파장 위상천이 영사식 무아레

[$Moir\acute{e}$] technique is now being extensively investigated as a fast non-contact means of three-dimensional profile measurement especially for reverse engineering. One problem with $moir\acute{e}$ technique is so called $2\pi$-ambiguity problem that limits the maximum step height difference between two neighboring sampling points to be less than half the equivalent wavelength of $moir\acute{e}$ fringes. In this investigation, a new two-wavelength scheme of projection $moir\acute{e}$ topography is proposed and tested to cope with the $2\pi$-ambiguity problem. Experimental results are discussed to assess the new method in measuring large objects with high step discontinuities.