Research On 3-D Profilometry Technology Based On Two Grating Stripes Fringes

The 3-D profilometry technology has a plenty of practical value in actual life,industrial manufacture and medical science for it's advantages of Full measurement, short time-consuming and higher precision. In the 3-D profilometry technology,phase-shifting profilometry algorithm or Fourier transform profilometry algorithm are the most basic two kinds of the method.the phase-shifting profilometry algorithm use more than three phase modulation images to constitute a group of equations,and then get the phase,so it don't adapt to dynamic measurement.The Fourier transform profilometry algorithm use just one modulated fringes to get the phase through separating the different frequency of grating stripe.however it has some problem like Frequency spectrum leakage, spectrum separation and the selection of filtering window function.The algorithms of this paper need just two fringes and can measure the moving objects with low requirements of the systems.The main contents are as follows:1>Introduce the background of the basic theories of 3-D profilometry technology and the two step phase-shifting algorithm.first Remove the DC component of the phases and then extract the phase through the two fringes by the method of known.and it was proved by theory and practical measurement.what's more we find the disadvantages and provide the future research foundation.2>Introduce an improved two-step phase-shifting profilometry algorithm, the background and the modulated phase are extracted by least squares parameter estimation method which can also regularize the modulated fringes.Then use the statistical properties of the fringe to calculate the corresponding phase.Finally the proposed method was testified by simulation and actual measurement.3>Introduce the EMD algorithm with adaptive frequency decomposition, use the time characteristic scale of the date,first detect the high frequency component by small time scale,then detect the low frequency component by large time scale and so on until get the rest of the flat component.combine the EMD filter with the two-step phase-shifting algorithm.Then the two step phase-shift algorithm based on the EMD filter is simulated and authenticated by the actual measurement.4>Introduce the fast image moire method,this method needs just two fringes,one with the object and the other with background.First remove the DC component of the phases,then multiply by the two picture,finally get the information of object by filtering.the fast image moire method was verified by the simulation and actual measurement.Then Introduce the fast image moire method basic on EMD.there is no need to filter the dc component,the method use just two fringes too and was verified by the simulation and actual measurement.5>3D shape measurement software was designed and developed,and it was proved by actual test.