The Research Based On Projected Various Fringes For Curved-SurfaceMeasurement

The size and 3-D contour are important information of an object. In the recent years,the three dimension profile measurement technology has been developed quickly and applied widely in industry,agriculture, biomedicine and many other fields. As a branch of it ,the structure light measurement technology, with its special advantange of non-touch, higher accuracy, easy to realized and etc, has been put on wider and wider emphasis and become the common method in this field. Several methods of those, such as moirétechnique, Phase Measuring Profilometry (PMP), Fourier Transformation Profilometry (FTP) have been exhaustively studied in these years. Unwrapping the phase reliably and improving the precision are the hot points in the PMP research. My dissertation focuses on these two issues, and the major work can be summarized as follows:1.A method to obtain absolute phase directly based on projected various spatial frequency fringes has been deduced. By analyzing the relationship between the orders and phase of the three fringes, we can get the absolute phase from decimal orders of those three spatial frequency fringes, without unwrapping. This method can meet different experimental requirement since it nearly has no limits on fringes frequency.2.To extract the phase values exactly, a method which based on eight-step phase shifting technique was used.Compared with the traditionally four-step phase shifting technique, the experimental result showed the phase error was reduced greatly, a good result can be obtained.3.The Moire effect in fringe projection was investigated. The experiment indicated that Moire effect could be decreased through adjusting the light route and properties of DLP and CCD. The conclusion was very useful in minimize the Moire effect and improve experiment precision.