The Three-dimensional Topography Measurement Based On Optical Interference Projection

Among the many three-dimensional topography,the fringe projection method has been widely used in many fields,such as industrial inspection,reverse engineering and medical diagnosis etc,because of its non-contact,high precision,high speed characteristics.In traditional Fourier transform profilometry,astigmatism projection is used,and four constraints are needed to obtain a more accurate phase and height mapping relationship,and the phase nonlinear quadratic error caused by astigmatic projection can also reduce topographic recovery accuracy.In order to reduce the influence of phase nonlinearity in less restricted conditions,a universal model based on parallel optical interference projection is established.In parallel optical interference projection,the reference phase is linear change with x,and the projection is more accurate than the astigmatic projection or oblique projection.The package phase is the key part of the optical phase method to measure the three-dimensional shape of the object,and it is an important part to reconstruct the three-dimensional shape of the object.At present,the unwrapping method based on the double-frequency heterodyne method in phase unwrapping has high measuring accuracy and rapid development speed.The traditional doublefrequency unwrapping technology using digital projection reduces its ability to identify morphology details for requiring the frequency difference of two stripes small and the distance between stripes large.In order to improve the accuracy of the phase unwrapping in the unconstrained model of the parallel optical interference projection,the two-frequency heterodyne method with wavefront modulation is used to reduce the unwrapping error.The main research contents are as follows:1)Using the knowledge of phase measurement profilometry,a universal structure model of phase and height mapping under parallel optical interference projection is established,and the expression of phase and height is derived;2)In the unconstraint model of parallel light interference projection,the angle between the two beams is adjusted by phased array to generate the desired fringe spacing,and the phase unwrapping is carried out by dual frequency heterodyne method to improve the phase unwrapping accuracy;3)Using the calibration method of zhang zheng you,the internal parameters and distortion coefficient of the camera were obtained by using Matlab,and the experimental graph was corrected to reduce the error caused by camera distortion;...