Telecentric Three-dimensional Measurement Shape Technology Based On Single Fringe Projection

In recent years,Optical detection technology based on telecentric imaging has been widely applied in precision measurement industry,such as machinery manufacturing,electronics,materials,etc.The method of using fringe pattern to obtain the surface shape features has become popular in the field of active optical measurement.Combined with the characteristics of telecentric imaging and stripe projection technique,this paper mainly studies telecentric three-dimensional(3D)shape measurement technology based on single fringe projection,in purpose to use a single defocused fringe patterns quickly achieve a full 3D reconstruction for the object.Meanwhile,to achieve a large depth range of measurement,this paper do some relevant research in the bilateral telecentric depth of field,depth of field error of the systems and exceeding depth of field error analysis.The paper's main contents are following:The characteristics of bilateral telecentric optical path and telecentric imaging model are introduced in this paper.Setup the telecentric single fringe projection 3D shape measurement systems.S-Transform simplify extracted the wrapped phase map and applied method for phase wraps elimination complete the phase-height calibration experiment,measuring a standard height object,the relative error of 0.40%.The standard deviation of the adjacent two center distances of the calibration in the XY plane is 1 ?m.A method of phase wraps reduction for achieve rapid 3D measurement is presented in this paper.That is Zero Padding Frequency Shift(ZPFS)method.The most important of the method is Zero padding the two ends of the wrapped phase's complex array and utilizing the frequency-shift characteristics of two-dimensional discrete Fourier transform pair to solve.Experimental results demonstrate that the presented method is feasible,while the contrasting technique still has residual wraps.Then combined with the result of XY plane calibration,achieved a full 3D shape in our systems.Detailed derived theoretical formula about depth of field of the bilateral telecentric imaging system,then calculated the depth of field and determined the range of depth of field under this system.Analyze the error of the depth of field and beyond the depth of field measurement in the XYZ direction.The analysis shows that the standard deviation in the XY plane measurement is basically around 3 ?m within the measuring range.Performing the depth error compensation in the Z direction with a larger error.Finally,the experimental results show that maxim?m depth error after compensation is reduced to 6 ?m.