基于互补型格雷编码的离焦二元光栅相位展开方法

离焦投影使编码光图像黑白灰级跳变产生模糊而 造成二值化错误,导致相位级次解码 出错,影响相位展开。本文提出利用互补型格雷编码光计算相位级次,完成离焦二元光栅相 位展开。生成两种编码光序列,出现误码的位置相互交错,具有互补性。结合 两种互补性编码光图像进行相位展开,可有效避免编码光图像二值化错误所引起的误码影响 。对陡 变物体测量的结果表明,相位相对误差(RE)为1． 03％,误差峰谷值(PV)为0.24rad,均方差(RMS )为0.14rad。本文方法提高了离焦二元光栅测量精度 ,扩大了测量范围,尤其适用于陡变或不连续物体的三维面形测量。

Phase-unwrapping method for the defocused binary grating profilometry based on complementary Gray-coding structured light

The optical defocusing projection can produce low-pass filtering and decrease the high-frequency components of the binary grating.So the binary grating is used to produce sinusoidal fringe grating by defocusing projection in phase measuring profilomet ry (PMP).And the Gray-coding light sequence is projected to evaluate the orders of the wrap ped phases for phase unwrapping.However,the changes between the white and black fringes in th e Gray-coding pattern become blurry under defocused projection,which would cause some errors in the binaryzation and make some mistakes in decoding the encoded light sequence.Bas ed on the complementary Gray-coding light,a phase-unwrapping method is used for the def ocused binary grating in this paper.Two kinds of Gray-coding modes are projected onto the me asured object,and the positions of the error words are different.So the two modes are complementa ry,and can avoid the influence of error words on the phase unwrapping.A steep object is success fully measured by this method.Its mean relative error is no more than 1.03%,peak-val ly (PV) error is 0.24rad and the root-mean-square (RMS) error is 0.14rad.The presented method improves the phase unwrapping accuracy,and extends the measure ment range of the defocused binary grating profilometry.It is promising in measu ring the 3D shape of the steep or discontinuous objects.