数字全息干涉位移场分离研究

提出了一种基于窗口傅里叶脊的离面与面内位移分 离方法,应用于数字全息的多分量干涉相位场 分离。首先,物光束对称照射待测物体, 参考光束直接照射CCD靶面,由CCD相机记录物体变形前后的两幅离轴数字全息图；然后,采 用菲涅尔衍射积分法再现物体变形前后的复物光场,再由两幅复物光场共轭相 乘构建干涉场,利用幅度区分准则和窗口傅里叶变换处理复干涉场,通过窗口傅里叶脊值的 搜索,提取不 同灵敏度矢量物光对应的干涉相位分量；再对干涉相位场进行简单数值运算,将面内与离面 位移场分离出 来。最后,对周边固定、点加载、绕轴向旋转的Al制圆盘三维位移场进行实际测量。实验结 果验证了本文方法的有效性。

Study on separation of displacement field in digital holographic interferometry

A novel method based on windowed Fouri er ridge for separation of out-of-plane displacement from in-plane displaceme nt is presented and applied to the separation of multiple interference phases in digital holographic interferometry.Firstly,a single laser light source is used to illuminate the te sted object symmetrically to its surface normal,and a single reference beam is u sed in conjunction with the diffusely scattered object beams to record the hologram at the CCD plane.Two fra mes of off-axis hologram before and after object deformation are captured by CC D.Then,Fresnel diffraction integral reconstruction provides two complex object wave-fields before and after object deformation,and the interference field can be obtained by the conjugate mutiplication of two fr ame reconstructed complex object wave-fields.Windowed Fourier ridge and amplitude discrimination criteria are allowed to separate multiple interference phases which carry the information on multidimens ional deformation corresponding to the object beams with different sensitivity directi ons. Out-of-plane displacement can be separated from in-plane displacement only by simple numerical calculation of multiple interference phases.Finally,the experiment is conducted to prove the validity of the proposed method.A fully-clamped circular aluminum disk with a point load and in-plane rotation along its normal is chosen as a specimen,and i ts three-dimensioal (3D) displacements are successfully measured by the proposed method.The feasibility o f proposed algorithm is demonstrated by the experimental results.