散斑在轴向的退相关现象是制约散斑干涉测量适用性的关键问题之一，为了提高散斑场的纵向相关性，从而提高散斑干涉图像的条纹对比度，扩大物体离面形变的测量范围，提出一种对散斑场进行相位编码调制的方法，即将波前编码技术扩展景深的方法用于散斑场编码，在孔径光阑位置上放置立方型相位板实现相位调制。首先分析了该编码调制方法用于提高散斑场纵向相关性的可行性，然后基于4f 系统模拟仿真并实验验证了通过相位编码调制提高编码散斑场的纵向相关性的实际效果。结果表明，编码后散斑的纵向尺寸从0.17 mm 提高到0.4 mm，大约提高了2.5 倍。

The axial decorrelation of speckle patterns is one of the key problems which restrict the use of speckle interferometry. A method of speckle field phase encoding modulation is proposed to increase the speckle longitudinal correlation so that the contrast of the speckle interference fringes can be improved, and then the measurement range of the object surface deformation can be extended. The wavefront coding technique is used to code the speckle fields and a cubic phase mask is set at the position of aperture. The feasibility of this method in increasing the longitudinal correlation of speckle fields is analyzed firstly. The effect that the cubic phase mask in the 4f system can effectively increase the longitudinal correlation of coded speckle field is validated by simulation and experiment respectively. The results show that the longitudinal speckle size increases from 0.17 mm to 0.4 mm and increases by about 2.5 times.