介绍在移相式数字平面干涉仪的基础上建立的高精度数字波面扩速器技术，该技术可扩展干涉仪的测试孔径。文中介绍了数字波面扩束技术的原理，使用计算机模拟实际的测试过程，分析原理误差对波面复原精度的影响，此技术已用在２５０ｍｍ口径的移相式数字平面干涉仪上，扩束口径达５００ｍｍ This paper introduces the high precision digital wave surface diffuser technology based on the phase shift digital planar interferometer, which can expand the test aperture of the interferometer. In this paper, the principle of digital wavefront beam expander technology is introduced, the actual testing process is simulated by computer, and the influence of principle error on the wavefront restoration accuracy is analyzed. This technique has been used in the 移250mm phase shift digital planar interferometer, Up to  500mm