为了避免传统针孔式点衍射干涉仪中干涉成像系统所带来的误差, 提出一种无镜成像算法, 无需干涉成像系统, 从 CCD直接采集得到的干涉图复原求解被测件面形。基于平面波角谱理论构建虚拟物像共轭关系, 由CCD处直接采集到的干涉图反演至被测件共轭位置的干涉图。仿真与实验结果表明, 提出的无镜成像算法可以有效消除干涉图边缘衍射和中心衍射条纹, 同时抑制相干噪声。采用无镜成像方法可以避开干涉成像系统的设计与加工难度, 有效地保证针孔式点衍射干涉仪的测量准确度。

In order to avoid the error introduced by the imaging system in traditional pinhole type point diffraction interferometer, a lensless imaging algorithm is proposed. The algorithm can retrieve the phase of the interferograms captured by CCD without the imaging system. On the basis of the plane wave spectrum theory, we can obtain the interferogram of the exit pupil conjugate location by constructing a virtual imaging conjugate relation. Simulation and experimental results show that the proposed lensless imaging algorithm can remove the edge diffraction fringes and the central diffraction effects in the interferogram, and the coherent noise can be eliminated as well. With this lensless imaging method, we can remove the interference imaging system in the pinhole type point diffraction interferometer which is difficult to design and fabricate. Besides, this algorithm can also effectively guarantee the high accuracy of pinhole type point diffraction interferometer.