基于参考物镜的数字全息显微相位畸变自动补偿

Automatic Compensation of Digital Holographic Microscopic Phase Distortion Based on the Reference Objective

建立了参考物镜与数值拟合相结合的方法对离轴数字全息显微系统的相位畸变进行补偿.因为物镜带来的光波曲率差异预放大数字全息显微系统往往产生附加相位因子.在参考光路中引入相同参考物镜利用物理方法初步消除因为曲率问题带来的相位畸变.参考物镜加入以后相位畸变主要来自三个方面.衍射计算时使用数字模拟平面参考光离轴结构存在空间角产生一次相位畸变实际记录到的全息图参考物镜实验误差导致了残余二次相位畸变光路中其他光学元件形成像差无法获取正确的微结构三维形貌.数值上通过多项式对整个相位表面作曲面拟合利用相位表面与该拟合曲面的差值提取样品真实相位分布.只用一幅全息图经过一次多项式拟合便实现了多次相位畸变的自动补偿.以USAF分辨率板作为微结构样品作形貌测量验证了该方法的准确有效.

The method of combining reference objective and numerical fitting is established to solve the phase distortion of off-axis digital holography. Because of the optical curvature difference caused by the objective, the pre-amplified digital holographic microscopy system often produces additional phase factors. By introducing the same reference objective in the reference beam path, the phase distortion due to curvature problems is initially eliminated. With the addition of the reference objective, phase distortion mainly comes from three aspects: the numerical simulation of plane reference light is used in diffraction calculation, and a phase distortion is generated with the off-axis structure having a spatial angle;the actually recorded hologram causes a secondary phase distortion because the object wave passes through the pre-amplified objective;the other optical components in the optical path form aberrations, failing to get the correct 3D shape of the microstructure. The entire phase surface is fitted by a polynomial, and the difference between the phase surface and the fitted surface is used to extract the true phase distribution of the sample. With only one hologram, multiple phase distortions are automatically compensated by a polynomial fit. The USAF resolution plate being used as the microstructure pattern for measurement,the accuracy and effectiveness of the method are verified.