基于背景纹影波前传感技术的气动光学波前重构与校正∗

摘要

Background oriented schlieren based wavefront sensing (BOS-WS) is a new experimental technique for measuring the two-dimensional distribution of optical wavefronts and the optical path differences (OPDs) induced by the flow-field density variations. Background oriented schlieren (BOS) is traditionally used to test the flow-field density distribution, which restricts the obtaining of useful information since the obtained density information is integrated over the optical path. The OPD is very important for predicting the optical distortion when light travels through the flow field and it is tested by BOS-WS. In order to obtain the optical distortion generated by aero-optic effect, and restore the original image from the distortion known information so as to explore a new kind of supersonic imaging guidance method, theory analysis, numerical simulation and experimental methods are used based on BOS-WS. Through theoretical analysis, the wavefront measurement method based on BOS is verified and the calculation methods of using wavefront information known to predict distortion displacement field and using known displacement field to reconstruct wavefront are explored. By numerical simulation, the error sizes and the result rationalities of one stepped integral algorithm and Southwell method on the wavefront reconstruction are compared, and through the error analysis it is proved that the Southwell method is more accurate and reasonable. By a wavefront aberration experiment carried out in the flow field above the candle flame and a lens perturbation experiment, the methods of using OPD known to reconstruct distorted displacement field and correcting image distortion by the field are creatively explored. The verification experiments show the effectiveness of the correction method.%背景纹影波前传感(background oriented schlieren based wavefront sensing, BOS-WS)是利用背景纹影技术测量光学波前二维分布的新型实验手段,可定量测量光线通过干扰场后产生的光学畸变并给出光程差。为了利用BOS-WS技术获得光线因气动光学效应产生的畸变信息,并通过已知畸变信息还原原始图像,进而探索一种新型的超声速成像制导方法,本文通过理论分析,验证了利用背景纹影技术测量光学波前的方法,探索了利用已知波前信息预测畸变位移场以及利用已知位移场进行波前重构的计算方法。通过数值模拟比较了一阶梯形积分算法和Southwell方法在波前重构上的误差大小和结果合理性,并通过误差分析证明了Southwell方法更加精确合理。通过蜡烛火焰上方流场畸变实验和透镜对波前的扰动实验,创造性地探索了利用已知光学光程差还原畸变位移场及用其校正畸变图像的方法,并通过验证性实验证明了校正方法的有效性。