大气高阶扰动对傅里叶望远镜成像的影响分析

傅里叶望远镜（FT）综合了激光主动照明和合成孔径的优点，采用相位闭合技术可以消除各发射望远镜间的粗大相位差及大气的低阶扰动对成像的影响，分辨率可突破单一望远镜的衍射极限。为了FT 实际工程系统的实施，需探讨大气高阶扰动对FT 成像质量的影响，文中模拟大气高度36 km，通过等Rytov 指数方法将大气分成40 层并计算得到了每层的上下界限及每层相位屏的高度值。对于3333 T 型均匀间隔发射阵列，每层模拟了1 626 个相位屏。光束传输采用夫琅和费衍射近似。通过计算机模拟，在不考虑噪声的情况下，对于10 cm 的发射口径，得到大气高阶扰动对FT 成像质量有微小影响的结论。重构结果与衍射极限图像的斯托里尔比（Strehl）由无大气时的0.682 1 降低到0.623 6。当信噪比为100 时，Strehl 达到0.452 5，可分辨目标。

High modes disturbance of atmosphere on the Fourier telescopy imaging analysis

Fourier telescopy (FT) is an imaging method that combines the advantages of active laser lighting and synthetic aperture. Using the phase closure technique can eliminate the coarse phase of two arbitrary launch telescopes and the effects of atmospheric low-level disturbance. The resolution of reconstructed image can overcome the diffraction limit of a single telescope. For the realization of the engineering systems of the Fourier telescopy (FT), the image quality was explored when the light via the atmosphere with 36 km atmospheric height. The atmosphere was divided into 40 layers by the Rytov index method; the upper and lower boundaries of each floor and the heigth of each phase screen were calculated. To the 33 33 T-type emitter array with uniformly spaced, the number of simulated phase screens was 1 626. Fraunhofer diffraction approximation was used when beam from the emitting surface to the target. Through computer simulation, without considering the noise, for the 10 cm emission caliber, we obtain the conclusion that the higher order disturbance of atmosphere has a slight impact on the FT imaging system. Without the atmospheric high order disturbance, the Strehl of reconstruction image and diffraction limit image is 0.682 1. With that the Strehl is reduced to 0.623 6. When the signal to noise ratio of 100, the Strehl reach 0.452 5, and the target can be discriminated.