大通光孔径气动窗口光学特性研究

Determination of optical characteristics of aerodynamic window with big exit aperture

实验研究了引射式大通光孔径气动窗口光学特性。由哈特曼激光光束诊断仪采集的数据给出了激光束通过气动窗口后的Strehl比 ,波像差 ,Zernike多项式各系数。从这些光学特性参数可以分析引射气压、气动窗口结构对通光光束质量的影响。研究表明随引射气压增加使通光光束发散 ,这和环形喷嘴喷出的气流形成的轴向气体密度分布的梯度变大有关。非均匀分布的抽口使波阵面偏斜 ,这会使光束漂移。

The optical characteristics of jet injecting aerodynamic window with big exit aperture have studied experimentally. The Strehl ratio, wavefront aberration and coefficients of Zernike polynomial of laser beam, passed through the aerodynamic window, were given up from the data, collected by HARTMANN diagnostic apparatus. From these optical characteristics it can be analyze, that the injection flow pressure and the structure of aerodynamic window influence on the passed beam quality.It was shown that the passed beam will be divergence, as the injection flow pressure becomes large. It is related to that the axial grads of air density distribution, caused by gas flow from circular nozzle, become large. And heterogeneous distribution of air bleed hole makes the wavefront tilt so that the passed laser beam will shift.