气流扰动将引起干涉检测光路中空气折射率动态变化, 从而引入未知波前测量误差, 它对于大口径、长焦距光学系统波前检测精度的影响尤为严重。为抑制该影响, 本文提出一种基于计算流体动力学的主动温度场控制方法。首先, 分析了气流扰动引入波前检测误差的原因, 并基于流体力学理论阐明了通过主动送风手段提高室内温度场均匀性、抑制气流扰动影响的可行性。其次, 结合口径为500 mm、焦距为6 000 mm的离轴三反望远镜检测光路构成以及所处环境条件, 通过Fluent软件仿真建模提出一种利用风扇阵列主动送风的室内温度场控制方法。最后, 对温度场控制前后实际光学检测数据进行对比, 结果表明, 控制前后7组像差系数测量值(一段时间内多次测量平均值)之间的标准差由0.034λ减小到0.005λ(λ=632.8 nm)。本方法可有效抑制气流扰动对于光学检测精度的影响, 对于提高非真空条件下大口径光学系统的波前检测精度具有一定的参考与借鉴意义。

Airflow disturbance can cause a change in the air refractive index, which will introduce an unknown wavefront measurement error, especially for large-aperture, long-focus optical systems. To suppress this effect, this paper proposes an indoor temperature field control method based on Computational Fluid Dynamics (CFD). First, the cause of the wavefront detection error induced by air disturbance is analyzed, and the feasibility of improving the uniformity of indoor temperature field and restraining the influence of air disturbance using active air supply is expounded based on hydrodynamics theory. Secondly, an indoor temperature field control method using fan array for active air supply is proposed through simulation modeling, which considers the composition of the self-collimation optical path of an off-axis Three-Mirror Anastigmatic (TMA) telescope (diameter of 500 mm, focal length of 6 000 mm) and the environmental conditions. Finally, the actual optical measurement data before and after temperature field control are compared to verify the effectiveness of the proposed method. The results show that the standard deviation among the seven groups of aberration coefficient measurements (mean values of multiple measurements over a period of time) decreased from 0.034λ to 0.005λ(λ=632.8 nm). The proposed method can effectively suppress the influence of airflow disturbance, which has certain reference significance for improving the optical detection accuracy of large-aperture long-focus optical systems under non-vacuum conditions.