为了给航空动平台激光通信的附面层效应校正系统提供验证条件，设计了一种基于液晶空间光调制器来模拟附面层效应的模拟器。首先，从几何光学的角度分析附面层效应，将其等效为负透镜。然后，利用计算机对不同飞行条件下附面层效应与等效负透镜焦距之间的关系进行数值分析仿真。之后在液晶空间光调制器上导入不同焦距透镜的相位灰度图以实现变焦透镜的功能，通过改变变焦透镜的焦距来模拟航空平台不同飞行条件下的附面层效应。最后通过实验验证模拟的准确性，在环境温度下，模拟附面层效应的液晶空间光调制器得到的光斑图像由红外相机拍摄，之后进行图像处理分析实际光斑大小，并与理论计算光斑大小比较，得出误差曲线图。研究结果显示，基于液晶空间光调制器模拟附面层效应引起散斑效应的理论光斑大小与实际光斑大小的均方根误差为0.043 75，验证了所提出的方法的可行性和有效性。

With the advancement of flight conditions for aerospace platforms, the impact of the boundary layer effect on space laser communication transmission is also growing. In order to reduce the influence of the boundary layer effect, corresponding correction methods must be studied. To provide verification conditions for the boundary layer effect correction system of laser communication on aerospace platforms, a simulator based on the Liquid Crystal Spatial Light Modulator (LC-SLM) was designed to simulate the boundary layer effect. This article first analyzes it from the perspective of geometric optics. It is assumed that the boundary layer is a thin layer (the inner and outer diameters are equal). The refractive index of the free flow is different from the refractive index of the boundary layer. Substituting them into the focal length formula of the lens makes it equivalent to a negative lens. Under different flight conditions, the focal length of the equivalent lens is different. Then use computer software to perform numerical analysis. Setting the wall curvature radius of the aerodynamic platform as 190 mm and the flight Mach number range as 0~5 Ma, in the case of troposphere (0~11 km), lower stratosphere (11~20 km), and upper stratosphere (20~32 km), the relationship curves are obtained between the Mach number, flight altitude, and the equivalent focal length of the negative lens representing the boundary layer effect. Research shows that as the Mach number increases, the equivalent focal length of the negative lens decreases, indicating a greater impact on the communication beam. Especially when the Mach number is small, the equivalent lens focal length changes more significantly with the Mach number. After that, the changes stabilized. In terms of flight altitude, the higher the flight altitude, the thinner the air and the lower the temperature, the boundary layer effect decreases accordingly until the equivalent lens focal length value approaches infinity, at which point it can basically be ignored.Based on the above analysis, the following is an introduction to the boundary layer simulation equipment. The core device of this simulator is the LC-SLM. The phase modulation grayscale image is obtained from the phase distribution function of the lens. The grayscale information controls the applied voltage of the LC-SLM, thereby controlling the deflection of the liquid crystal molecules in the LC-SLM, thereby affecting the response to light phase modulation. Load phase grayscale images of different focal lengths into the LC-SLM to realize the function of the zoom lens, and change the focal length of the simulated zoom lens to simulate the boundary layer effect under different flight conditions of the aviation platform. Due to the LC-SLM modulation depth is not an ideal 2π, and the relationship between the modulation depth and the loaded gray value is not an ideal mapping, the designed focal length value of the simulated zoom lens is inconsistent with the actual focal length value. Therefore, it is necessary to design and build an experimental platform to verify the accuracy of its simulation. This experiment uses a 1 550 nm laser as the light source, and emits parallel light after passing through the collimated beam expansion system. Since LC-SLM can only modulate linearly polarized light, a polarizer is added in front, and then enters the LC-SLM. The phase grayscale images of the lens focal lengths corresponding to the ten types of boundary layer effects in flight states are loaded into the LC-SLM respectively, and finally an infrared camera is used to receive and collect light spots at a close distance. There is a lot of noise in the original spot image, which will affect the accuracy of the spot size analysis. Therefore, the obtained original spot image is sequentially subjected to brightness adjustment, median filtering, threshold segmentation, morphological processing and edge coordinate extraction, and Hough transform circle fitting is used to obtain the spot centroid position and spot radius. Due to limitations of computer memory and computing power, the calculation accuracy is 0.05 pixel values. Then make an error line chart between the actual spot radius value of these ten sets of data and the theoretically calculated spot radius value. The calculated root mean square error is 0.043 75. This experiment verified the feasibility and effectiveness of the proposed boundary layer simulation method.