基于光线追迹仿真的自由曲面反射镜像质量管控方法研究

Optical Quality Assurance of Freeform Reflectors via Virtual Ray Tracing Simulation

摘要: 抬头显示器(HUD)自由曲面反射镜凭借其大视场角、高成像质量与紧凑化光路布局的优势，已成为智能汽车与航空座舱光学系统的核心元件。当前工业界主要采用基于面型高度误差(PV值、斜率误差)的管控方法，但此类方法仅能反映镜片几何误差的静态统计特性，无法评价误差分布趋势(如梯度突变或空间相关性)对动态光路传播的累积影响，导致具有相近PV值的镜片在实装后呈现显著成像差异。另一方面，基于光学设计系统(如Zemax、Code V)的仿真分析方法虽能关联误差与成像性能，但其依赖原始光路设计文件(包含镜片参数、光源坐标等敏感信息)，而设计文件受厂商知识产权保护难以获取，严重制约了该方法的工程适用性。针对上述问题，本文提出一种基于光线追迹仿真的HUD自由曲面反射镜质量管控新方法：通过将实测镜面点云嵌入参数化虚拟光路模型，规避对原始设计文件的依赖；同时，以屏幕投影网格畸变量取代传统高度域指标，直接量化制造误差对终端成像的偏移效应。实验结果表明，该方法可有效区分传统方法难以辨别的镜片性能差异(PV值差异2 μm的两块镜片的畸变量相差7 mm)，且无需依赖保密性设计文件，为HUD自由曲面反射镜的质量管控提供了高精度、强泛化性的解决方案。

Abstract: The freeform reflector in head-up displays (HUD) has become a core optical component in intelligent vehicles and aviation cockpits due to its wide field of view, high imaging quality, and compact optical path layout. Current industrial quality control methods predominantly rely on height-domain error metrics (e.g., PV [Peak-to-Valley] values and slope errors), which only reflect static statistical characteristics of geometric errors. However, these methods fail to evaluate the cumulative impact of error distribution trends (e.g., gradient discontinuity or spatial correlations) on dynamic light propagation, leading to significant imaging discrepancies between mirrors with similar PV values after installation. Meanwhile, optical design software-based simulations (e.g., Zemax, Code V) can correlate manufacturing errors with imaging performance but depend on original optical design files (containing sensitive parameters like mirror coefficients and light source coordinates). Restricted by intellectual property protection, such files are rarely accessible, severely limiting the engineering applicability of these methods. To address these challenges, this paper proposes a ray tracing simulation-based quality control method for HUD freeform reflectors. By embedding measured mirror point clouds into a parameterized virtual optical path model, our method eliminates dependency on proprietary design files. Additionally, it replaces traditional height-domain metrics with screen-projected grid distortion quantification to directly evaluate the imaging offset caused by manufacturing errors. Experimental results demonstrate that this method effectively distinguishes performance differences imperceptible to conventional approaches (e.g., a 7 mm distortion gap between two mirrors with only 2 μm PV difference) while requiring no confidential design files. The proposed solution offers high-precision and generalizable quality control for HUD freeform reflectors.