摘要
为了解决在光学设计后期车载镜头难以在保持高分辨率的同时校正大视场光学系统畸变的问题,基于逐点构建的设计思路提出一种利用自由曲面校正车载镜头畸变且保证一定分辨率的方法。基于Snell定律,利用光线追迹的方式将光学系统畸变和出射光线关联,对从出瞳发出的不同视场的主光线和不同孔径光线同时偏折,在保证一定分辨率的同时校正光学系统的畸变。通过逐点构建方法求解特征数据点坐标后,利用MATLAB软件拟合自由曲面轮廓,得到XY多项式系数。将得到的自由曲面透镜与满足分辨率要求但存在畸变的车载镜头相结合,通过Zemax软件进行仿真实验,结果显示,畸变明显下降,且保持了一定的分辨率要求。对车载镜头优化后,在92.08°×60.66°的大视场下系统的光学畸变从-10.00%降低到0.68%,TV畸变从-6.58%降低到0.01%以下,并且提高了系统的调制传递函数(MTF),足以匹配800万像素传感器。同时,还进行了相同位置处的自由曲面和非球面横向对比,对比结果体现了自由曲面在车载镜头中的优势,在畸变和MTF方面有着更好的表现。此外,对自由曲面车载镜头进行了不同视场的公差与良率分析,对球面、非球面和自由曲面分别采用叠加曲率、叠加泽尼克系数、加入面形PV的方式对面形公差进行分析,结果表明,在频率为59.5 lp/mm处平均MTF大于0.55的概率为90%,说明该系统易于加工与装调。
Objective Currently, automotive lenses are advancing towards high resolution, wide viewing field, and low distortion.High resolution and wide viewing fields enable automotive lenses to capture clearer and broader images. However, these advancements often lead to increased optical distortion within the system. Given the critical role of autonomous driving in personal safety, addressing distortion issues is paramount as they can compromise image quality and thereby affect the safety of autonomous driving. Moreover, existing real-time correction algorithms for image distortion are not fully developed. Therefore, addressing this issue at the hardware level presents a more stable solution. Currently, the automotive lenses available on the market primarily employ aspherical designs for distortion correction. However, the ability of aspherical lenses to handle distortion still lags behind that of freeform surfaces. Aspherical lenses require more complex element arrangements and pose challenges in determining optimal positions, leading to increased manufacturing and design complexities. In contrast, freeform surfaces offer greater design flexibility, making them more effective in correcting aberrations and controlling distortion. Within coaxial optical systems, two primary design methods exist for the initial structure of freeform surfaces. One method involves progressive optimization, which imposes stricter requirements on surface shapes and offers limited distortion correction capabilities. The other method involves deflecting chief rays emitted from the exit pupil, while this approach compromises image quality and fails to meet high-resolution demands.Therefore, based on the theory of point-by-point construction, we propose a freeform surface design method that deflects both chief rays and various aperture rays to address distortion in automotive lenses while meeting high-resolution requirements. This approach enables the design of automotive lenses with higher resolution, wider viewing fields, and low distortion suit
作者
丁岩
张乃文
杨超
薛常喜
Ding Yan;Zhang Naiwen;Yang Chao;Xue Changxi(School of Optoelectronic Engineering,Changchun University of Science and Technology,Changchun 130022,Jilin,China;Key Laboratory of Advanced Optical System Design and Manufacturing Technology of Universities of Jilin Province,Changchun University of Science and Technology,Changchun 130022,Jilin,China)
出处
《光学学报》
EI
CAS
CSCD
北大核心
2024年第14期223-233,共11页
Acta Optica Sinica
基金
吉林省自然科学基金(20220101124JC)。
关键词
光学设计
车载镜头
自由曲面
逐点构建
畸变
高分辨率
optical design
automotive lens
freeform surface
point-by-point construction
distortion
high resolution
