近场分布光度测量在LED汽车灯具研发中的应用

周超  王大健  李倩  潘建根

远方光电科学研究院

摘要：近年来，LED光源凭借其节能、寿命长、耐用且响应速度好等优势在汽车内外照明领域取得了广泛应用。由于涉及到安全，汽车灯具尤其是前照灯必须要经过精密的光学设计，以保证最终的配光性能。基于LED光源的特殊性，LED车灯的二次配光设计要比传统车灯复杂得多。现有的汽车灯具的研发设计中，所采用的光源光强分布数据往往由远场测量获得，即在测量距离足够远可将光源是为点光源的情况下获得的分布数据。而实际上，LED光源在近距离和远距离的光分布情况存在显著差异，基于远场光分布数据而分析的近距离反射透射等光学现象会与实际情况相去较远，给研发设计带来较大困扰。另一方面，传统远场光强分布的测量距离很长，以前照灯为例，需要30m，这样的空间距离对研发部门来说比较难以实现。因此在LED汽车灯具中引入近场分布光度是比较好的解决方案。近场测试是将光源看成面光源研究其实际发光情况，并且通过光线追踪，在很短的测试距离就能够准确获得完备的光线模型，并分析出在任意距离下的光分布情况，大大提高LED汽车灯具的设计质量和效率。本文介绍了近场分布光度测量在车灯研发中的必要性，详述了近场分布光度测量的解决方案，包括了亮度、光强和颜色分布等多个方面，并且分析了车灯研发对近场分布光度计的具体要求以及测量实例。

关键词：LED汽车灯具；远场测量；近场测量；近场分布光度计

The Application of Near-Field Lighting Distribution Measurement in LED Automotive Luminaires

Chao Zhou  Dajian Wang  Qian Li  Jiangen Pan

EVERFINE Institute of Optoelectronics

Abstract: Due to the features of energy conservation, long lifetime, durability and high response speed etc., the LED sources have played a more and more important role in the internal and external automotive lighting in recent years. To guarantee an optimized lighting distribution for safe driving, the LED automotive luminaires, especially the headlight, require precise optical design. The second optical design for LED automotive luminaires is more sophisticated than traditional automotive luminaires because of the uniqueness of LED sources. In current designs and researches, the data are acquired by far-field measurement, which processes the source as point light source because of the long measurement distance. However, there is an obvious difference between the near-field and far-field distribution. When using far-field distribution data, analysis of near-field optical phenomenons like reflection and transmission will deviate away from the fact. It brings significant difficulties in research and design. Meanwhile, the measurement distance for far field distribution is too long to be realized in many research center, usually 30m for the headlight. Thus, it is a good solution to make use of the near-filed measurement in LED automotive luminaires. The near-field distribution measurement processes the LED source as a panel source and can provide accurate ray mode through the light tracing in a short measurement distance. Furthermore, it will deduce the lighting distribution at any distance, and improve the design quality and efficiency. The paper introduces the necessity of near field measurement in automotive luminaires, then gives a detailed solution of using the near-filed goniophotometer to acquire luminance, luminous intensity and color distribution. This paper also lists the requirements for near-field goniophotometer in automotive luminaire design, and practical examples.

Key Words: LED automotive luminaires; far-field distribution measurement; near-field distribution measurement; near-filed goniophotometer