本研究主要是提出一種自由曲面設計方法,設計出汽車LED近光燈反射系統。其中包含一個自由曲面形式的反射鏡以及LED光源。反射鏡的輪廓是使用本研究所提出的自由曲面建構方法,此方法可以依照使用者的不同需求,使光線反射出使用者所指定的光型分布圖。本研究主要利用歪斜光線追蹤法與建立大量的點資料來對自由曲面進行建模,最後所設計之汽車LED近光燈反射系統使用光學分析軟體ZEMAX進行模擬,其結果顯示此反射系統所投射出的光型分布圖以及指定照度檢測點均符合歐規非對稱近光燈ECE R112所要求標準。因此,本研究所提出的自由曲面建構方法為光學系統的設計和分析提供了一個實用的工具。
A free-form surface design method is proposed for a vehicle LED low-beam headlamp system comprising a free-form reflector and a LED light source. The profile of the reflector is designed using a free-form (FF) surface construction method such that each incident ray is directed in such a way as to form a user-specified light pattern on the measuring plane. The light ray paths within the headlamp system are analyzed using an exact analytical model and a skew-ray tracing approach. The validity of the proposed FF design method is demonstrated by means of ZEMAX simulations. It is shown that the light pattern formed on the measuring plane is in good agreement with the United Nations Economic Commission for Europe vehicle regulations R112 regulation. The FF method is mathematically straightforward and easily implemented in computer code. As such, it provides a useful tool for the design and analysis stages of optical systems design.