Jing Lei, Wang Yao, Zhao Huifu, Ke Hongliang, Wang Xiaoxun, Gao Qun
Appl Opt. 2017 Jun 10;56(17):4961-4966. doi: 10.1364/AO.56.004961.
In order to meet the requirements of uniform illumination for optical palm/fingerprint instruments and overcome the shortcomings of the poor uniform illumination on the working plane of the optical palm/fingerprint prism, a novel secondary optical lens with a free-form surface, compact structure, and high uniformity is presented in this paper. The design of the secondary optical lens is based on emission properties of the near-infrared light-emitting diode (LED) and basic principles of non-imaging optics, especially considering the impact of the thickness of the prism in the design. Through the numerical solution of Snell's law in geometric optics, we obtain the profile of the free-form surface of the lens. Using the optical software TracePro, we trace and simulate the illumination system. The results show that the uniformity is 89.8% on the working plane of the prism, and the test results show that the actual uniformity reaches 85.7% in the experiment, which provides an effective way for realizing a highly uniform illumination system with high-power near-infrared LED.
为满足光学掌纹/指纹识别仪器均匀照明的要求，克服光学掌纹/指纹棱镜工作面上均匀照明差的缺点，本文提出了一种新型的具有自由曲面、结构紧凑且均匀性高的二次光学透镜。二次光学透镜的设计基于近红外发光二极管（LED）的发射特性和非成像光学的基本原理，在设计中特别考虑了棱镜厚度的影响。通过几何光学中斯涅尔定律的数值求解，得到了透镜自由曲面的轮廓。利用光学软件TracePro对照明系统进行了追迹和模拟。结果表明，棱镜工作面上的均匀性为89.8%，测试结果表明实验中实际均匀性达到85.7%，为实现高功率近红外LED的高均匀照明系统提供了有效途径。
