Huang Kuo-Yin, Chang Ke-Peng, Chang Yung-Peng, Liu Chun-Nien, Cheng Wood-Hi
Opt Express. 2023 Jul 17;31(15):25307-25317. doi: 10.1364/OE.495206.
We present, what we believe to be, a novel microlens array (MLA) scheme for laser light shaping in laser scanning smart headlight. The laser spot has a Gaussian distribution that may reach a high peak power density in the central part, which is called hot spot. When the laser beam is applied to a phosphor plate for luminous conversion, the hot spot of Gaussian beam causes thermal quench and decreases luminous efficacy. To avoid this effect, an MLA is used, so as to achieve a uniform energy distribution. In this study, we propose a laser scanning smart headlight fabricated by a new MLA structure, with an arrangement providing both light uniformity and shaping. The novel MLA is designed by two-dimensional micro-concave lens array yielding a flat-top beam. The flexible fabrication process employs laser drilling to shape the micro-hole array on the glass substrate surface and then etch it to form MLA without requiring any mask lithography process. The full-width half maximum (FWHM) of light output distribution can be adjusted by the glass etching parameters, and the light distribution could be controlled by the arranged layout of the array. Thus, beams with FWHM divergence ranging from 5° to 34° has been fabricated and characterized. The typical pixel shape is a rectangle with two different FWHMs in two orthogonal directions, and the fabrication method achieves this goal as well. This novel design and unique maskless process of the MLAs is a promising tool for development the next generation laser scanning smart headlight.
我们提出了一种我们认为新颖的微透镜阵列（MLA）方案，用于激光扫描智能头灯中的激光光束整形。激光光斑具有高斯分布，在中心部分可能会达到较高的峰值功率密度，这被称为热点。当激光束照射到荧光粉板上进行发光转换时，高斯光束的热点会导致热猝灭并降低发光效率。为避免这种影响，使用了微透镜阵列，以实现能量分布均匀。在本研究中，我们提出了一种由新型微透镜阵列结构制造的激光扫描智能头灯，其排列方式既能提供光均匀性又能实现光束整形。这种新型微透镜阵列由二维微凹透镜阵列设计而成，可产生平顶光束。灵活的制造工艺采用激光钻孔在玻璃基板表面形成微孔阵列，然后进行蚀刻以形成微透镜阵列，无需任何掩膜光刻工艺。光输出分布的半高全宽（FWHM）可通过玻璃蚀刻参数进行调整，光分布可通过阵列的排列布局进行控制。因此，已经制造并表征了半高全宽发散范围从5°到34°的光束。典型的像素形状是在两个正交方向上具有两种不同半高全宽的矩形，并且制造方法也实现了这一目标。这种微透镜阵列的新颖设计和独特的无掩膜工艺是开发下一代激光扫描智能头灯的一种很有前景的工具。
