Fast Extended Depth of Focus Meta-Optics for Varifocal Functionality
Fast Extended Depth of Focus Meta-Optics for Varifocal Functionality
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DOI：
10.1364/prj.434681
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发表时间：
2021-06
影响因子：
7.6
通讯作者：
James E. M. Whitehead;A. Zhan;S. Colburn;Luocheng Huang;A. Majumdar
中科院分区：
文献类型：
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作者：
James E. M. Whitehead;A. Zhan;S. Colburn;Luocheng Huang;A. Majumdar
与主动聚焦解决方案相比，扩展的焦深(EDOF)光学系统可以实现更低的复杂性光学成像系统。然而，利用现有的EDOF光学器件，很难同时实现高分辨率和高收集效率。元光学的亚波长间距使得工程中可以设计非常陡峭的相位梯度，因此元光学可以实现大的物理孔径和高的数值孔径。在这里，我们展示了一种工作在可见光波长下的快速(f/1.75)EDOF准光学元件，孔径为2 mm，焦距范围从3.5 mm到14.5 mm(286到69屈光度)，相对于标准透镜，焦深延长了250倍。通过在有限共轭范围内成像，显示出与深度无关的性能，最小空间分辨率为~9.84μm(50.8周期/mm)。我们还演示了直接集成EDOF元光学相机模块的操作，以评估多个对象距离的成像，否则这一功能将需要变焦镜头。
Extended depth of focus (EDOF) optics can enable lower complexity optical imaging systems when compared to active focusing solutions. With existing EDOF optics, however, it is difficult to achieve high resolution and high collection efficiency simultaneously. The subwavelength pitch of meta-optics enables engineering very steep phase gradients, and thus meta-optics can achieve both a large physical aperture and high numerical aperture. Here, we demonstrate a fast (f/1.75) EDOF meta-optic operating at visible wavelengths, with an aperture of 2 mm and focal range from 3.5 mm to 14.5 mm (286 diopters to 69 diopters), which is a 250 × elongation of the depth of focus relative to a standard lens. Depth-independent performance is shown by imaging at a range of finite conjugates, with a minimum spatial resolution of ~9.84μm (50.8 cycles/mm). We also demonstrate operation of a directly integrated EDOF meta-optic camera module to evaluate imaging at multiple object distances, a functionality which would otherwise require a varifocal lens.