Hong Chuchuan, Colburn Shane, Majumdar Arka
Appl Opt. 2017 Nov 1;56(31):8822-8827. doi: 10.1364/AO.56.008822.
A near-eye visor is one of the most vital components in a head-mounted display. Currently, freeform optics and waveguides are used to design near-eye visors, but these structures are complex and their field of view is limited when the visor is placed near the eye. In this paper, we propose a flat, freeform near-eye visor that uses a subwavelength patterned metasurface reflector. The visor design imparts a spatial phase profile on a projected display pattern and can be implemented using a micron-scale-thick metasurface. As the resulting metaform visor relies on diffraction, it can preserve a large field of view (77.3° both horizontally and vertically) when placed only 2.5 cm away from the eye. We simulate the metasurface visor to estimate the modulation transfer function, and find that the projected image quality is sufficiently high for human vision. While the design of the metasurface is initially performed via ray optics, using full-wave finite-difference time-domain simulation we validate a scaled version of our visor design.
近眼面罩是头戴式显示器中最重要的组件之一。目前，自由曲面光学器件和波导被用于设计近眼面罩，但这些结构复杂，且当面罩靠近眼睛放置时其视野有限。在本文中，我们提出了一种扁平的、采用亚波长图案化超表面反射器的自由曲面近眼面罩。该面罩设计为投影显示图案赋予了空间相位分布，并且可以使用微米级厚度的超表面来实现。由于所得的超表面面罩依赖于衍射，当放置在距离眼睛仅2.5厘米处时，它可以保持较大的视野（水平和垂直方向均为77.3°）。我们对面罩进行了模拟以估计调制传递函数，发现投影图像质量对于人类视觉而言足够高。虽然超表面的设计最初是通过光线光学进行的，但我们使用全波时域有限差分模拟验证了面罩设计的缩放版本。
