Zou Junyu, Zhan Tao, Hsiang En-Lin, Du Xinpeng, Yu Xiaoming, Li Kun, Wu Shin-Tson
Opt Express. 2021 Jun 21;29(13):20673-20686. doi: 10.1364/OE.430920.
We demonstrate an approach to double the optical efficiency of virtual reality (VR) systems based on a directional backlight and a diffractive deflection film (DDF). The directional backlight consists of a commercial collimated light-emitting diode (LED) array and a two-layer privacy film, while the DDF is a three-domain Pancharatnam-Berry (PB) phase lens. Such a PB phase lens was fabricated by the zone exposure and spin-coating method. The focal length of each domain is designed according to the imaging optics of the VR system. Our approach works well in both Fresnel and "pancake" VR systems. We also build the corresponding models in LightTools, and the simulation results are in good agreement with experiment. In experiment, we achieved a 2.25x optical efficiency enhancement for both systems, which agrees with the simulation results (2.48x for Fresnel and 2.44x for "pancake" systems) well. Potential application for high efficiency VR displays is foreseeable.
我们展示了一种基于定向背光源和衍射偏转膜（DDF）将虚拟现实（VR）系统的光学效率提高一倍的方法。定向背光源由商用准直发光二极管（LED）阵列和两层隐私膜组成，而DDF是一种三畴潘查拉特纳姆-贝里（PB）相位透镜。这种PB相位透镜是通过区域曝光和旋涂法制造的。每个畴的焦距是根据VR系统的成像光学原理设计的。我们的方法在菲涅耳和“煎饼”式VR系统中都能很好地工作。我们还在LightTools中建立了相应的模型，模拟结果与实验结果吻合良好。在实验中，我们在两个系统中都实现了2.25倍的光学效率提升，这与模拟结果（菲涅耳系统为2.48倍，“煎饼”系统为2.44倍）非常吻合。高效VR显示器的潜在应用是可预见的。
