Holographic AR display based on the cylindrical holographic optical element for wide viewing zone
Holographic AR display based on the cylindrical holographic optical element for wide viewing zone
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基于圆柱全息光学元件的宽视域全息AR显示
DOI：
10.1117/12.2543588
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
and T. Yatagai
中科院分区：
文献类型：
--
作者：
Y. Sando;K. Satoh;D. Barada;and T. Yatagai
提出了一种基于柱面全息光学元件的全息增强现实显示器。圆柱形HOE用作波长选择反射屏。三维（3D）物体不是直接在圆柱形HOE上重建的，而是在其后面作为虚拟图像。因此，可以在没有物理接触的情况下将3D重建图像与真实存在的3D对象混合：可以实现增强现实。此外，在我们的方法中，HOE的形状不是平面的，而是圆柱形的。由于其形状，我们的方法的观察区变得比平面全息图的观察区宽得多，其中观察区基本上仅限于平面全息图的前向区域。在我们的方法中，要重建的3D对象的信息被编码到一个传统的平面全息图，如空间光调制器（SLM）。然后，由平面全息图调制的波前进入圆柱形HOE。因为圆柱形HOE以非常宽的发散角反射入射波前，所以观看者可以从非常宽的水平范围观察3D对象。为此，我们的方法利用了圆柱表面上的反射。因此，用于调制波前的全息图的设计必须适当地考虑圆柱形HOE上的反射。在我们的方法中，波前通过圆柱形HOE的传输计算的几何光学的基础上。为了验证我们的方法，我们进行了光学实验，我们的全息AR显示成功地证明。
We propose a holographic augmented reality (AR) display by using a cylindrical holographic optical element (HOE). The cylindrical HOE is used as a wavelength-selective reflective screen. A three-dimensional (3D) object is not reconstructed on the cylindrical HOE directly, but behind it as a virtual image. Thus, it becomes possible to superimpose the 3D reconstructed image with a real-existent 3D object without physical contact: augmented reality can be achieved. Moreover, in our method, the shape of the HOE is not planar but cylindrical. Thanks to its shape, the viewing zone of our method becomes much wider than that of planar hologram, where the viewing zone is fundamentally limited to only the forward region of the planar hologram. In our method, information of the 3D object to be reconstructed is coded into a conventional planar hologram such as a spatial light modulator (SLM). Then, the wavefront modulated by the planar hologram enters the cylindrical HOE. Because the cylindrical HOE reflects the incident wavefront with a very wide diverging angle, viewers can observe the 3D object from a very wide horizontal range. For this purpose, our method utilizes the reflection on the cylindrical surface. Thus, holograms for modulating the wavefronts have to be designed considering the reflection on the cylindrical HOE properly. In our method, wavefront propagation via the cylindrical HOE is calculated based on the geometric optics. To verify our method, we performed optical experiments, and our holographic AR display was successfully demonstrated.