Yamaguchi Takeshi, Fujii Tomohiko, Yoshikawa Hiroshi
Department of Electronics and Computer Science, College of Science and Technology, Nihon University, 7-24-1 Narashinodai, Funabashi-shi, Chiba 274-8501, Japan.
Appl Opt. 2009 Dec 1;48(34):H16-22. doi: 10.1364/AO.48.000H16.
We have been investigating disk holograms made from a computer-generated hologram (CGH). Since a general flat format hologram has a limited viewable area, we usually cannot see the other side of the reconstructed object. Therefore, we propose a computer-generated cylindrical hologram (CGCH) to obtain a hologram with a 360 deg viewable area. The CGCH has a special shape that is difficult to construct and calculation of such a hologram takes too much time. In contrast, a disk-type hologram is well known as a 360 deg viewable hologram. Since a regular disk hologram is a flat reflective type, the reconstruction setup is easy. However, there are just a few reports about creating a disk hologram by use of a CGH. Because the output device lacks spatial resolution, the hologram cannot provide a large diffraction angle. In addition, the viewing zone depends on the hologram size; the maximum size of the fringe pattern is decided on the basis of the special frequency of the output device. The calculation amount of the proposed hologram is approximately a quarter of that of a CGCH. In a previous study, a disk hologram made from a CGH was achieved. However, since the relation between the vertical viewing zone and reconstructed image size is a trade-off, the size of the reconstructed image and view zone is not enough for practical use. To improve both parameters, we modified a fringe printer to issue a high-resolution fringe pattern for a disk hologram. In addition, we propose a new calculation method for fast calculation.
我们一直在研究由计算机生成全息图（CGH）制成的圆盘全息图。由于一般的平面格式全息图的可视区域有限，我们通常无法看到重建物体的另一面。因此，我们提出了一种计算机生成的柱面全息图（CGCH），以获得具有360度可视区域的全息图。CGCH具有特殊的形状，难以构建，并且计算这样的全息图需要花费太多时间。相比之下，圆盘型全息图是众所周知的360度可视全息图。由于常规的圆盘全息图是平面反射型的，其重建设置很简单。然而，关于使用CGH创建圆盘全息图的报道却很少。由于输出设备缺乏空间分辨率，全息图无法提供大的衍射角。此外，观看区域取决于全息图的大小；条纹图案的最大尺寸是根据输出设备的特定频率确定的。所提出的全息图的计算量大约是CGCH的四分之一。在先前的一项研究中，实现了由CGH制成的圆盘全息图。然而，由于垂直观看区域与重建图像大小之间的关系是一种权衡，重建图像的大小和观看区域对于实际应用来说还不够。为了改善这两个参数，我们对条纹打印机进行了改进，以生成用于圆盘全息图的高分辨率条纹图案。此外，我们提出了一种新的计算方法以进行快速计算。
