title: Reduction of the recorded speckle noise in holographic 3D printer.
abstract: A holographic 3D printer produces a high-quality 3D image reproduced by a full-color, full-parallax holographic stereogram with high-density light-ray recording. In order to produce a high-resolution holographic stereogram, we have to solve the problem of speckle noise in this system. For equalizing an intensity distribution inside the elementary hologram, the object beam is modulated by a diffuser. However the diffuser typically generates speckles, which is recorded in the holographic stereogram. It is localized behind the reconstructed image as a granularity noise. First we show the problems of some conventional ways for suppressing the granularity noise using a band-limited diffuser, and then we analyze an approach using a moving diffuser for the reduction of this noise. In the result, it is found that recording with a moving diffuser is effective for reducing the granularity noise at infinity of reconstructed image, although an alternative noise occurs. Moreover we propose a new method introducing multiple exposures to suppress the noise effectively.
authors: Department of Information Processing, Tokyo Institute of Technology, Midori-ku, Yokohama, Kanagawa, Japan. utsugi.t.aa@m.titech.ac.jp
authors: Takeru
authors: T
authors: Utsugi
authors: Masahiro
authors: M
authors: Yamaguchi