We propose a calculation method of computer generated holograms that can reconstruct 3D images with visual effects accompanied by viewpoint movement. Visual effects are added to sampled rays of the object, and ray information is converted to the wavefront of the object. In the experiment, we computed 192K x 128K pixels CGH. The generated fringe pattern is fabricated as a binary amplitude mask by laser-lithography system. 3D image with visual effects were successfully reconstructed by illuminating the fabricated CGH.
New techniques for computer-generated hologram (CGH), for example full-color reconstruction, have been developed for the last few years. As a result, CGH are expected as a new digital art much more than before. However, programming skills were required to design and calculate CGHs. To ease this situation, software tools have been developed for non-expert people to calculate full-color CGHs. In this study, a series of application programs for large-scale CGHs, especially for full-color CGHs, are developed to calculate object fields, generate fringes pattern, and simulate its reconstruction without programming.
Full-color CGHs using RGB color filters is not suitable for mass production, because it is necessary to align the color filters with the fringe pattern with high precision. Furthermore, the problem of blur occurs in the reconstructed image because of the wideband properties of the color filters. To reduce the problems and create full-color CGHs capable of reconstruction by white light, an original full-color CGH is transferred to photopolymer as the volume hologram using a contact copy technique.
We have been developing fringe printer that can output a holographic fringe image calculated as a computer-generated hologram. The printer demagnifies the fringe pattern displayed on liquid crystal display panel and projects it onto a holographic recording material. Previous fringe printer lens had problems of low diffraction efficiency and distortion of interference fringes due to aberration. In this paper, improvement of diffraction efficiency and interference fringe distortion are performed by changing to a lens with aberration correction.
In previous study, we had developed multi-color volume hologram printer which output 2 color components holograms. This system required manually switching of the laser when output a different color component. Furthermore, the reconstructed image was biased in color because proposed hologram piled up the color component holograms. In this study, we developed a full-color volume hologram printer with three lasers whose wavelength are primary colors and multiple exposure method. A fringe pattern is calculated with respect to each wavelength. Calculated fringe pattern is displayed on LCoS and exposed for each wavelength of laser.
An approximation of the cosine function is one of the solution for reducing the computational load in holographic calculation. Our previous work, which approximates the cosine function by a combination of addition, modulo and absolute operation, is proved to be effective for accelerating holographic calculation; however, its approximation error also degrades a performance of a hologram. In this study, we propose an error compensation method which is based on our previous work, and succeeded in reducing the mean absolute error by about 85% compared to our previous work. Moreover, our work also succeeded in improving an image quality of reconstruction image of computer-generated hologram.
Various computer-generated holograms (CGH) have been studied to reconstruct complex and resolution images. We have evaluated objectively with structural similarity (SSIM) showing the reproducibility of CGH and diffraction efficiency showing brightness, and studied the difference in image quality by calculation method. However, we have not yet compared objective evaluation and subjective evaluation. Therefore, in this study, we compare the objective image quality evaluation of Fourier transform hologram, subjective image quality evaluation, and subjective evaluation of optically reconstructed CGH and validate the objective image quality evaluation method.
In the case of a hologram displaying three dimensions, reconstruction illumination light is necessary to visualize it. In other words, the use of the visible light that transmission and the reconstruction of the hologram are possible is effective. However, the use in infrared rays of an electric wave and the IrDA (Infrared Data Association) of the conventional communication was hard to reconstructed. Therefore we reduced influence of the dispersion using a narrow band pass filter of the half bandwidth and improved the reconstruction image. After having carried out activity, we applied a visible light device to an IrSimple technology and examined possibility of the visible light communication. Thus, we apply IrSimple protocol to a visible light technology and report it in the transmission of the computer composition hologram and the one which reconstructed.
We proposed light-field display composed of holographic optical element and projector. Three-dimensional real image formed by the display can be touched, and the touch can be detected by capturing scattered light. We are studying interactive display and user interface using this principle (holographic 3D touch). In this report, we introduce the principle and experimental results on holographic 3D touch using moving-image projection.