| dc.description.abstract | Disk-type multiplex holography was originally proposed by Prof. Cheng, Prof. Su, and Dr. Chang in 1999. However, the finished multiplex holograms are composed of a series of long-thin individual holograms which consequently causes the reconstructed images overlaid with a fence structure. More recently, the image-plane multiplex holograms (IPDTMHs) are developed to be capable of displaying 3D images free from the “picket-fence effect”. The IPDTMH can generate a virtual image behind the hologram. In fact, real images can be generated from the IPDTMHs, which will be proposed in this dissertation. We have further developed a 360-degree viewable IPDTMH in 2004. A single-beam copying system for this kind of hologram will also be introduced. Furthermore, the reflection IPDTMHs for 360-degree viewing are discussed in the last part of this dissertation.
In the first part of this dissertation, we introduce how to generate 3D real images from an image-plane disk-type multiplex hologram. In the formation of a multiplex hologram, a 2D image from original 3D object is directly imaged on to the recording film plane based on the imaging properties of lenses. The theory of this type of hologram is built. This kind of hologram is suitable for white-light line-source reconstruction and the reconstructed 3D image is free from the “picket-fence effect” as occurred in the traditional multiplex hologram. The characteristics of the image are numerically simulated. Since this type of hologram can generate real images as well as virtual images, we also discuss how to generate both images simultaneously with one white-light line-source illumination.
Photo-resist materials are ordinarily used in production of master plates for embossed holograms but we know that the exposure time needed for grating formation in photo resist is much longer than that needed for a silver halide film which of course makes it impractical for multiplex hologram fabrication. It seems that single exposure would be more efficient for mass production. Then, in the second part of this dissertation, a two-step holographic process for the fabrication of an image-plane disk-type multiplex hologram is described. We discuss how to produce a master hologram (H1) and present a simple optical system for single-beam copying process (H2). The diffraction efficiency of the transfer hologram (H2) is measured as a function of exposure. However, it is found to be influenced by the polarization of the light beams of the copying system, resulting in different diffracted beam diffraction efficiencies from two areas (under different interference conditions) of the transfer. The factors which cause the phenomenon of diffraction efficiency difference are demonstrated and the corresponding experimental results are discussed.
A method for making the reflection image-plane disk-type multiplex holograms is also introduced in the last part of the dissertation. A two-step holographic process, including the fabrication of a master hologram (H1) and the production of a transfer hologram (H2), for the fabrication of 360-degree walk around viewable reflection image-plane disk-type multiplex holograms is proposed. In order to increase both the vertical and the longitudinal viewing window, a diffuser and a fan-shaped slit are utilized in the optical system of the object wave in the first-step recording (H1). The finished hologram (H2) can generate single-colored clear image under white-light line-source illumination. An alternative lensless copying system for fabrication of the reflection multiplex hologram, which allows one-shot recording of bigger images, is also described. Both experimental and computer-simulated results for the characteristics of the images from this kind of hologram are presented.
The IPDTMH is suitable for mass production using the well-developed CD technology and it would be an appropriate time to utilize this kind of hologram to display scientific data, tomographic data, and images of people or scenery. The theoretical and experimental results in this dissertation should be helpful in the design of a single-beam holographic transferring system for mass production of IPDTMHs. On the other hand, the image reconstructed with a reflection hologram is quite single-colored because of the property of high wavelength selectivity. Using this property one can design the viewing slits at a fixed location in the reconstruction process for various wavelengths (RGB) and then makes full-color holograms with one laser source by pre-soaking the unexposed film in triethanolamine (TEA) liquid of suitable concentrations in the near future. | en_US |