Kenji Taima

New approach to the interactive holographic display system

This paper presents a new type of the interactive holography display system which features both dynamic and precisely detailed imaging. The main discussion is on synthesis of electronic holograms and optical holograms. Electronic holograms have benefits of dynamic imaging of computer generated 3D objects in essence. On the other hand, conventional optical holograms are known to be suitable for detailed and precise imaging. Considering that many images typically contain objects which dynamically move around on the still background, synthesis of electronic holograms and optical holograms has high potential that the currently limited electronic holograms are applied to a wide range of applications. The second discussion of this paper is about the possibility of producing computed holograms in real time. Computation time of generating holographic fringe patterns with a parallel computer CYBERFLOW is considerably reduced by using techniques such as parallel computation with and within 64 processing elements, vectorized computation, scalar computation simultaneously in parallel with vector computation, and simultaneous computation with data transfer to the output display device. The obtained result is 84.7 times as fast as a conventional computer and promises the possibility of the real time computer generated hologram.

Edge-illuminated color holograms

The method for reconstructing a hologram through an edge of the glass cover plate is discussed from the standpoint of the imaging characteristics. Holograms fabricated by this method do not need large free space for illumination and can be reconstructed compactly. The image blur of the hologram reconstructed with white light is analyzed. Experiments of recording color holograms by this method are also reported.

Three-dimensional shape measurement using images reconstructed by the computer from a hologram

Laser holographic interferometry has been developed to provide a direct optical transonic flow diagnostic tool. It is often convenient, due to the needs of passage instrumentation and blade fixtures, to restrict optical access to one side of the test facility. To overcome this limitation a reflective holographic system has been devised which uses one of the internal tunnel walls as a mirror surface. However, due to the movement of the facility, spurious rigid body vibration information is added to the transonic flow data. A numerical method has been developed by Warwick University and demonstrated on the Laval nozzle flow facility at EPFL which uses a digital fast Fourier transform algorithm to remove the superimposed background information. A further method known as phase unwrapping is used to extract quantitative numerical data from the interferometrically formed images automatically. A complication to the experiment was created by the non-linear deflection of glass window between the two holographic exposures. The deflection was determined experimentally to be of a parabolic nature and has been successfully removed. This was achieved by post processing the unwrapped fringe data.

Compact display system for holograms

A compact display system using reflection type rainbow hologram is proposed. This hologram is reconstructed by using a large illumination angle in air, not edge illumination. A good reconstructed image is obtained by adoption of a louver film.

Application of multiplex holograms

We propose a new fabrication method of multiplex holograms and present an example made by this method. We studied the possibility to display the perspectives on a liquid crystal panel for a computer display and the convenient way to convert the perspectives to film. The way of conversion is more useful than using liquid crystal panel at the present. We also propose an idea of an attractive object to demonstrate by multiplex hologram. The object is designed with a typical CG technique morphing. Faces of animals are metamorphosed and exposed in a hologram as a sequential image. And then it is divided into two loops and each hologram turns at a different speed. We can look at many different synthesized images from combinations of plural multiplex holograms.