The holographic stereogram approach is used to calculate computer generated holograms fast. If we use computer graphics (CG) for 2-D picture array of the stereogram, fast computation of CG also becomes important. In this paper, we discussed improvements of computational speed to generate the CG array. In our previous method, each CG was calculated independently. Since the viewing point of the CG array changes horizontal direction only, many part of the CG calculation can be done only once for the CG array. In addition, decreasing intermediate file input/output also reduces total computation time.
We have been studying the computer generated hologram (CGH) for the electro-holographic display. In our research, we have investigated about the fast computing algorithms and the fast computing architectures. In this report, we describe the CGH using parallax image, result of simulation and fast calculation system we are now constructing.
Personal identification is an important technique in security systems. Recognition using facial characteristics is known to be a promising candidate for non-contact methods. Yet no effective face recognition system has been established in all electronic environment. This is mainly due to the complex facial features which are difficult to express with the limited parameters extracted from facial characteristics. Furthermore digital pattem matching required data intensitive calculations, which limit shortening of processing time. In this paper, we propose an opt-electronic hybrid face recognition system based on a real time JTC using 2 types liquid crystal spatial light modulator (LCSLMs) and binary array elements. Experimental investigations on recognition ability of this system are reported. Finally, the effect of spectral analysis of primary hologram on Frequency domain for facial recognition is confirmed.
It is not practical to apply 2D image compression directly to the hologram because the character of the holographic fringe data is quite different from that of normal 2D images. We have found that the spatial frequency spectrum of the segmented hologram becomes similar to the perspective images of the object. It, however, contains not only amplitude but also phase information of the object. Therefore, we extract phase information and compress amplitude and phase independently. We have also discussed combining other compression technique to obtain higher total compression rates. Experimental results show that the total compression rate of 1/192 is obtained with small affect on image quality.
Simulated annealing (SA) is applied to synthesize computer-generated holograms for three dimensional images reconstruction. The advantage of SA is the fact that global optimum hologram is obtained. Image quality depends on cost functions in SA. Combination of two cost functions gives superior reconstructed images compared to one cost function independently.
A liquid-crystal television (LCTV) provides coupled amplitude and phase modulation. We optimize the coupled mode modulation of the LCTV by varying the polarizer and analyzer angles to reduce the amplitude modulation. Kinoforms are designed with a least-square method to improve the performance of noise and zero-order spots of reconstructed images with the optimal operation of the LCTV. The reconstructed zero-order sport on the kinoform displayed by the LCTV can be auppressed by optimizing the polarizer and analyzer angles.
Although generating electronic hologram requires huge amount of computation, we succeeded in real-time generation of moving images by a parallel computer with 64 processor elements. The quality of the image, however, was poor because the computer performance limited the number of point sources. In this paper, we aim at high speed generation of higher quality images by a parallel computer with 128 processor elements. We succeeded in generating a hologram more than twice as fast as 64 processor elements by dividing the hologram among the processor elements so that each of them can be loaded equally.
An investigation has been made on computer-generated holograms for 3-D objects composed of plane surfaces. Brightness of the plane surface uniformly filled with point sources is analyzed by a model based on photometry. Algorithm which effectively utilizes geometric relations between the plane surface and a hologram is suggested for a fast calculation of object waves.
We constructed an electro-holography system using parallel Aligned Nematic Liquid Crystal Spatial Light Modulator (PAL-SLM) and we considered to improve the image quality by controlling the polarization angle of reconstructing light. As the result we could obtain the clear image by decreasing the zero order light intensity at special polarization angle of reconstructing light. From now on we consider to obtain the high contrast reconstructing image by this method.
The LCTV-SLM (liquid crystal TV spatial light modulator) is a suitable device for electro-holography because it is very easy to modulate light waves by electric signals. But unfortunately, the resolution and a number of pixels of the LCTV-SLM are quite low for holographic devices now. So it is very important to remove 0 th. order light on reconstruction because of its quite low career spatial frequency of the SLM. To solve this problem we studied polarization filtering technique instead of the spatial filtering and the relatively good result is obtained.
In binocular stereoscopic display using binocular disparity (parallax), there is distance difference between the screen position and image position constructed by stereoscopic disparity. It is considered that the ocular fatigue is due to the unbalance between visual accommodation and eye movement vergence. In this paper, I discussed characteristics of accommodation and vergence while viewing binocular stereoscopic display.
With a binocular stereoscopic 3D display system, one of the major problems in stereoscopic 3D display is the mismatch of distance between the accommodation and convergence of human eye. Therefore, from a dynamic characteristic of accommodation response, we considered whether a binocular stereoscopic 3D display system is sultable or not. Experiments were conducted to understand how the stereoscopic 3D images influence human visual functions. Concretely, we compared an accommodation distance and a convergence distance, accommodation of a genuine article and a stereoscopic 3D display.
3D display which uses anamorphic optics can horizontally increase the number of parallaxes and can give the motion parallax. As a result, more natural 3D image can be displayed. We constructed 3D display (Model 2) this time. In this model, We use the LCDs as the display device and change the composition of the optics system. As a result, a stripe shade part which was the problem of Model 1 was able to be reduced. Moreover, we compare quality of images which obtain changing the number of paraliaxes. It was confirmed to obtain high quality 3D image by increasing the number of parallaxes.
We are constructing a 3-D TV using liquid crystal device (LCD) for reconstructing holographic image. The viewing angle is so small that long distance is necessary for viewing the reconstructed image by both eyes. It is very difficult to observe the image because hologram image is very small. We used eye-lens to shortening the viewing distance and to observe the reconstructed real image easy. We consider about the characteristics of the focusing of reconstructed image.
We have investigated exposure parameters of new holographic recording material (BB-PAN) having the sensitivity for red, green, blue light. As an example of this material, Lippmann type reflection hologram is demonstrated.
This paper would emphasize an aspect of "How to use holography for physics education"and would explain the fundmental principle as well as verious educational and scientific applications. Students in our class are presented with a great deal of physical demonstrations, sudiovisual aides and the exhibition of many kinds of holograms. A display of existing educational, artistic and technical holograms is physically followed by a detalled analysis. These holograms could be made using a holography-camera by students without spacial technique. Because we could spare time setting up the optical compoments and elements. This method of physics education making holograms is expected by many students. They could make fresnel holograms (master hologram) at the first time. These holograms could are transfered to be white light reconstruction holograms by them within 3 hours. Lippmman holorams and rainbow holograms could be made.
A new method for the display of high-quality color image is presented to improve the color gamut. Extended color gamut are reproduced by more than three primaries generated by a diffractive optical element and a liquid crystal panel. In this paper, the optical system for the multi-primary is introduced, and the conversion formula of color image data is described. By the experiment, extended color gamut is obtained as compared with conventional CRT system.
Holographic Optical Elements with wavelength-separating and focusing capabilities have been developed. By producing two peak holograms with one peak in the red region and the other in the blue region, the light efficiencies of the two peak holograms have been improved compared with those of single peak holograms.