Electro-holography equipped with a spatial light modulator (SLM) is considered to be an important basic technique for 3D-TV. However, the resolving power of ordinary SLM seems to be very low, and so it looks very difficult to satisfy the space-bandwidth product (SBP) condition. It is unfavorable since the values of the size and the viewing angle of the reproduced images are known to be restricted. We tried to manage this problem by introducing several processes using a spatial screen of a mist flow or a micro-bubble, and discharged air plasma. In these processes, since we have jetted out the scatterer into the space directly, fluctuation reducing process of the screen has come to be an important problem. In this paper, we shall report that, to improve the stability of the mist screen, a spatial screen employed a bladeless fan (without blades) is introduced, and a challenge is made for holographic projected images to be presented in an extended display area of the screen. As this result, we confirmed that an effective display area is exactly enlarged, and a performance of highly bright projected images is carried out by this new system.
Spatial projection of holographic reconstructed images by blue-violet laser light is stated. Studied results are reported. Firstly, construction of mist screen is introduced, and the conditions under which optical characteristics of the screen will be improved are reported. Evaluation of improved situation is carried out by objective and subjective evaluating technics. Reconstructed images obtained by projecting blue-violet laser light are shown, and a relation between the usage of two kinds of fans and the quality of the projected images (brightness and stability) is studied. It is carried out by combining optical characteristics (objective evaluation), subjective evaluation and automatic decision making based on image analyzing process. By this, a certain relation is seen to exist between the result derived from each of the evaluating processes and the projected image judged as "good". Using this result, it is found that a clear projection of the images by blue-violet laser light is really possible.
In order to perform a nice space projection in the reconstructing process by the hologram containing the information of the laser lights with red, green and blue three primary colors, it may be strongly required that we must study more to improve the quality of the reconstructed images using each of the holograms generated by each of the three color lasers, and make efforts to establish a stable, smooth representing process of the holographic images of the moving pictures. Further, to extend the region of the reproducible colors, as for the blue color laser lights, it seems to be effective to employ the blue-violet laser light of shorter wave length, which corresponds to the minimum wave length of the visible ray. However, this in turn implies some difficulty in the image reproduction using diffraction. Taking care that the reproducibility of the images of the moving picture generally depends on the refresh-rate of the elements of the display, we may see that it important to study the relation between the numbers of frame required for the formation of the reproduced picture and of the hologram elements required for one sheet of still picture. In this paper, we are going to make reports on the results concerning the required number of the points of the object for which we can reproduce it as the point object by the use of the blue-violet laser light without applying time-shared multiplex reproducing technique.
In order to develop a technical process to display holographic reconstructed images in colors, it seems to be very important to extend the holographic displayable region of colors, and so the study of displaying process of the reconstructed images in colors with the use of blue-violet laser light (wavelength: 405 nm)seems to be crucial. We have studied how to improve the characteristics of the displayable region of the reconstructed images using blue-violet laser light when time-sharing multiplex reconstructing technique is employed. In this report, we are going to show some improved displaying characteristics of the object with the curved shape, and to propose some useful basic suggestions for a colorful display of reconstructed holographic images when blue-violet laser light is applied.
In order to display holographic reconstructed images in colors, we must sufficiently study the characteristics of the images reconstructed by multiplex reconstructing process and spatially multiplex holographic projecting process using blue-violet laser light. But in general, in the reconstruction of the images, if we use the laser lights of the short wave length, their reconstruction seems to be more difficult. Moreover, as for the reconstruction adopted blue-violet color laser light, it seems to have been not reported so many results. For this, we study first the relation between the number of the points of the object and the reconstructed image quality by applying multiplex reconstructing process adopted blue-violet laser light. Next, we study a basic coloring process by applying spatially multiplex holographic projecting technique using blue violet laser light. In this paper, we shall report how effectively the holographic image reconstruction adopted blue-violet laser light (wavelength: 405nm) plays its role to present the image of high quality through time-sharing multiplex reconstruction and to enlarge color region of the reconstructed image through time-sharing spatially multiplex holographic projection.. In addition, we studied a process which produces, by time-sharing spatially multiplex projection on the screen, the two colored images by time-sharing multiplex reconstructing technique using two color lasers: blue-violet, red (or green). As this result, we have confirmed that single color multiplex reconstructing process, which recovers the divided parts of the objects formed with multiple points, is also applicable to time-sharing spatially multiplex reproducing process using two colors. This seems to suggest some possibility of the color region enlargement of the recovered holographic images.
As an effective reconstructing technique to observe full-parallax holographic images in the wide viewing area, we have studied a projecting process of 3-D holographic images with the use of the spatial screen. Last year, as one technique to perform a suitable projection of the images, we have reported a projecting process of holographic 3-D images onto the underwater micro-bubble screen. Applying this technique, the stability of the images displayed in the screen seems to have been highly improved, however, as for the flickering of the images, much more improvement seems to be not so easy. Moreover, it requires a lot of water in the water tank, so that a complicated and a more weighty system has been needed. For this reason, we constructed a new spatial screen system employed the fog, in which a complicated structure and a lot of water was not required. In this report, we have discussed its effects to the reconstructed images through the holograms. In addition, in this study, we have seen that the system construction seems to be simple and not so weighty, and effective for suppressing the flickering of the images with higher resolution.
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