Browsing by Subject "Fresnel hologram"

Now showing 1 - 3 of 3

Open Access
Method to enlarge the hologram viewing window using a mirror module
(2009) Kang H.; Ohmura, N.; Yamaguchi, T.; Yoshikawa H.; Kim, S.-C.; Kim, E.-S.
A liquid crystal panel for a video projector is often used for holographic television. However, its pixel size and pixel number are not enough for practical holographic 3-D display. Therefore, a multipanel configuration is generally used to increase the viewing window and displayed image size, and many spatial light modulators should be used in them. We propose a novel method to increase the viewing window of a holographic display system. The proposed method, which is implemented by using a mirror module and 4-f lens set, is to reconfigure the beam shape reflected by a spatial light modulator. The equipment is applied to a holographic display system, which has only a single spatial light modulator; a hologram could be displayed in a wider viewing window by the equipment than that of the conventional method. By the proposed method, the resolution of the reconfigured spatial light modulator has double resolution in the horizontal direction. Inversely, the vertical resolution is decreased. Even if the vertical resolution is decreased, a viewer could get 3-D effect because humans get more 3-D information in the horizontal direction. We have experimented using a liquid crystal on silicon (LcOS), whose resolution is 4096×2160pixels. The reconfigured resolution by the mirror module is 8192×1080pixels. From the experiments, the horizontal viewing window is almost two times wider than that without the mirror module. As a result, the hologram can be observed binocularly. © 2009 Society of Photo-Optical Instrumentation Engineers.
Open Access
Quality comparison and acceleration for digital hologram generation method based on segmentation
(IEEE, 2009) Kang, Hoonjong; Yaraş, Fahri; Onural, Levent
A holographic fringe pattern generation methods is based on Fraunhofer diffraction and subsequent segmentation and approximation of the fringe pattern. Several modifications of the original algorithm are already proposed to improve the quality of reconstructions. We compare the quality of to the reconstructed images from different versions of this algorithm by taking the reconstructions from the Fresnel hologram as a reference. Since, there is not any generally accepted objective quality assessment method for such reconstructions, we used some experimental methods such as intensity spread over the reconstructed images, total noise power, and peak-signal-to-noise for comparison. Then we chose the best performing algorithm in terms of ireconstruction quality, and developed a GPU-based implementation to accelerate the computation speed. The quality of the resultant reconstructions is comparable to reconstructions from Fresnel holograms; much higher speed is achieved due to multi-GPU implemetation.
Open Access
Two-photon excitation of quantum dots in 3D via stacked fresnel hologram algorithm
(OSA, 2017) Kesim, Denizhan Koray; Makey, Ghaith; Yavuz, Özgün; Tokel, Onur; İlday, Fatih Ömer
Quantum dots are engineered to have nanometers dimensions. The ability to specify the diameter and the material of the quantum dots allow us tune the absorption and emission properties. This results in extensive capabilities for imaging and display applications. Further, with two photon absorption and high peak power laser they can be excited at any point in 3D locally.