• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.157-159
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• 2019

Hologram technology has been actively developed in terms of generation, transmission, and reproduction of 3D objects, but it is currently in a state of rest because of various limitations. Beyond VR and AR, the pseudo-hologram market is growing at an intermediate stage to meet the needs of new technologies. The key to the technology of hologram is to generate vast 3 dimensional data in the form of a point cloud, transmit the vast amount of data through the communication network in real time, and reproduce it like the original at the destination. In this paper, we propose a method to transmit massive 3 - D data in real - time and transmit the minutiae points of 3 - dimensional object information to reproduce the object as similar to original.

• Journal of Broadcast Engineering
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• v.25 no.4
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• pp.587-597
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• 2020

In this paper, we analyze the normalization that occurs when processing digital hologram and propose an optimized quantization method. In JPEG Pleno, which standardizes the compression of holograms, full complex holograms are defined as complex numbers with 32-bit or 64-bit precision, and the range of values varies greatly depending on the method of hologram generation and object type. Such data with high precision and wide dynamic range are converted to fixed-point or integer numbers with lower precision for signal processing and compression. In addition, in order to reconstruct the hologram to the SLM (spatial light modulator), it is approximated with a precision of a value that can be expressed by the pixels of the SLM. This process can be refereed as a normalization process using quantization. In this paper, we introduce a method for normalizing high precision and wide range hologram using quantization technique and propose an optimized method.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2001.11a
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• pp.119-122
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• 2001

We derived the resolution of the modified triangular interferometer and described the analysis about distance measurement using the one. Also, to demonstrate the feasibility of distance measurement using the modified triangular interferometer, the incoherent hologram of a two-point source with depth and its numerical reconstruction were presented.

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.102-103
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• 2004

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2000.11a
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• pp.144-148
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• 2000

We presented a modified triangular interferometer as an incoherent holography, which can eliminate bias and conjugate image problems of the conventional one. Also, to demonstrate the feasibility of incoherent holography, the formation of an incoherent hologram using a mercury lamp and its optical reconstruction were presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1018-1021
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• 2007

This paper explores the use of BEM based NAH to reconstruct the surface vibration of a plate in a rectangular finite cavity, in which the distances between sensors and the nearest points on the source surface are not equal. In such circumstances, different degree of information on propagating and non-propagating wave components will be detected by sensors at different positions, as well as the influence of measurement noise will vary significantly from the nearest points of measurement to the farthest ones. On the other hand, the condition number of the vibro-acoustic transfer function matrix relating normal surface velocities and field pressures will becomes high, numerically indicating an increase of linear dependency between rows of transfer function matrix. The combination of poor measurement and high condition number will result inaccurate reconstruction. Therefore, one approach to be investigated in this work is to select the measurement positions in such ways that reduce measurement redundancy, as it indicated by the condition number. The improvement is found to be significant in the numerical simulations utilizing two different criterions, spanning from over-determined to under-determined cases, and in the validation experiment.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.191-198
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• 1998

A method is described to produce off-axis hologram lenses without astigmatism for semiconductor lasers. We fabricated a holographic collimating lens by using dichromated gelatin film with high diffraction efficiency and without astigmatism which makes a collimated off-axis beam of semiconductor laser. We have designed the holographic collimating lens by applying the classical ray-tracing method to holographic diffraction. The elimination of astigmatism is obtained by choosing appropriate angles of recording and reconstruction beams. The hologram is recorded by use of Ar^{+}$ laser (488nm wavelength) and reconstructed by semiconductor laser(670nm wavelength). The physical parameters of recording and reconstruction angles, wavelength, and astigmatism are analytically calculated and experimentally confirmed.

• Journal of Broadcast Engineering
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• v.26 no.2
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• pp.143-154
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• 2021

In this paper, we propose a method of compressing digital hologram standardized data provided by JPEG Pleno. In numerical reconstruction of digital holograms, the addition of random phases for visualization reduces speckle noise due to interference and doubles the compression efficiency of holograms. Holograms are composed of completely complex floating point data, and due to ultra-high resolution and speckle noise, it is essential to develop a compression technology tailored to the characteristics of the hologram. First, frequency characteristics of hologram data are analyzed using various wavelet filters to analyze energy concentration according to filter types. Second, we introduce the subband selection algorithm using energy concentration. Finally, the JPEG2000, SPIHT, H.264 results using the Daubechies 9/7 wavelet filter of JPEG2000 and the proposed method are used to compress and restore, and the efficiency is analyzed through quantitative quality evaluation compared to the compression rate.

• Journal of the Korea Computer Industry Society
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• v.2 no.12
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• pp.1609-1616
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• 2001

We present an autostereoscopic 3D display system using volume hologram. In this proposed system, the interference pattern of angular multiplexed plane reference and object beams are recorded into a volume hologram, which plays a role of guiding object beams of multi-view images into the desired perspective directions. For reconstruction, object beams containing the desired multi-view image information, which satisfy Bragg matching condition, are illuminated in the time-division multiplexed manner onto the crystal. Then multiple stereoscopic images are projected to the display plane for autostereoscopic 3D viewing. It is possible to make a high resolution multiview 3D display system independent upon the viewpoint.

• Korean Journal of Optics and Photonics
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• v.21 no.4
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• pp.146-150
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• 2010

In this paper we have applied phase conjugated holographyto DHM (digital holography microscopy) to remove phase aberration and noise. Generally,digital holographyincludes the phase information of the object, phase aberration terms introduced by the measurement system and noise terms (DC term and twin images). These aberrations and noise terms decrease the quality of the reconstructed phase image. We could obtain a conjugated hologram which includes only phase information of object. Experimentally we show that distortion of image and aberration of phase in a measurement system are removed using the conjugation hologram.