• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.10
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• pp.1576-1583
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• 1989

In this paper, we describe real-time optical implementation of the Hopfield neural network model for two-dimensional associative memory by using commercial LCTV and Multifocus For real-time processing capability, we use LCTV as a memory mask and a input spatial light modulator. Inner product between input pattern and memory matrix is processed by the multifocus holographic lens. The output signal is then electrically thresholded fed back to the system input by 2-D CCD camera. From the good experimental results, the proposed system can be applied to pattern recognition and machine vision in future.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.42-54
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• 2023

It is an important issue to compress huge holographic data in a digital format. In particular, research on the compression of phase-only holograms for commercialization is noteworthy. Conventional video coding standards optimized for natural images are not suitable for compressing phase signals, and neural network-based compression model that can be optimized for phase signals can achieve high performance, but has a memory issue in learning high-resolution holographic data. In this paper, we show that by applying a block-based learned image compression model that can solve memory problems to phase-only holograms, the proposed method can demonstrate significant performance improvement over standard codecs even under the same conditions as block-based. Block-based learned compression model can provide compatibility with conventional standard codecs, solve memory problems, and can perform significantly better against phase-only hologram compression.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.638-644
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• 2002

In this paper, we implemented a three dimensional image display system using stereogram and holographic optical memory techniques which can store many images and reconstruct them automatically. In this system, to store and reconstruct stereo images, incident angle of reference beam must be controlled in real time, so we used BPH(binary phase hologram) and LCD(liquid crystal display) for controlling reference beam. The reference beams are acquired by Fourier transform of BPHs which designed with SA(simulated annealing)algorithm, and the BPHs are represented on the LCD with the 0.05 seconds time interval using application software for reconstructing the stereo images. And input images are represented on the LCD without polarizer/analyzer for maintaining uniform beam intensities regardless of the brightness of input images. The input images and BPHs are edited using application software(Photoshop) with having the same recording scheduled time interval in storing. The reconstructed stereo images are acquired by capturing the output images with CCD camera at the behind of the analyzer which transforms phase information into brightness information of images. In output plane, we used a LCD shutter that is synchronized to a monitor that display alternate left and right eye images for depth perception. We demonstrated optical experiment which store and reconstruct four stereo images in BaTiO$_3$ repeatedly using the proposed holographic optical memory techniques.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.128-129
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• 2002

정보, 전산 산업의 발달이 급속하게 이루어짐에 따라 필연적으로 정보의 저장 및 입출력에 관계된 정보저장장치는 용량의 대량화, 입출력 속도의 고속화가 요구된다. 홀로그램을 이용한 정보저장장치는 데이터의 기록·재생의 원리상 체적 홀로그램의 원리를 이용하여 한 점에 대량의 면정보를 저장할 수 있는 페이지 지향적인 메모리(Page-oriented Memory)로써 입출력 방식으로 병렬 데이터 처리방식을 사용하므로 근본적으로 입출력 속도를 초고속화 할 수가 있으며, 기계적인 구동 부를 배제한 시스템이 가능하므로 데이터 접근 시간도 매우 빠르게 할 수 있다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.138-141
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• 2002

광굴절 결정체가 홀로그래픽 저장 매개체로 이용될 수 있음이 Chen에 의해 제시된 이후, 광굴절 결정체는 대용량 광메모리로서 관심의 초점이 되었다. 그리하여 홀로그래픽 기법을 이용하여 이미지를 광굴절 결정체에 저장시키는 방법에 대한 연구가 광범위하게 이루어져 왔다. 보통 여러개의 홀로그램을 저장 매체인 광굴절 결정체에 중첩하여 저장하는 경우, 먼저 기록된 홀로그램이 뒤이어 기록되는 홀로그램들에 의해서 지워지기 때문에 먼저 기록된 홀로그램의 복원이 어려워진다. (중략)

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.293-296
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• 1999

본 논문에서는 위상 다중화 홀로그래픽 메모리 시스템에서 사용될 최적의 위상코드를 구현하기 위해 기존에 위상 다중화에 많이 사용되고 있는 Hadamard 행렬을 비롯한 여러 행태의 랜덤 위상코드들의 상호상관 값에 의한 Cross talk의 영향 및 신호대 잡음비, 그리고 어드레스 갯수를 비교 분석하였다.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.210-217
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• 2000

본 논문에서 높은 에러 정정 성능을 갖는 디지털 홀로그래픽 광메모리 시스템을 구현하였다. 에러 정정 성능을 높이기 위해서, 비트에러 정정 능력을 갖고 있는 Hamming(12, 8, 1)코드와 산발 및 연집에러 정정 능력이 뛰어난 Reed-Sokomon 코드로 구성된 hydrid 코딩기법을 채용하였다. 입력 데이터로는 Lena 영상 (256$\times$256bytes)을 책택하였으며, 영상압축기법(JPEG)을 도입하였다. Hybrid 코딩과 영상압축기법을 조합한 광메모리 시스템의 시험결과가 제시되었다.

• The Journal of the Korea Contents Association
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• v.12 no.9
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• pp.40-47
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• 2012

Existing art, media art, accompanied by a new path of awareness and perception instrumentalized by the human body, creating a new way to watch the interaction is proposed. Western art way to create visual images of the point cloud that represented a form that is similar to the Pointage. This traditional painting techniques using digital technology means reconfiguration. In this paper, a new appreciation of fusion of aesthetic elements and digital technology, making the point cloud in the form of video. And this holographic film projection of the spectator, and gestures to interact with the video content is presented. A Process of making contents is intent planning, content creation, content production point cloud in the form of image, 3D gestures for interaction design process, go through the process of holographic film projection. Visual and experiential content of memory recall process takes place in the consciousness of the people expressed. Complete the process of memory recall, uncertain memories, memories materialized, recalled. Uncertain remember the vague shapes of the point cloud in the form of an image represented by the image. As embodied memories through the act of interaction to manipulate images recall is complete.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.3
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• pp.49-52
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• 2001

The derivatives of spironaphthooxazine gause photoisomerization when they are illuminate with UV light. We investigated the photoisomerization of spironaphthooxazine derivatives for holographic memory. Langmuir-Blodgett (LB) films contain amphiphile spironaphthooxazine derivatives which can be applied in molecular devices by a change of molecular level energy and a refractive index. In order to investigate the photoisomerization of spironaphthooxazine derivatives at the air/water energy and a refractive index. In order to investigate the photoisomerization of spironaphthooxazine derivatives at the air/water interfaces, spironaphthooxazine derivatives with side alkyl chains were synthesized. The films of the spironaphthooxazine derivatives were characterized by the measurement of UV/vis spectroscopy, Brewster Angle Microscopy (BAM) and Atomic Force Microscopy (AFM). The monolayers of the spironaphthooxazine derivatives mixed with stearic acid were stable at the air/water interface and visualized by the measurement of BAM. The spironaphthooxazine derivative monolayers on the glass surface showed the maximum efficiency of diffraction as 0.99% by the measurement of holography.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.2
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• pp.22-27
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• 2000

We present a sequential stereoscopic display system using volume holographic storage. Multiple angular multiplexed stereoscopic image pairs are recorded into a photorefractive crystal that can store data with high density, transfer them with high speed, and select a randomly chosen data element. The reference beam with Bragg selectivity is scattered by the index grating and the diffracted beams are propagating along the directions of the stereoscopic image pairs. The images are to be suitably projected on the left and right display plane sequentially for stereoscopic video viewing.