• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.472-476
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• 2014

The Joint Transform Correlator (JTC) has been the most suitable technique for real time optical pattern recognition and target tracking applications. This paper proposes a new application of the JTC system for an analysis of the blurring effect of the optical images caused by a defocused lens. We present the relation between the correlation peak, optical transfer function (OTF), and the amount of blurring caused by focusing error. Moreover, we show a possibility of calibrating the blurred image by simply measuring the correlation peak.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.58-59
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• 2003

We propose the optical encryption system using two divided image to hide the original image and a joint transform correlator. The encryption procedure is performed by the Fourier transform of the product of each phase encoded image (divided phase images) and the same random phase image which is generated by computer processing. An autocorrelation term of joint transform correlator contributes to decrypt the original image. This system will be used in optical certification.

• Journal of the Optical Society of Korea
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• 제14권2호
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• pp.90-96
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• 2010

Joint transform correlator (JTC) has been the most suitable technique for real time pattern recognition. This paper proposes a new phase adjustment which adopts two steps of random phase adjustment in the spatial domain and additional phase adjustment in the Fourier domain. Simulated results are presented to show the optimum condition of the phase adjustment and the effect on the correlation peaks, the peak signal-to-noise ratio and the level of discrimination.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.357-362
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• 2010

The joint transform correlator (JTC) has been the best known technique for pattern recognition and identification. This paper proposes a new technique of fringe adjustment by adopting a sinusoidal amplitude-modulated iterative filter convolved with an interference fringe pattern in the joint power spectrum (JPS) domain. The comparison of our new technique and other techniques is presented to show that the newly proposed technique can successfully improve both the correlation peaks and the peak signal-to-noise ratio (PSNR). Simulated results of enhanced interference fringes are also presented.

• 전자공학회논문지A
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• 제31A권6호
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• pp.78-87
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• 1994

In this paper, a binary phase extraction joiont transform correlator (BPEJTC)system is proposed as a new phase-type optical correlator in which the correlation errors and DC component are dramtically reduced and optical efficiency and correlation performance are also improved by reconstructing the joint transform power spectrum (JTPS) of the conventional joint transform correlator (JTC)system form which the autocorrelation and crosscorrelation siganls generated in each self-plane are removed, and the binary phase function is extracted from the phase value of the reconstructed JTPS. Through some computer simulation and optical experimental results, the possibility of the implementation of the real-time multi-target tracking and recognition system is also suggested.

• 디지털산업정보학회논문지
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• 제5권2호
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• pp.51-76
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• 2009

In this paper, a new hybrid opto-digital multiple information hiding and real-time extracting system was suggested and implemented using a volume holographic optical correlator. The multiple information hiding system in which the multiple information can be hided in an arbitrary cover image was digitally implemented by using the combination of pseudo random sequence and Hadamard matrix. In addition, a real-time optical extraction system in which the hided multiple information in a cover image can be extracted in real-time was implemented by using a volume holographic optical correlator. In the VanderLugt-type holographic optical correlator used in this experiment, the multiful matched spatial filters corresponding each of the hided informations were recorded in a photorefractive crystal by using the moving window-based angular multiplexing scheme.

• 한국통신학회논문지
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• 제15권4호
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• pp.286-294
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• 1990

본 논문은 A/O광산관기의 실시간 신호 처리에 대하여 이론적으로 분석하고 실험을 통하여 시간적으로 두 신호의 상관함수를 얻는 방법을 연구하였다. 강도변조모드로 동작하는 본 광상관기는 종래의 광상관기에 비해 SNR을 높일 수 있었고 진폭변조모드로 동작하는 기존의 광상관기에 비해 시스템 구성이 간단하고 신호검출이 용이함을 보였다.

• 한국멀티미디어학회논문지
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• 제7권3호
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• pp.349-356
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• 2004

본 논문에서는 SA(simulated annealing) 알고리듬에 기반한 4-f 광 상관 시스템을 이용하여 실제적인 영상 보안 시스템을 제안하였다. 반복적인 SA알고리듬을 이용하여 이진 위상 성분을 갖는 암호화된 영상과 키 영상을 얻고, 4-f 광 상관 시스템을 이용하여 암호화된 영상과 키 영상과의 상관을 통해 복호화된 영상이 구해진다. 제안된 방법에서는 암호화된 영상 및 키 영상이 이진 위상 성분으로 구성되므로 광 보안 시스템을 구현하기 쉬운 장점이 있다. 그리고 만약 암호화된 영상을 암호화 시스템내에서 고정시키고, 키 영상 정보만을 달리 하면 서로 다른 영상을 복호화할 수 있으므로 차별화된 인증시스템에 응용할 수 있는 장점도 있다. 컴퓨터 시뮬레이션 결과는 두 영상(암호화 및 키 영상)의 이진 위상 성분에도 불구하고, 복호화영상이 생성됨을 보여준다.

• 전자공학회논문지D
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• 제35D권3호
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• pp.63-69
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• 1998

In this paper, a new input method is proposed to improve shift-invariant property of a photorefractive correlator andwe implemented real-time optical pattern recognition system using it. In the conventional photorefractive correlator, it is vrey difficult to satisfy the Bragg condition in the pattern recognition process. So, correlation peak is decreased heavily for the shift of input image. If a liquid crystal television(LCTV) without an anlyzer is used as input device, we can get the correlation result regardless of shift of input image because beam path is not changed during storage of holographic filter and correlation process. Also recording time of a holographic matched filter in photorefractive crystal is reduced and the correlation peak is increased because incident beam on the LCTV is transmitted completely. Therefore total optical efficiency is improved. We compared and analyzed the correlation results of proposed photorefractive correlator by computer simulation and optical experiment. We used a BaTiO$_{3}$ single crystal which has high diffraction efficiency in optical experiment.

• 한국광학회지
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• 제14권5호
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• pp.491-497
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• 2003

Joint transform correlator(JTC)를 기반으로 이진 암호화 키를 사용하는 광 암호화 시스템을 제시하였다. 이진 암호화 키는 Pixel-oriented CGH의 설계방법을 이용하여 제작하였고, 컴퓨터 모의 실험결과를 통하여 구현된 이진 암호화 키의 독립성 및 효능을 조사하였다. CGH방법으로 구현된 이진 암호화 키의 효능을 검증하기 위하여 홀로그래픽 메모리 기반의 광 암호화 장치를 구성하여 실험을 하였으며 그 결과 높은 암호화 가능성을 나타내었다.