• Title, Summary, Keyword: Optical correlator

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Phase-based virtual image encryption and decryption system using Joint Transform Correlator

  • Seo, Dong-Hoan;Cho, Kyu-Bo;Park, Se-Joon;Cho, Woong-Ho;Noh, Duck-Soo;Kim, Soo-Joong
    • Proceedings of the IEEK Conference
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    • pp.450-453
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    • 2002
  • In this paper a Phase-based virtual image encryption and decryption techniques based on a joint transform correlator (JTC) are proposed. In this method, an encrypted image is obtained by multiplying a phase-encoded virtual image that contains no information from the decrypted image with a random phase. Even if this encryption process converts a virtual image into a white-noise-like image, the unauthorized users can permit a counterfeiting of the encrypted image by analyzing the random phase mask using some phase-contrast technique. However, they cannot reconstruct the required image because the virtual image protects the original image from counterfeiting and unauthorized access. The proposed encryption technique does not suffer from strong auto-correlation terms appearing in the output plane. In addition, the reconstructed data can be directly transmitted to a digital system for real-time processing. Based on computer simulations, the proposed encryption technique and decoding system were demonstrated as adequate for optical security applications.

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Deformation Invariant Optical Correlator Using Photorefractive Medium (광굴절 매질을 이용한 공간계 불변 광상관기에 관한 연구)

  • Kim, Ran-Sook;Ihm, Jong-Tae;Son, Hyon;Park, Han-Kyu
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.6
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    • pp.97-101
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    • 1989
  • Scale and rotation invariant polar-logarithmic coordinate transformation is used to achieve deformation invariant pattern recognition. The coordinate transformation is produce by a computer generated hologram (CGH). The mask fabricated by a photo (UV light) pattern generator for the 1nr-$theta$ coordinate transformation is made of the CGH whose transmission function is derived by the use of Lee's method. The optically produced coordinate transformed function is derived by the use of Lee's method. The optically produced coordinate transmission input pattern is interfaced on real-time holography. Variations of autocorrelation for scaled and rotated input patterns are suggested experimentally using implemented optical correlator.

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광패턴 인식을 위한 pSDF와 이진 결합 변환 상관기의 구현

  • 정창규;김남수;조동래;박한규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.15 no.8
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    • pp.678-688
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    • 1990
  • In this paper, pSDF-based referance image is realized. Using BJTC(binary joint transform correlator) as the spatial plane correlator, optical pattern recognition for intraclass indentification is performed. Computer simulation shows that the correlation performance of BJTC is superior to that of JTC. Experimental results using BJTC reveal that correlation peak intensity is constant within the error range from 4.1% to 9.6% in intraclass indentification.

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Opto-Digital Implementation of Multiple Information Hiding & Real-time Extraction System (다중 정보 은폐 및 실시간 추출 시스템의 광-디지털적 구현)

  • 김정진;최진혁;김은수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.1C
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    • pp.24-31
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    • 2003
  • In this paper, a new opto-digital multiple information hiding and real-time extracting system is implemented. That is, multiple information is hidden in a cover image by using the stego keys which are generated by combined use of random sequence(RS) and Hadamard matrix(HM) and these hidden information is extracted in real-time by using a new optical correlator-based extraction system. In the experiment, 3 kinds of information, English alphabet of "N", "R", "L" having 512$\times$512 pixels, are formulated 8$\times$8 blocks and each of these information is multiplied with the corresponding stego keys having 64$\times$64 pixels one by one. And then, by adding these modulated data to a cover image of "Lena"having 512$\times$512 pixels, a stego image is finally generated. In this paper, as an extraction system, a new optical nonlinear joint transform correlator(NJTC) is introduced to extract the hidden data from a stego image in real-time, in which optical correlation between the stego image and each of the stego keys is performed and from these correlation outputs the hidden data can be asily exacted in real-time. Especially, it is found that the SNRs of the correlation outputs in the proposed optical NJTC-based extraction system has been improved to 7㏈ on average by comparison with those of the conventional JTC system under the condition of having a nonlinear parameter less than k=0.4. This good experimental results might suggest a possibility of implementation of an opto-digital multiple information hiding and real-time extracting system.

Implementation of Spatial Light Modulator(SLM) using a Commercial LCD Beam Projector

  • Ko, Jung-Hwan;Lee, Jae-Soo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.9
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    • pp.1-10
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    • 2006
  • In this paper, a new high resolution XGA-SLM is implemented through modification of a commercial TFT-LCD beam projector and its optical modulation characteristics as a spatial light modulator(SLM) is also analyzed. First, the optics module, projection lamp and fans are removed from a commercial beam projector and instead some electric circuits to compensate their removal are manufactured and then, by inserting them into the beam projector, a new XGA-SLM is finally implemented. Second, from some optical experimental results, this TFT-SLM is found to have a good optical linearity in amplitude and phase modulation characteristics as a function of the input gray levels. Especially, through implementation of a binary phase-type correlator such as BPEJTC by using the suggested TFT-LCD panel, the implemented SLM is proposed as a new relatively low-cost and high resolution SLM for optical information processing.

Proposal of optical subscriber access network using optical CDMA method with optical switches (광 스위치를 이용한 광 CDMA 방식에 의한 광 가입자 액세스 망의 제안)

  • Park, Sang-Jo;Kim, Bong-Kyu
    • The KIPS Transactions:PartC
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    • v.10C no.3
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    • pp.317-324
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    • 2003
  • In this paper, we propose the ATM based Passive Optical Network (PON) using the optical CDMA scheme with optical switches and PN codes in time domain. We also propose the bipolar optical receiving correlator for PN codes. As optical CDMA is performed by driving directly an optical switch on-off switching with PN codes, the number of distinct code sequences can be increased and the flexibility in assigning PN codes can be improved. Finally we theoretically analyze the signal-to-interference -plus-noise ratio and the bit error probability of regenerated signal and compare the performance of proposed scheme compared with ATM based PON using conventional optical CDMA with optical delay lines.

Acousto-Optical Third Order Correlator Using 2-D Ultrasonic Diffractor Cell (2차원 초음파 회절격자를 이용한 음향-광3차 상관기의 구성)

  • Jang, Gyeong-Yeong;Sato, Takuso
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.1
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    • pp.206-213
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    • 1996
  • Third order correlation funciton is to be advantageous to detect unique features embedded in various random signals that are undetectable with second order correlation or power spectrum. In this paper, we will introduce optical modulator which consists of a laser light source, 2-dimensional ultrasonic diffractor cell with signal controlling circuitry, and a CCD camera connected to personal computer for image processing. With this modulator, the third order correlaiton pattern of signal can be immediately obtained at the camera due to parallel nature of optical computing.

Biometrical Information Security by Using Optical Visual Cryptography (광시각암호를 이용한 생체정보보호)

  • 이상이;류충상;이승현
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.760-763
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    • 2004
  • We propose a biometrical information security method based on Optical Visual Cryptography in that a fingerprint data is processed by Secret Sharing method taking into account the Optical Visual Cryptography and a part of shared data transmitted through an open network. Whenever necessary the owner or the fingerprint can be authenticated by submitting his fingerprint with the other shared information.

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Fingerprint identific ation based on optical visual cryptography (광 비쥬얼 크립토그래피 를 이용한 지문인식)

  • Lee, Seng-Hyun
    • Journal of the Korea Computer Industry Society
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    • v.5 no.9
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    • pp.1069-1078
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    • 2004
  • We propose an individual authentication method based on optical visual cryptography in thata fingerprint data is processed by secret sharing method taking into account the optical visual cryptograph and a part of shared data transmitted through an open network. Whenever it is necessary, submitting his fingerprint with the other shared information can authenticate the owner of the fingerprint. The system efficiently identifies fingerprints through optical correlation, regardless of difficulties of acquisition of exact fingerprint imagein the various environments.

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Capacity Analysis of M-ary PPM UWB System In Optical Fiber over AWGN (AWGN Optical Fiber에서 M-ary PPM UWB 시스템의 채널용량 분석)

  • Im, Joon-Soon;Shin, Myung-Gon;Kim, Tae-Woong;Park, Seung-Kwon
    • Proceedings of the IEEK Conference
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    • pp.201-204
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    • 2005
  • In this paper, based on an extended model containing correlator and soft decision decoding, the capacity is evaluated in the single-user case when the inputs are equiprobable. With this method, we adjusted optical communication over AWGN. It is found that only when bit- signal-to-noise ratio (bit-SNR) is high enough, larger M leads to higher capacity; and for a specific M, the optimal values of PPM time offset parameter Td, which maximize the capacity, are independent of bit-SNR. In this paper, the capacity of UWB system in optical fiber over AWGN is proven to improve 1.73 times larger than AWGN channel Capacity.

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