• Title/Summary/Keyword: random phase

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Double Encryption of Binary Image using a Random Phase Mask and Two-step Phase-shifting Digital Holography (랜덤 위상 마스크와 2-단계 위상 천이 디지털 홀로그래피를 이용한 이진 영상 이중 암호화)

  • Kim, Cheolsu
    • Journal of Korea Multimedia Society
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    • v.19 no.6
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    • pp.1043-1051
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    • 2016
  • In this paper, double encryption technique of binary image using random phase mask and 2-step phase-shifting digital holography is proposed. After phase modulating of binary image, firstly, random phase mask to be used as key image is generated through the XOR operation with the binary phase image. And the first encrypted image is encrypted again through the fresnel transform and 2-step phase-shifting digital holography. In the decryption, simple arithmetic operation and inverse Fresnel transform are used to get the first decryption image, and second decryption image is generated through XOR operation between first decryption image and key image. Finally, the original binary image is recovered through phase modulation.

Experimental demonstration of holographic storage with discrete random phase-code multiplexing

  • Park, Youn-Sup;Shin, Dong-Hak;Jang, Ju-Seog
    • Journal of the Optical Society of Korea
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    • v.4 no.1
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    • pp.43-47
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    • 2000
  • We studied experimentally a discrete random phase-code multiplexing technique for holographic data storage, which we believe can overcome some disadvantages of conventional random phase-code multiplexing adopting either a diffusion plate or a multimode fiber. Experimental demonstration is presented to show the potential usefulness and some characteristics of the discrete random phase-code multiplexing technique.

Sampling Phase Detector for NRZ Random Bit Synchronization (NRZ Random Bit 동기를 위한 표본 위상 검출기)

  • 박세현;박세훈
    • Journal of Korea Multimedia Society
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    • v.3 no.6
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    • pp.652-660
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    • 2000
  • This paper proposes a new type of sampling Phase Detector (SPD) for NRZ random bit synchronization circuit. The proposed SPD calculates the mean value of phase difference between bit interval of input signal and period of local reference. Simulated and experimental results show that the proposed SPD is applicable to the phase detector for NRZ random signal. finally the Random NRZ bit synchronization circuit. is designed and implemented by using SPD.

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Characteristics of encryption in optical memory using random phase mask (랜덤 위상 마스크를 이용한 광 메모리에서의 암호화 특성)

  • Choi, Jin-San;Yang, Byung-Choon;Lee, Byoung-Ho
    • Proceedings of the KIEE Conference
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    • 1999.11d
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    • pp.1128-1130
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    • 1999
  • Optical encoding method of images using random-phase encoding in both input and Fourier Planes was proposed by Javidi and his group, and the method was realized experimentally by Singh and his group with use of a photorefractive crystal and a phase conjugate wave.[1-2] Recently various techniques have been proposed theorically and experimentally. These include the method using one random-phase mask in the Fourier plane or two random-phase masks in the input and the Fresnel planes.[3] We demonstrate the difference and the problem of the methods using one or two random-phase masks in the Fourier or Fresnel plane. We perform the encoding and decoding in $LiNbO_3$ crystal using degenerate four-wave mixing.

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Practical Encryption and Decryption System using Iterative Phase Wrapping Method (반복적인 위상 랩핑 방법을 이용한 실질적인 암호화 및 복호화 시스템)

  • Seo, Dong-Hoan;Lee, Sung-Geun;Kim, Yoon-Sik
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.6
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    • pp.955-963
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    • 2008
  • In this paper, we propose an improved practical encryption and fault-tolerance decryption method using a non-negative value key and random function obtained with a white noise by using iterative phase wrapping method. A phase wrapping operating key, which is generated by the product of arbitrary random phase images and an original phase image. is zero-padded and Fourier transformed. Fourier operating key is then obtained by taking the real-valued data from this Fourier transformed image. Also the random phase wrapping operating key is made from these arbitrary random phase images and the same iterative phase wrapping method. We obtain a Fourier random operating key through the same method in the encryption process. For practical transmission of encryption and decryption keys via Internet, these keys should be intensity maps with non-negative values. The encryption key and the decryption key to meet this requirement are generated by the addition of the absolute of its minimum value to each of Fourier keys, respectively. The decryption based on 2-f setup with spatial filter is simply performed by the inverse Fourier transform of the multiplication between the encryption key and the decryption key and also can be used as a current spatial light modulator technology by phase encoding of the non-negative values. Computer simulations show the validity of the encryption method and the robust decryption system in the proposed technique.

New Random and Additional Phase Adjustment of Joint Transform Correlator

  • Jeong, Man-Ho
    • Journal of the Optical Society of Korea
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    • v.14 no.2
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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.

Key Phase Mask Updating Scheme with Spatial Light Modulator for Secure Double Random Phase Encryption

  • Kwon, Seok-Chul;Lee, In-Ho
    • Journal of information and communication convergence engineering
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    • v.13 no.4
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    • pp.280-285
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    • 2015
  • Double random phase encryption (DRPE) is one of the well-known optical encryption techniques, and many techniques with DRPE have been developed for information security. However, most of these techniques may not solve the fundamental security problem caused by using fixed phase masks for DRPE. Therefore, in this paper, we propose a key phase mask updating scheme for DRPE to improve its security, where a spatial light modulator (SLM) is used to implement key phase mask updating. In the proposed scheme, updated key data are obtained by using previous image data and the first phase mask used in encryption. The SLM with the updated key is used as the second phase mask for encryption. We provide a detailed description of the method of encryption and decryption for a DRPE system using the proposed key updating scheme, and simulation results are also shown to verify that the proposed key updating scheme can enhance the security of the original DRPE.

The effect of 1/f Noise Caused by Random Telegraph Signals on The Phase Noise and The Jitter of CMOS Ring Oscillator (Random Telegraph Signal에 의한 1/f 잡음이 CMOS Ring Oscillator의 Phase Noise와 Jitter에 미치는 영향)

  • 박세훈;박세현;이정환;노석호
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05b
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    • pp.682-684
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    • 2004
  • The effect of 1/f noise by the random telegraph signal(RTS) on the phase noise and the jitter of CMOS ring Oscillator is investigated. 10 parallel piece-wise-linear current sources connected to each node model the RTS signals. The In, the power spectral density and the jitter of output of the ring oscillator are simulated as functions of the amplitude and time constant of RTS current source. It is confirmed that the increase of amplitude of RTS is directly related to the increase of the width of phase noise md the value of jitter. The shorter the time constant is, the wider width of FET peak and the larger value of cycle to cycle jitter are.

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Image Authentication Using Only Partial Phase Information from a Double-Random-Phase-Encrypted Image in the Fresnel Domain

  • Zheng, Jiecai;Li, Xueqing
    • Journal of the Optical Society of Korea
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    • v.19 no.3
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    • pp.241-247
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    • 2015
  • The double-random phase encryption (DRPE) algorithm is a robust technique for image encryption, due to its high speed and encoding a primary image to stationary white noise. Recently it was reported that DRPE in the Fresnel domain can achieve a better avalanche effect than that in Fourier domain, which means DRPE in the Fresnel domain is much safer, to some extent. Consequently, a method based on DRPE in the Fresnel domain would be a good choice. In this paper we present an image-authentication method which uses only partial phase information from a double-random-phase-encrypted image in the Fresnel domain. In this method, only part of the phase information of an image encrypted with DRPE in the Fresnel domain needs to be kept, while other information like amplitude values can be eliminated. Then, with the correct phase keys (we do not consider wavelength and distance as keys here) and a nonlinear correlation algorithm, the encrypted image can be authenticated. Experimental results demonstrate that the encrypted images can be successfully authenticated with this partial phase plus nonlinear correlation technique.

A Study on Phase-Multiplexed Volume Hologram using Spatial Light Modulator (공간광변조기를 이용한 위상다중화 체적 홀로그램에 관한 연구)

  • Jo, Jong-Dug;Kim, Kyu-Tae
    • 전자공학회논문지 IE
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    • v.44 no.3
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    • pp.23-34
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    • 2007
  • For an effective phase multiplexing in a volume holographic system, four types of phase code, pseudo random code(PSC), Hadamard matrix(HAM), pure random code(PRC), equivalent random code(ERC), used as reference beams are generated. In case of $32{\times}32$ address beam, a phase error with 0%, 5%, 10%, 15%, 20%, and 25% error rate, is purposely added to the real phase values in order to consider the practical SLM's nonlinear characteristics of phase modulation in computer simulation. Crosstalks and SNRs(signal-to-ratio) are comparatively analyzed for these phase codes by the auto-correlation and cross-correlation. PSC has the lowest cross-correlation mean value of 0.067 among four types of phase code, which means the SNR of the pseudo random phase code is higher than other phase codes. Also, the standard deviation of the pseudo random phase code indicating the degree of recalled data degradation is the lowest value of 0.0113. In order to analyze the affect by variation of pixel size, simulation is carried out by same method for the case of $32{\times}32$, $64{\times}64$, $128{\times}128$, $256{\times}256$ address beams.