• Korean Journal of Optics and Photonics
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• v.2 no.1
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• pp.7-12
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• 1991

A nondestructive technique for measuring the refractive index of a simple lens is described. The shearing interferornetric technique is used for determining the focal length of a lens by immersing it in various liquids. The lens itself acts as autocollimator and decollimator. An equation for the defocusing error has been theoretically deduced and experimentally verified. The wave aberration has also been investigated for the different values of the focal length.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2006.05a
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• pp.205-210
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• 2006

본 논문에서는 간섭계와 직렬 위상 카드를 이용한 광 보안 시스템을 제안하였다. 먼저 원영상을 암호화하기 위해 원영상을 암호화하는 것이 아니라 원영상에 대한 이진 위상 컴퓨터형성홀로그램을 반복 알고리즘을 이용하여 구하고, 이진 위상 컴퓨터형성홀로그램과 무작위 생성된 위상 키 영상과의 XOR 연산을 통해 암호화된 영상을 구한다. 홀로그램의 복호화 과정은 암호화된 영상과 암호화시에 사용된 무작위 위상 영상 키를 직렬 정합시킨 후, 기준파와의 간섭에 의해 수행된다. 이때, 간섭패턴은 주위 환경에 상당히 민감하다. 그래서 광굴절매질의 자기위상공액성질을 이용하여 안정된 간섭패턴을 얻는다. 그리고 원영상은 복원된 홀로그램을 위상 변조한 후, 역푸리에 변환하여 최종적으로 구한다. 제안된 시스템에서는 암호화시에 사용된 무작위 키 영상 정보가 없으면 전혀 복원이 되지 않고, 키 영상을 달리함에 따라 복원되는 홀로그램의 패턴을 달리할 수 있으므로 차별화된 인증 시스템에 활용할 수 있다. 그리고 홀로그램의 성질에 의해 암호화된 영상이 일부 절단되더라도 원래의 영상을 복원할 수 있다.

• Journal of Integrative Natural Science
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• v.3 no.1
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• pp.33-37
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• 2010

The functionalized photonic crystals of porous silicon biosensor was prepared for the application as a label-free biosensor based on distributed Bragg reflector interferometer. Prepared distributed Bragg reflector of porous silicon biosensor displayed sharp reflection in the optical reflective spectra. The mean of construction of molecular architectures on distributed Bragg reflector of porous silicon surfaces was investigated for the step-by-step binding interaction with amines, biotin, avidin, and biotinylated protein A. The subsequent introduction of avidin, and biotinylated protein A resulted in the reflectivity shifted to longer wavelengths, indicative of a change in refractive indices induced by binding of biomolecules.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1593-1597
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• 2009

A biosensor has been developed based on induced wavelength shifts in the Fabry-Perot fringes in the visible reflection spectrum of appropriately derivatized thin films of porous silicon semiconductors. Porous silicon (PSi) was generated by an electrochemical etching of silicon wafer using two electrode configurations in aqueous ethanolic HF solution. Porous silicon displayed Fabry-Perot fringe patterns whose reflection maxima varied spatially across the porous silicon. The sensor system studied consisted of a mono layer of porous silicon modified with Protein A. The system was probed with various fragments of an aqueous Human Immunoglobin G (Ig G) analyte. The sensor operated by measurement of the Fabry-Perot fringes in the white light reflection spectrum from the porous silicon layer. Molecular binding was detected as a shift in wavelength of these fringes.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.12
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• pp.2032-2038
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• 1989

Single mode optical fiber interferometeric sensors using phase tracking homodyne detection are typically susceptible to environmentally indured temperature fluctuations and other types of disturbances. A simple and effective phase tracking feedback electronic circuit for compensator is described to achieve stabilizing signal output, maximum sensitivity and linearity in the fiber optic Mach-Zehnder infterferometer in the presence of differential phase drift. The phase tracking range of the piezoelectric cyclinder in the reference arm is \ulcorner.7 \ulcornerad and the prabe mass about 1 gram in the sensing arm was used for measurements of the gravity acceleration.

• Korean Journal of Optics and Photonics
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• v.8 no.3
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• pp.199-203
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• 1997

Fine displacement of spherical suface was detected and analyzed by Twyman-Green interferometer and the interferogram analysis using Fourier transform method. The surface profile was obtained from single interferogram by introducing the carrier freguency to the interferogram. The interferogram was processed in the spatial frequency domain by fast Fourier transform, and the phase distribution was obtained by inverse Fourier transform. The 3-dimensional distribution for the surface displacement was obtained. It was compared with the calculated surface displacement and the error was less than λ/10.

• Korean Journal of Optics and Photonics
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• v.4 no.3
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• pp.260-265
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• 1993

An in-situ stress measurement interferometer is constructed and used to measure the intrinsic stress in Ti$O_2$ thin films during their growth by ion-assisted deposition. It is found that the stress increases with the momentum transferred by the ion beam to the growing film and is fairly well agreed with Windischmann's model. The variation of the stress with thickness is qualitatively explained in terms of the balance between the compressive stress produced by the ion beam and the surface diffusion determined by the surface temperature.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.6
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• pp.995-1001
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• 1997

In this paper, a new positioning method with incoherence of white light is described and practically implemented to attach VCR heads on a drum very accurately. This method utilizes the Michelson Interferometer which uses white light with short coherence length as the light source to generate interference fringes only in case the optical path difference is shorter than about 2.mu.m. The course position of VCR heads and the fine are determined by appearance and visibility of interference fringes, respectively. The appearance are detected by an image processing technique using FFT(Fast Fourier Transform).

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.573-577
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• 2003

We report an effect of photon pairs on single-photon detection rates, while Hong-Ou-Handel's two-photon interference experiment is performed with photons produced in noncollinear type-I parametric down-conversion. Photon pairing behavior or spatial bunching is measured and shown to cause a decrease in the single photon counting rate. Such a dip is found to result from the fact that the single-photon timing resolution of photodetectors is much longer compared to the time interval between the two photons incident on the single-photon detector.

• Korean Journal of Optics and Photonics
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• v.3 no.1
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• pp.20-26
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• 1992

The fourier transform method of retrieving the phase of the test wavefront from a Twyman-Green interferometer was reviewed by numerical simulations and experiments. Of the two methods reviewed, Takeda's approach proved more reliable in reconstructing the deformation of the test surface. The application of this approach to a plane mirror showed the existence of the surface curvature, whose maximum deviation was about $\lambda$/6. The accuracy in the measurement was evaluated to be around $\lambda$/40.