• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.792-796
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• 2003

In this paper, to detect external sound frequency on the latticed structure, fiber optic sensor net using Sagnac interferometer was fabricated and tested. The latticed structure fabricated with dimension of 50cm in width and 50cm in height, the optical fiber, 50m in length, distributed and fixed on the latticed structure. Single mode fiber, a laser with 1,550nm in wavelength, 2${\times}$2 coupler were used. External sound signal applied to the fiber optic sensor net and the detected optical signals were compared and analyzed to the detected microphone signals against time and frequency domain. Based on the experimental results, fiber optic sensor net using Sagnac interferometer detected external sound frequency, effectively. This system can be expanded to the structural health monitoring system.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권11호
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• pp.622-626
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• 2000

In this paper, an optical fiber sensor(OF sensor) utilizing the principal of Sagnac interferometer was proposed to detect the discharge signals. The needle-sphere electrode system in insulating oil generated the signals. The performance of OF sensor was checked by sinusoidal calibration signal generated by PZT actuator at 198KHz. The detected discharge signals consisted of acoustic signal and the electrical noise. The noise signal could be removed by digital low pass filter. It was demonstrated that the OF sensor in this research had a possibility to detect the discharge signals in power apparatus.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.436-437
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• 2005

3-dimension object's feature measurement is used several industrial field to produce for examination of demanded high quality products by using optical measurement method. 3-dimension object's feature measurement is separated surface scanning and surface non-scanning. In this research, we illuminated interfero-pattern to object, it was constructed with Michelson interferometer by using laser is one of surface non-scanning method. And we extracted phase-map, it is one of featural measurement analysis of 3-dimensional object by using a phase shifting theory.

• 한국소음진동공학회논문집
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• 제14권7호
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• pp.569-576
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• 2004

In this paper, to detect external sound frequencies on the latticed structure, fiber optic sensor net using Sagnac interferometer was fabricated and tested. The latticed structure was fabricated with a dimension of 50 cm in width and 50 cm in height. The optical fiber of 50m in length was distributed and fixed on the surface of the latticed structure. Single mode fiber, a laser with 1,550 nm in wavelength, 2 ${\times}$ 2 coupler were used. External sound signal, 240 Hz, 495 Hz, 1.445 kHz, 2k Hz, applied to the fiber optic sensor net and the detected optical signals were compared to the detected microphone signals against time and frequency domains. Based on the experimental results, fiber optic sensor net using Sagnac interferometer detected external sound frequency, effectively. This system can be expanded to the structural health monitoring system.

• Journal of the Optical Society of Korea
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• 제7권2호
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• pp.113-118
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• 2003

A two-photon interference experiment is presented in which an entangled pair of photons generated from a parametric down-conversion was incident on two input ports of a Mach-Zehnder interferometer. The experiment was carried out using two photon coincidence detection with two detectors at the two output ports of the interferometer. The measured coincidence counts exhibit an interference effect with visibility of 0.75 at simultaneous inputs and 0.38 at inputs with different arrival times according to the degree of photon number entanglement.

• 천문학회보
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• 제44권1호
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• pp.58.3-58.3
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• 2019

Optical intensity interferometry, developed in the 1950s, is a simple and inexpensive method for achieving angular resolutions on microarcsecond scales. Its low sensitivity has limited intensity interferometric observations to bright stars so far. Substantial improvements are possible by using avalanche photodiodes (APDs) as light detectors. We present here the results of laboratory measurements with a prototype astronomical intensity interferometer using APDs in continuous ("linear") detection mode - arguably, the first of its kind. We used two interferometer configurations, one with zero baseline and one with variable baseline. Using a superluminous diode as light source, we unambiguously detected Hanbury Brown-Twiss photon-photon correlations at very high significance. From measuring the correlation as function of baseline, we measured the angular diameter of the light source, in analogy to the measurement of the angular diameter of a star. Our results demonstrate the possibility to construct large astronomical intensity interferometers that can address a multitude of astrophysical science cases.

• 한국정밀공학회지
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• 제14권6호
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• pp.128-134
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• 1997

Holographic interferometry is a useful whole-field nondestructive tesing method for measuring deformations and vibrations of engineering structure. In practical way most holographic interferometer uses a diverging beam, a point light source. When an oject is relatively small, the optical arrangement using a collimated light source has no difficulty technically but for a large object the collimated beam connot be applied anymore practically. In this paper we calculate the error of measured displacement from the sensi- tivity vector dominated by the geometry of optical arrangement for holographic interferometer and show the result with 2-D plots. A plane surface and a cylindrical surface were chosen as objects to be measured and the results from the cases of a diverging and a collimated beams were compared and analyzed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.849-850
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.501-502
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• 2009

• 융합신호처리학회논문지
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• 제2권3호
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• pp.86-92
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• 2001

미소 단위로 이동하는 물체의 이동 거리를 측정하기 위한 정밀 측정기기, 반도체 제조 장치, 공작기계 등의 위치 제어는 매우 중요한 요건이며, 이러한 장치들의 이동거리 측정에 대한 정확도는 전체 시스템의 성능을 좌우하게 된다. 따라서 정밀기기에서 이동 거리를 고정밀도로 측정할 수 있는 센싱 디바이스가 요구되며, 여기에는 레이저 간섭계의 분해능에 준하는 분해능을 갖고, 경제성 및 디지털 인터페이스에 대한 장점을 갖는 광학식 엔코더가 사용될 수 있다. 본 논문에서는 이동 거리를 측정하기 위해 회절 원리를 기초로한 고분해능 및 디지털 인터페이스가 용이한 간섭계형 리니어 스케일을 실험적으로 구성하였다. 그리고 이 리니어 스케일에서 발생된 간섭 신호는 제작된 광 검출기와 신호처리 회로를 통해 디지털화하였다. 그 결과 실험적으로 구성된 간섭계형 리니어 스케일은 스케일의 이동에 대하여 어떠한 분주 회로도 추가하지 않고, 단지 쉬운 광학적 구성으로 0.5$\mu\textrm{m}$의 분해능을 얻었다.