• Title/Summary/Keyword: Optical fiber measurement

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In-process Measurement of Surface Profile using CCD (CCD를 이용한 인프로세스 표면형상의 계측)

  • 이기용;강명창;김정석;조인순
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.255-258
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    • 1995
  • Surface profile is an important paramerer to evaluate accuracy of machined worpiece. It is necessary to acquire this data by in-process measurement. Recent researchers have introduced Machine Vision technique to achieve it. But it is difficult to apply it to industry field yet. In this study, in-process measuring system of surface profile is developed using CCD camera. The effect of illuminance according to incident angle is investigated and surface profile from surface tester and illuminance graph are compared experimentally.

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Development of a Convergence Monitoring Method for Cylindrical Structures by Optical Fiber Bragg Grating Sensor (광섬유 FBG센서를 이용한 원주형 구조물의 2차원 상대변위 모니터링기법 개발)

  • Lho, Byeong-Cheol;Kim , Jong-Woo;Kang , Suck-Hwa
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.4
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    • pp.160-166
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    • 2006
  • Optical Fiber Bragg Grating sensor has a good performance to measure microscopic displacement which can measure strain of lining concrete and cylindrical structure like high intensity containment building and it can present many advantages like a corrosion resistance from the durability point of view. Then it can measure plane geometrical displacement of cylindrical structures with two-way displacement FBG sensor module. According to the test result, measurement of FBG sensor is better performance than other electric sensor system and 2D-level measurement. As a test result, Resolution of the two-way displacement sensor module with FBG sensors are more 10 times than other LVDT or 2D surveying.

Performance of Continuous-wave Coherent Doppler Lidar for Wind Measurement

  • Jiang, Shan;Sun, Dongsong;Han, Yuli;Han, Fei;Zhou, Anran;Zheng, Jun
    • Current Optics and Photonics
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    • v.3 no.5
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    • pp.466-472
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    • 2019
  • A system for continuous-wave coherent Doppler lidar (CW lidar), made up of all-fiber structures and a coaxial transmission telescope, was set up for wind measurement in Hefei (31.84 N, 117.27 E), Anhui province of China. The lidar uses a fiber laser as a light source at a wavelength of $1.55{\mu}m$, and focuses the laser beam on a location 80 m away from the telescope. Using the CW lidar, radial wind measurement was carried out. Subsequently, the spectra of the atmospheric backscattered signal were analyzed. We tested the noise and obtained the lower limit of wind velocity as 0.721 m/s, through the Rayleigh criterion. According to the number of Doppler peaks in the radial wind spectrum, a classification retrieval algorithm (CRA) combining a Gaussian fitting algorithm and a spectral centroid algorithm is designed to estimate wind velocity. Compared to calibrated pulsed coherent wind lidar, the correlation coefficient for the wind velocity is 0.979, with a standard deviation of 0.103 m/s. The results show that CW lidar offers satisfactory performance and the potential for application in wind measurement.

Implemeention and performance measurement of a novel in-service supervisory system for WDM transmission link (파장분할다중화방식 전송로의 In-service 감시를 위한 새로운 감시시스템의 구현 및 성능평가)

  • 김필한;윤호성;박남규;서재은;정기태;유기원;이규행
    • Korean Journal of Optics and Photonics
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    • v.12 no.2
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    • pp.129-134
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    • 2001
  • Novel supervisory system for WDM transmission link using conventional optical time domain reflectometry was presented. By modifying the structure of erbuim doped fiber amplifier to support bi-directional transmission at arDR pulse wavelength and launching the optical pulse into transmission link in the opposite direction of data signal propagation to avoid the distortion by cross-gain modulation, it is possible to monitor the WDM link in service. To prove the validity of proposed scheme, the supervision result of 2.5 Gbps $\times$ 8 channel WDM 320 km transmission system in service by arDR was presented. And power penalty due to monitoring was measured as smaller than 0.3 dB. .3 dB.

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Measurement of Material Properties of Composites under High Temperature using Fiber Bragg Grating Sensors (광섬유 브래그 격자 센서를 이용한 고온용 복합재료의 물성 측정)

  • 강동훈;박상욱;김수현;홍창선;김천곤
    • Composites Research
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    • v.16 no.6
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    • pp.41-47
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    • 2003
  • Composites are widely used for aircraft, satellite and other structures due to its good mechanical and thermal characteristics such as low coefficient of thermal expansion(CTE), heat-resistance, high specific stiffness and specific strength. In order to use composites under condition of high temperature, however, material properties of composites at high temperatures must be measured and verified. In this paper, material properties of T700/Epoxy were measured through tension tests of composite specimens with an embedded FBG sensor in the thermal chamber at the temperatures of RT, $100^{\circ}$, $200^{\circ}$, $300^{\circ}$, $300^{\circ}$. Through the pre-test of an embedded optical fiber, we confirmed the embedding effects of an optical fiber on material properties of the composites. Two kinds of specimens of which stacking sequences are [0/{0}/0]$_{T}$. and [$90_2$/{0}/$90_2$]. were fabricated. From the experimental results, material property changes of composites were successfully shown according to temperatures and we confirmed that fiber Bragg grating sensor is very appropriate to strain measurement of composites under high temperature.

Influence of Detailed Structure and Curvature of Woven Fabric on the Luminescence Effect of Wearable Optical Fiber Fabric (직물의 세부 구조 및 굴곡이 웨어러블 광섬유의 발광 효과에 미치는 영향)

  • Yang, Jin-Hee;Cho, Hyun-Seung;Kwak, Hwy-Kuen;Oh, Yun-Jung;Lee, Joo-Hyeon
    • Science of Emotion and Sensibility
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    • v.21 no.4
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    • pp.55-62
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    • 2018
  • The two main requirements of wearable optical fiber fabrics are that they must presuppose a high degree of flexibility and they must maintain the luminance effect in both flat and bent conformations. Therefore, woven optical fiber fabrics that satisfy the above conditions were developed by both weaving and by using computer embroidery. First, we measured the brightness of the wearable optical fiber fabric in the flat state at a total of 10 measurement points at intervals of 1 cm. Second, the wearable optical fiber fabric was placed horizontally on the forearm, where three-dimensional bending occurs, and the luminance values were recorded at the same 10 measurement points. For the woven fabric in the flat state, the maximum, minimum, average, and standard deviation luminance values were $5.23cd/m^2$, $2.74cd/m^2$, $3.56cd/m^2$, and $1.11cd/m^2$, respectively. The corresponding luminance values from the bent forearm were $7.92cd/m^2$ (maximum), $2.37cd/m^2$ (minimum), $4.42cd/m^2$ (average), and $2.16cd/m^2$ (standard deviation). In the case of the computer-embroidered fabric, the maximum, minimum, average, and standard deviation luminance values in the flat state were $7.56cd/m^2$, $3.84cd/m^2$, $5.13cd/m^2$, and $1.04cd/m^2$, respectively, and in the bent forearm state were $9.6cd/m^2$, $3.63cd/m^2$, $6.13cd/m^2$, and $2.26cd/m^2$, respectively. Therefore, the computer-embroidered fabric exhibited a higher luminous effect than the woven fabric because the detailed structure reduced light-loss due to the backside fabric. In both types of wearable optical fiber fabric the luminance at the forearm was 124% and 119%, respectively, and the light emitting effect of the optical fiber fabric was maintained even when bent by the human body. This is consistent with the principle of Huygens, which defines the wave theory of light, and also the Huygens-Fresnel-Kirchhoff principle, which states that the intensity of light increases according to the magnitude of the angle of propagation of the light wavefront (${\theta}$).

A study on the measurement of the current & voltage using Photoelastic effect of Optical Fiber (광섬유의 photoelastic효과를 이용한 전류및 전압의 측정에 관한 연구)

  • Choi, Do-In;Kim, Chang-Hyun;Kim, Ho-Seong
    • Proceedings of the KIEE Conference
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    • 1995.07c
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    • pp.1268-1270
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    • 1995
  • A method using photoelectric effect of a single-mode optical fiber, with a 632.8nm He-Ne laser, has been developed for the simultaneous measurment of current and voltage. The Magnetic stress for the current and the piezoelectric effect for voltage are utilized. It is found that the detector output voltage is proportional to the square of the applied current and the frequency of the output is twice of that of the applied current.

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Phase-extraction using Zero-Crossing detection in fiber-optic laser interferometry (영점검출을 이용한 광섬유형 레이저 간섭계의 위상추출)

  • Park, Hyoung-Jun;Lee, Jun-Ho;Song, Min-Ho
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2005.05a
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    • pp.426-430
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    • 2005
  • The fiber-optic interferometer which is a powerful application for nondestructive measurement techniques has many advantages such as capability of making portable system, easy optical arrangement, low optical loss. In spite of these advantages, this system has an environmental sensitivity of thermal drifts and vibrations. Against environmental perturbations and nonlinear characteristic of phase modulator, the accurate and fast ${\pi}/2$ phase stepping has been achieved by using zero-crossing detection. CCD camera trigger signal is generated at the 4 zero-crossing points. Our System has achieved up to 100 Hz of image capture speed and 0.6 mrad of accuracy of phase stepping, accuracy.

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A Study on Partial Discharge Measurement using Optical Fiber Sensors (광섬유 센서를 이용한 부분방전 측정연구)

  • Lee, June-Ho;Lee, Cheol-Kyou
    • Proceedings of the KIEE Conference
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    • 1998.11c
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    • pp.922-924
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    • 1998
  • In this paper, an optical fiber sensor(OF sensor) utilizing the principal of Mach-Zehnder interferometer were proposed to detect the partial discharge signals in insulating oil. At first the AC breakdown signals were detected to check the response of the OF sensor. The detected signals from OF sensor was consistent with that from current probe. After the response checking, simultaneous measurements and continuous recording were made of electrical and the OF sensor signals from partial discharge(PD) produced by IEC(b) electrode system immersed in insulating oil. The continuous recording made it possible to extract basic quantities of PD from the OF sensor signals, such as pulse phase and pulse amplitude distribution. Through the signal analysis, the absolute peaks of the OF sensor PD signal was found to be increased with the amplitude of electrical signals, and these results mean that there is a strong correlation between OF sensor and electrical PD signals. It was demonstrated that the OF sensor in this research had a possibility to detect the PD signals in power apparatus.

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