• Current Optics and Photonics
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• 제2권2호
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• pp.140-146
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• 2018

In this paper, mesoscale optical surface structures are found to possess both geometric and wave optics features. The study reveals that geometric optic analysis cannot correctly predict the experimental results of light transmission or reflection by mesoscale optical structures, and that, for reliable analyses, a hybrid approach incorporating both geometric and wave optic theories should be employed. By analyzing the transmission patterns generated by the mesoscale periodic pyramid prism plates, we show that the wave optic feature is mainly ascribed to the edge diffraction effect and we estimate the relative contributions of the wave optic diffraction effect and the geometric refraction effect to the total scattering field distribution with respect to the relative dimension of the structures.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.273-277
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• 2003

A general process of electronic assembly is composed of a series of geometric alignments and bonding/screwing processes. After assembly, the function is tested in a following process of inspection. However, assembly of micro-optic devices requires both processes to be performed in equipment. Coarse geometric alignment is made by using vision and optical function is improved by the following fine motion based on feedback of tunable laser interferometer. The general system is composed of a precision robot system for 3D assembly, a 3D vision guided system for geometric alignment and an optical feedback system with a tunable laser. In this study, we propose a new fast alignment algorithm of micro-optic devices for both of visual and optical alignments. The main goal is to find a fastest alignment process and algorithms with state-of-the-art technology. We propose a new approach with an optimal sequence of processes, a visual alignment algorithm and a search algorithm for an optimal optical alignment. A system is designed to show the effectiveness and efficiency of the proposed method.

• Transactions on Electrical and Electronic Materials
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• 제9권2호
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• pp.84-88
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• 2008

In this paper, we analyze the errors associated with electric field interference for fiber-optic voltage sensors working in a three-phase electric system. For many practical conductor arrangements, the electric filed interference may cause errors unacceptable for the accuracy requirements of the sensors. We devised a real time compensation method for the interference by introducing geometric and weight factors. We realized the method using simple electronic circuits and obtained the real time compensated outputs with errors of 1 %.

• 센서학회지
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• 제15권1호
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• pp.40-46
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• 2006

This paper presents a novel fiber optic accelerometer system for monitoring vibration of large-size structures. The system is composed of one (or multiple) sensor head, a light control unit and a signal processing unit. The sensing mechanism of the sensor head is based on a novel integration of the moire fringe phenomenon with fiber optics to achieve a robust performance in addition to its immunity to EM interference, easy cabling, and low cost. In this paper, a prototype of the fiber optic accelerometer system has been developed successfully. A low-cost light control unit has been developed to drive the system's optic and electronic components. A unique algorithm has also been developed to derive the sensor's acceleration from the raw signals of the light control unit; it is implemented via a separate signal processing unit. Finally, the shaking table tests successfully demonstrate the performance and the potential of the moire fringe fiber optic sensor system to monitor the health of civil infrastructures.

• Journal of Magnetics
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• 제12권4호
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• pp.156-160
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• 2007

In this paper, we analyze the errors associated with magnetic field interference for fiber-optic current sensors working in a three-phase electric system and provide a solution to compensate the interference. For many practical conductor arrangements, the magnetic filed interference may cause errors unacceptable for the accuracy requirements of the sensors. We devised a real time compensation method for the interference by introducing geometric and weight factors. We realized the method using simple electronic circuits and obtained the real time compensated outputs with errors of ${\pm}1%$.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1064-1069
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• 2004

Ceramic ferrules which are major parts of the fiber optic connectors are requiring high precisions in grinding. After grinding, it is the problem that subsurface damages cannot be removed. The objective of this study was to analyze the grinding force and the associated stress generated in a ceramic ferrule during cylindrically external griding using finite element analysis(FEA). A two-dimensional finite element model was constructed with the grinding parameters and the mechanical properties of the ferrule as input variables. The size of the geometric model was the same with ceramic ferrule. The experimental results are investigated by SEM photograph and compared with the results from FEM. The result of FEA showed a good agreement with that of experiment.

• 한국정밀공학회지
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• 제31권12호
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• pp.1133-1139
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• 2014

This paper proposes a simple method to improve a sensitivity of a straightness measurement system for a linear stage, which is applied to a system based on a geometric optic method. An optical system for this method is composed of a corner-cube retro-reflector, a ball-lens and a twodimensional position sensitive detector (2D PSD). The effectiveness of the proposed method was examined theoretically, and verified experimentally using a prototype measurement system. The results show that the measuring sensitivity was dependent on the size of the ball-lens and the setup position of PSD from the ball-lens, and that the proposed method is efficient method to improve the measuring sensitivity.

• 한국정밀공학회지
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• 제23권5호
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• pp.103-110
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• 2006

Automatic optical alignment modules are a key technology in optical communication system. However, the optic component assembly depends highly on manual or semi-automated alignment process. In this paper, a novel alignment mechanism with minimum degree-of-freedom has been designed and theoretical models are derived from geometric optical characteristics on collimators, optical filters and optical ray alignment. The automatic alignment control algorithm has been newly developed based on the mechanism and models, and then we make fast, precise and reliable alignment through the algorithm. The reliability of developed modules has been verified with various simulations and performance evaluations.

• 한국광학회지
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• 제33권6호
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• pp.317-323
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• 2022

본 논문에서는 투명한 물질의 두께를 측정하기 위한 방법으로 기하 위상 렌즈 기반의 색공초점 센서를 개발하고, 성능 개선을 위한 보정 방법을 제시한다. 일반적인 색공초점 센서의 복잡한 설계로 인한 한계를 극복하기 위해, 기하 위상 렌즈를 이용하여 전체 시스템의 크기를 줄이고, 시스템 오차를 보상하기 위한 파장 첨두 위치 추출 방법과 계통 오차 제거 방법을 설명한다. 색공초점 센서를 이용하여 투명한 물질의 두께를 측정하기 위한 이론을 설명하고, 이를 사파이어 및 BK7 물질의 두께를 측정함으로써 실험적으로 검증한다. 색공초점 센서를 이용한 두께 측정 방법은 기존의 간섭계 및 공초점 센서의 방법들에 비해 측정 속도가 빠르고, 분산 등에 의한 두께 측정 영역 제한이 없기 때문에 많은 응용이 가능하다.

• 한국광학회지
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• 제16권5호
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• pp.401-405
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• 2005

본 논문에서는 $250{\mu}m$ 직경의 황동선을 주기적으로 배열하여 기계적으로 형성한 장주기 광섬유 격자를 제안하였으며 전류제어로 파장가변 기능을 구현하였다. 광섬유 클래딩을 감싸고 있는 물질의 굴절률 변화가 공진파장의 함수임을 이용하여 클래딩 주위에 도포된 물질의 열 광학 계수가 금속선에 인가된 전력에 의해 제어되도록 함으로서 파장가변을 유도하였으며 주어진 파장 영역내에서 인가전력에 대한 공진파장의 가변 정도를 조사하였다. 글리세린의 열광학 효과를 이용한 경우 20 W 인가전력에 대하여 $LP_{03}$ 모드는 14nm, $LP_{04}$ 모드는 48 nm 정도의 파장가변이 가능함을 확인하였고, 단일모드 광섬유에 대한 기하 광학적 근사방법을 적용하여 해석한 결과와 잘 일치함을 보였다.