• Title/Summary/Keyword: 배열 광센서

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A Study on the Liquid-level Sensors Using Splitting Ratio of Fiber-optic Directional Couplers (광섬유형 방향성 결합기의 광 분배비를 이용한 수위 센서 연구)

  • Sohn, Kyung-Rak;Key, Kwang-Hyun
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.6
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    • pp.846-851
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    • 2010
  • A liquid-air interface sensing system using the flat end surfaces of a fused-silica fiber coupler has been demonstrated. The principle is based on the additional optical loss caused by changing the refractive index of the external material at the boundary of the end face made of a fiber. The immersion characteristics of this system with respect to the different splitting ratios of the couplers were investigated to determine the sensitivity when it responses to water and air. These experimental data are very useful for selecting the coupling ratio of a coupler in order to develop a multiple sensing probe system. In the proposed sensor structure, it can be emphasize that the sensing probe can be appropriately arrayed on the basis of splitting ratio of the coupler. As a result, it is expected that the proposed liquid-air interface sensors can also be applied to monitor flooding that occurs in multiple areas at the same time.

Synthesis and Application of Hybrid Nanostructure Containing Quantum Dots

  • U, Gyeong-Ja;Yu, Hye-In;Jang, Ho-Seong;Kim, Sang-Gyeong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.131-131
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    • 2014
  • 양자점은 전통적인 유기 염료에 비해 흡광영역이 넓고 발광 피크의 폭이 좁으며, 흡광과 발광 사이의 에너지 차가 커서 검출이 용이하고, 광안정성이 우수할 뿐만 아니라, 단순히 크기를 조절함으로써 발광 피크의 에너지를 제어할 수 있는 특장 때문에 많은 연구가 진행되었다. 그러나 많은 나노입자들과 마찬가지로 실질적인 응용을 위해서는 양자점 나노입자들도 대부분 표면개질을 거쳐야 하는데, 이 과정이 까다롭고 또 표면개질 중에 나노입자들의 응집이 일어나거나 광특성이 나빠지는 등의 문제가 흔히 발생한다. 한편, 서브미크론 크기의 입자들은 나노입자에 비해 응집현상이 미미해서 상대적으로 취급이 용이하다. 그 중에서도 실리카 입자들은 합성방법도 쉽게 확립되어 있고 생체친화성이 우수하며 그 표면화학 반응이 이미 잘 알려져 있어서 활용하기가 매우 용이하다. 따라서 양자점 층을 실리카 표면 가까이에 자기조립을 통해 배열한 하이브리드 구조는 양자점의 장점을 편리하게 이용할 뿐만 아니라 실리카의 표면개질 특성도 그대로 이용할 수 있다는 이중의 장점이 있다. 본 논문에서는 코어/쉘 구조로 안정화된 II-VI 반도체 양자점 층을 아래 그림 1과 같이 실리카 콜로이드 내에 배열한 하이브리드 구조를 소개하고, 이 하이브리드 구조를 표면개질 하여 LED 칩 위에 패키징 함으로써 백색광을 제조한 연구 및 더 나아가 중심에 초상자성 클러스터 핵을 배치하고 이를 둘러싼 실리카 콜로이드 표면 가까이에 양자점 층을 배열한 초상자성 하이브리드 구조를 합성하여 이를 on-site sensor에 적용한 연구 결과를 소개한다.

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Multiplexed Bend Loss Type Single-Mode Fiber-Optic Displacement Sensor Using Reflection Signals Generated at Optical Connectors (광커넥터의 반사를 이용한 다중화된 굽힘 손실형 단일모드 광섬유 변위센서)

  • Yoo Jung-Ae;Jo Jae Heung;Kwon Il-Bum
    • Korean Journal of Optics and Photonics
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    • v.15 no.5
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    • pp.415-422
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    • 2004
  • We propose and present a new multiplexed bend loss type single-mode fiber-optic sensor system for displacement measurement in order to measure the displacement of several mm of civil engineering structures such as bridges and buildings. We make a bend loss type fiber-optic sensor for measuring displacements using the signal difference between two reflection signals due to various bend losses generating at a pair of optical connectors by using the optical time domain reflectometer. And we fabricate a multiplexed bend loss type fiber-optic sensor detecting linear displacements of 4 measuring positions of an object by setting these new 4 fiber-optic sensors on a single mode fiber simultaneously. We find that the multiplexed fiber-optics displacement sensor has linearity of 0.9942, maximum displacement of 6 mm, and accuracy of 6% for 4 measuring points.

Optimization of Light Guide Thickness for Optimal Flood Image Acquisition of a 14 × 14 Scintillation Pixel Array (14 × 14 섬광 픽셀 배열의 최적의 평면 영상 획득을 위한 광가이드 두께 최적화)

  • Lee, Seung-Jae
    • Journal of the Korean Society of Radiology
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    • v.16 no.4
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    • pp.365-371
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    • 2022
  • In order to obtain excellent spatial resolution in the PET detector, when the detector module is designed using very small scintillation pixels, overlap occurs at the edges and corners of the scintillation pixel array in the flood image. By using a light guide, the occurrence of overlap can be reduced. In this study, after using a scintillator of 0.8 mm × 0.8 mm × 20 mm to form a 14 × 14 array, 3 mm × 3 mm SiPM pixels are combined with 4 × 4 photosensor to reduce the occurrence of overlap. The optimal thickness of the light guide used for this purpose was derived. Quantitative evaluation was performed based on scintillation pixel images of edges and corners where overlap occurs mainly in the acquired flood image. Quantitative evaluation was calculated through the interval and full width at half maximum between scintillation pixel images, and when a light guide with a thickness of 2 mm was used, the best image was obtained with a k value of 2.60. In addition, as a result of measuring the energy resolution through the energy spectrum, the light guide with a thickness of 2 mm showed the best result at 28.5%. If a 2 mm light guide is used, it is considered that the best flood image and energy resolution with minimal overlap can be obtained.

Digital Position Measurement with MLPE of PET detector using a Small Number of Photosensors (적은 수의 광센서를 사용한 PET 검출기의 최대우도함수를 적용한 디지털 위치 측정)

  • Kang, Seunghun;Lee, Seung-Jae
    • Journal of the Korean Society of Radiology
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    • v.16 no.2
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    • pp.151-156
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    • 2022
  • A detector using a small number of photosensors was designed, and the position of a scintillation pixel that interacted with gamma rays through a maximum likelihood position estimation(MLPE) was measured as a digital position. For this purpose, simulation was performed using DETECT2000, which can simulate the movement of light within the scintillator, and the accuracy of position measurement was evaluated. A detector was configured using a 6 × 6 scintillation pixel array and 4 photosensors, and a gamma ray event was generated at the center of each scintillation pixel to create a look-up table through the ratio of acquired light. The gamma-ray event generated at the new position was applied as the input value of the MLPE, and the positiion of the scintillation pixel was converted into a digital positiion after comparison with the look-up table. All scintillation pixels were evaluated, and as a result, a high accuracy of 99.1% was obtained. When this method is applied to the currently usesd system, it is concidered that the process of determining the position of the scintillation pixel will be simplified.

A Mechanism Study of a HyperSpectral Image Sensor for Nadir and Slant Range Operation (직하방과 빗각 촬영 운용을 위한 초분광 영상센서 구동방식에 관한 연구)

  • Lee, Kyeongyeon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.22 no.4
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    • pp.484-491
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    • 2019
  • General Hyperspectral Image Sensor acquires an image of line form such as a thin rectangle shape because of using 1D array Push Broom or Whisk Broom scanning method. A special mechanism is required for a Hyperspectral Image Sensor to operate for nadir and slant range. To design the mechanism, the characteristics of the flight motion and the overlap rate between consecutive frames were analyzed. Also, system requirements were proposed through modeling and simulation.

Mechanically Induced Long Period Fiber Grating Array Device and Sensor Application (기계적으로 유도되는 장주기 광섬유 격자 배열 소자 및 센서 응용)

  • Lee, Nam-Kwon;Song, Jae-Won;Park, Jea-Hee
    • Korean Journal of Optics and Photonics
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    • v.18 no.2
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    • pp.142-148
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    • 2007
  • A mechanically induced long-period fiber grating array was fabricated and its transmission characteristics were measured. The grating away consisted of a rubber cover and a 45 cm metal bar with 10 grating groups. Each grating group was composed of 60 gratings. The period of the grating of the grating groups was increased by $10{\mu}m$ increments from $690{\mu}m$ to $780{\mu}m$. The long period fiber grating was induced when the pressure was applied on the long period grating array and the resonant wavelength depended on the position of applied pressure. The experimental results shows that this long period fiber grating away can be used as a various band rejection filter or a fiber optic sensor.

A Probe of Fiber Optic OTDR Displacement Sensor (광섬유 OTDR변위 센서의 탐촉자)

  • Kwon, Il-Bum;Kim, Chi-Yeop;Seo, Dae-Cheol
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.5
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    • pp.350-355
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    • 2005
  • The probes of fiber optic OTDR (Optical Time Domain Reflectometry) sensor was developed to measure displacements of social infrastructures. This probe was simply constructed with two conventional optical fiber connectors, and a fiber bending part, which transforms displacement to optical loss. When the displacement was affected on the bending loss part, the reflected light intensity of one optical connector was changed. The displacement was determined from this reflected light intensity change of the connector. fiber optic OTDR displacement sensor was developed as the multiplexed type of one fiber line with 5 sensor probes. Multiplexing operation was tested by these 5 sensor probes.

Fabrication of flexible, thin-film photodetector arrays

  • Park, Hyeon-Gi;Lee, Gil-Ju;Song, Yeong-Min
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.269-269
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    • 2016
  • 최근, 플렉서블 광전자소자 제작 기술의 눈부신 발전으로, 기존의 평면형 이미지 센서가 가지고 있는 여러가지 한계를 극복하기 위해 곡면형 이미지 센서 제작에 대한 다양한 연구가 진행되고 있다. 리소그래피, 물질 성장, 도포, 에칭 등의 대부분의 반도체 공정은 평면 기판에 기반한 공정 방법으로 곡면 구조의 이미지 센서를 제작하기에는 많은 어려움이 있다. 본 연구에서는 곡면형 이미지 센서의 제작을 위해 곡면 구조 위에서의 직접적인 공정 대신 평면 기판에서 단결정 실리콘을 이용해 전사 인쇄가 가능하고 수축이 가능한 초박막 구조의 이미지 센서를 제작한 후 이를 떼어내는 방식을 이용하였다. 이온 주입 및 건식 식각 공정을 통해 평면 SOI (Silicon on Insulator) 기판 위에 단일 광다이오드 배열 형태의 소자를 제작한 후 수 차례의 폴리이미드 층 도포 및 스퍼터링을 통한 금속 배선 공정을 통해 초박막 형태의 광 검출기를 완성한다. 이후 습식 식각 및 폴리디메틸실록산(PDMS) 스탬프를 이용한 전사 인쇄 공정을 통해 기판으로부터 디바이스를 분리하여 변형 가능한 형태의 이미지 센서를 얻을 수 있다. 이러한 박막형 이미지 센서는 유연한 재질로 인해 수축 및 팽창, 구부림과 같은 구조적 변형이 가능하게 되어 겹눈 구조 카메라, 튜너블 카메라 등과 같이 기존 방식의 반도체 공정으로는 구현할 수 없었던 다양한 이미징 시스템 개발에 적용될 수 있을 것으로 기대된다.

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DOI Detector Design using Different Sized Scintillators in Each Layer (각 층의 서로 다른 크기의 섬광체를 사용한 반응 깊이 측정 검출기 설계)

  • Seung-Jae, Lee
    • Journal of the Korean Society of Radiology
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    • v.17 no.1
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    • pp.11-16
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    • 2023
  • In preclinical positron emisson tomography(PET), spatial resolution degradation occurs outside the field of view(FOV). To solve this problem, a depth of interaction(DOI) detector was developed that measures the position where gamma rays and the scintillator interact. There are a method in which a scintillation pixel array is composed of multiple layers, a method in which photosensors are arranged at both ends of a single layer, a method in which a scintillation pixel array is constituted in several layers and a photosensor is arranged in each layer. In this study, a new type of DOI detector was designed by analyzing the characteristics of the previously developed detectors. In the two-layer detector, different sizes of scintillation pixels were used for each layer, and the array size was configured differently. When configured in this form, the positions of the scintillation pixels for each layer are arranged to be shifted from each other, so that they are imaged at different positions in a flood image. DETECT2000 simulation was performed to confirm the possibility of measuring the depth of interaction of the designed detector. A flood image was reconstructed from a light signal acquired by a gamma-ray event generated at the center of each scintillation pixel. As a result, it was confirmed that all scintillation pixels for each layer were separated from the reconstructed flood image and imaged to measure the interaction depth. When this detector is applied to preclinical PET, it is considered that excellent images can be obtained by improving spatial resolution.