• 제목/요약/키워드: Optical damage

검색결과 366건 처리시간 0.025초

광섬유 센서를 이용한 섬유-금속 적층판의 손상 감지 (Damage Detection of Fiber-Metal Laminates Using Optical Fiber Sensors)

  • 양유창;한경섭
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2002년도 추계학술발표대회 논문집
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    • pp.161-164
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    • 2002
  • Optical fiber vibrations sensors (OFVSs) and extrinsic Fabry-Perot interferometer (EFPI) were used in damage monitoring of fiber-metal laminates(FML). The optical fiber vibration sensor and EFPI were applied in order to detect and evaluate the strain, damage and failure of FML. Damages in composites, such as matrix cracks, delamination and fiber breakage may occur as a result of excessive load, fatigue and low-velocity impacts. Tensile test was performed with the measurement of optical signal and acoustic emission (AE). The signals of the optical fiber vibration sensor due to damages were quantitatively evaluated by wavelet transform. EFPI was less sensible to the damage signals compared with the optical fiber vibration sensor. It was found that damage information of comparable in quality to acoustic emission data could be obtained from the optical fiber vibration sensor signals.

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섬유-금속 적층판의 인장 및 압입 하중에서의 손상감지 (Damage Detection of Fiber-Metal Laminates Under Axial and Indentation Load)

  • 양유창;한경섭
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.370-375
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    • 2003
  • Optical fiber vibrations sensors (OFVSs) and extrinsic Fabry-Perot interferometer (EFPI) were used in damage monitoring of fiber-metal laminates(FML). The optical fiber vibration sensor and EFPI were applied in order to detect and evaluate the strain, damage and failure of FML. Damages in composites, such as matrix cracks, delamination and fiber breakage may occur as a result of excessive load, fatigue and low-velocity impacts. Tensile and indentation test was performed with the measurement of optical signal and acoustic emission (AE). The signals of the optical fiber vibration sensor due to damages were quantitatively evaluated by wavelet transform. It was found that damage information of comparable in quality to acoustic emission data could be obtained from the optical fiber vibration sensor signals.

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섬유-금속 적층판의 압입 하중에서의 손상 및 파손 검출 (Damage and Failure Detection of Fiber-Metal Laminates Under Indentation Load)

  • 양유창;한경섭
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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    • pp.42-45
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    • 2003
  • Optical fiber vibrations sensors (OFVSs) and extrinsic Fabry-Perot interferometer (EFPI) were used in damage monitoring of fiber-metal laminates(FML). The optical fiber vibration sensor and EFPI were applied in order to detect and evaluate the strain, damage and failure of FML. Damages in composites, such as matrix cracks, delamination and fiber breakage may occur as a result of excessive load, fatigue and low-velocity impacts. Indentation test was performed with the measurement of optical signal and acoustic emission (AE). The signals of the optical fiber vibration sensor due to damages were quantitatively evaluated by wavelet transform. It was found that damage information of comparable in quality to acoustic emission data could be obtained from the optical fiber vibration sensor signals.

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레이저 트위저 라만 분광을 이용한 펨토초 광포획 동안의 적혈구 손상 분석 (Analysis of RBC Damage Using Laser Tweezers Raman Spectroscopy (LTRS) During Femtosecond Laser Optical Trapping)

  • 주성빈;표진우;장재영;이승덕;김법민
    • 한국광학회:학술대회논문집
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    • 한국광학회 2008년도 동계학술발표회 논문집
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    • pp.453-454
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    • 2008
  • femtosecond laser를 광원으로 하는 optical tweezers는 광포획 뿐만 아니라 비선형 현상을 발생시킬 수 있다는 장점을 가지고 있다. 그러나 높은 첨두 출력에 의하여 포획된 세포는 쉽게 손상되어 질 수 있다. 본 논문에서는 LTRS(Laser Tweezers Raman Spectroscopy)를 통하여 femtosecond laser와 CW laser에 의한 optical tweezers 상에서의 optical damage를 비교, 분석하였다.

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광강도형 광섬유 센서를 이용한 복합재 적충판의 피로손상 감시 (Monitoring of Fatigue Damage of Composite Laminates Using Embedded Intensity-Based Optical Fiber Sensors)

  • 이동춘;이정주;서대철
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2000년도 추계학술발표대회 논문집
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    • pp.124-127
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    • 2000
  • In this study, a technique for monitoring of fatigue damage of composite laminates by measuring the stiffness change using embedded intensity-based optical fiber sensors was investigated. Firstly, the underlying measurement principle and structure of intensity-based sensors and then a simple stiffness conversion process was explained. The monitoring technique was evaluated by fatigue tests of composite laminates with an embedded intensity-based sensor. From the test results, the response of the intensity-based sensor showed good correlation with that of surface mounted extensometer. Therefore, it can be concluded that the intensity-based sensors have good potential for the monitoring of fatigue damage of composite structures under fatigue loading. In addition, it could be confirmed that the intensity-based sensors have higher resistance to fatigue than the commercial electrical strain gauge.

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Study for Improvement of Laser Induced Damage of 1064 nm AR Coatings in Nanosecond Pulse

  • Jiao, Hongfei;Cheng, Xinbing;Lu, Jiangtao;Bao, Ganghua;Zhang, Jinlong;Ma, Bin;Liu, Huasong;Wang, Zhanshan
    • Journal of the Optical Society of Korea
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    • 제17권1호
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    • pp.1-4
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    • 2013
  • For the conventionally polished fused silica substrate, an around 100 nm depth redeposition polishing layer was formed on the top of surface. Polishing compounds, densely embedded in the redeposition polishing layer were the dominant factor that limited the laser induced damage threshold (LIDT) of transmission elements in nanosecond laser systems. Chemical etching, super-precise polishing and ion beam etching were employed in different ways to eliminate these absorbers from the substrate. After that, Antireflection (AR) coatings were deposited on these substrates in the same batch and then tested by 1064 nm nano-pulse laser. It was found that among these techniques only the ion beam etching method, which can effectively remove the polishing compound and did not induce extra absorbers during the disposal process, can successfully improve the LIDT of AR coatings.

Dynamic Characterization of Sub-Scaled Building-Model Using Novel Optical Fiber Accelerometer System

  • Kim, Dae-Hyun
    • 비파괴검사학회지
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    • 제31권6호
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    • pp.601-608
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    • 2011
  • This paper presents the damage assessment of a building structure by using a novel optical fiber accelerometer system. Especially, a sub-scaled building model is designed and manufactured to check up the feasibility of the optical fiber accelerometer for structural health monitoring. The novel accelerometer exploits the moir$\acute{e}$ fringe optical phenomenon and two pairs of optical fibers to measure the displacement with a high accuracy, and furthermore a pendulum to convert the displacement into acceleration. A prototype of optical fiber accelerometer system has been successfully developed that consists of a sensor head, a control unit and a signal processing unit. The building model is also designed as a 4-story building with a rectangular shape of $200{\times}300$ mm of edges. Each floor is connected to the next ones by 6 steel columns which are threaded rods. Basically, a random vibration test of the building model is done with a shaker and all of acceleration data is successfully measured at the assigned points by the optical fiber accelerometer. The experiments are repeated in the undamaged state and the damaged state. The comparison of dynamic parameters including the natural frequencies and the eigenvectors is successfully carried out. Finally, the optical fiber accelerometer is proven to be prospective to evaluate dynamic characteristics of a building structure for the damage assessment.

Gold-sapphire Plasmonic Nanostructures for Coherent Extreme-ultraviolet Pulse Generation

  • Han, Seunghwoi
    • Current Optics and Photonics
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    • 제6권6호
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    • pp.576-582
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    • 2022
  • Plasmonic high-order harmonic generation (HHG) is used in nanoscale optical applications because it can help in realizing a compact coherent ultrashort pulse generator on the nanoscale, using plasmonic field enhancement. The plasmonic amplification of nanostructures induces nonlinear optical phenomena such as second-order harmonic generation, third-order harmonic generation, frequency mixing, and HHG. This amplification also causes damage to the structure itself. In this study, the plasmonic amplification according to the design of a metal-coated sapphire conical structure is theoretically calculated, and we analyze the effects of this optical amplification on HHG and damage to the sample.

CZ법으로 성장시킨 $LiNbO_3$: Mg 단결정에서의 광손상에 관한 연구 (A study on the optical damage in $LiNbO_3$: Mg single crystals grown by CZ method)

  • 노지현;김비오;김병국;윤종규
    • 한국결정성장학회지
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    • 제5권1호
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    • pp.1-10
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    • 1995
  • CZ법을 이용하여 합치용융조성(congruent) $LiNbO_3$ 및 광손상에 큰 저항성을 보이는 $LiNbO_3$ : Mg 단결정에 MgO 첨가량을 2, 5 및 7 mol%로 변화시키면서 육성하여, 보상 방법으로 광손상을 측정하였다. 5 mol% 이상의 MgO 첨가시 광흡수단 및 $OH^-$ 흡수밴드의 특성이 크게 변화함을 관찰함으로써 MgO 첨가량에 일정한 역치(threshold)가 존재함을 확인하였다. $LiNbO_3$ : Mg 단결정에서는 5 mol% 이상의 MgO 첨가시 Mg가 Nb 자리를 차지하여$Mg_{Nb}^{2+}$를 형성함에 따라 광손상에 대한 저항이 크게 향상될 수 있다. 실제로 융액에 5 mol% 이상의 MgO 첨가시)$LiNbO_3$ : Mg 단결정의 광손상 저항이 3배 이상 향상되었다.

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기계적 손상에 의한 실리콘 웨이퍼의 반송자 수명과 표면 거칠기와의 관계 (Relationships between Carrier Lifetime and Surface Roughness in Silicon Wafer by Mechanical Damage)

  • 최치영;조상희
    • 한국전기전자재료학회논문지
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    • 제12권1호
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    • pp.27-34
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    • 1999
  • We investigated the effect of mechanical back side damage in viewpoint of electrical and surface morphological characteristics in Czochralski silicon wafer. The intensity of mechanical damage was evaluated by minority carrier recombination lifetime by laser excitation/microwave reflection photoconductance decay technique, atomic force microscope, optical microscope, wet oxidation/preferential etching methods. The data indicate that the higher the mechanical damage degree, the lower the minority carrier lifetime, and surface roughness, damage depth and density of oxidation induced stacking fault increased proportionally.

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