• Title/Summary/Keyword: Laser-Induced Fluorescent

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An Experimental Investigation of Air Fuel Ratio Measurement using Laser Induced Acetone Fluorescence (아세톤 형광을 이용한 공연비 측정 기법 연구)

  • Park Seungjae;Huh Hwanil;Oh Seungmook
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.353-356
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    • 2002
  • Planar laser induced fluorescence(PLIF) has been widely used to obtain two dimensional fuel distribution. Preliminary investigation was performed to measure quantitative air excess ratio distribution in an engine fueled with LPG. It is known that fluorescence signal from acetone as a fluorescent tracer is less sensitive to oxygen quenching than other dopants. Acetone was excited by KrF excimer laser (248nm) and its fluorescence image was acquired by ICCD camera with a cut-of filter to suppress Mie scattering from the laser light. For the purpose of quantifying PLIF signal, an image processing method including the correction of laser sheet beam profile was suggested. Raw images were divided by each intensity of laser energy and profile of laser sheet beam. Inhomogeneous fluorescence images scaled with the reference data, which was taken by a calibration process, were converted to air excess ratio distribution. This investigation showed instantaneous quantitative measurement of planar air excess ratio distribution for gaseous fuel.

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Laser Diagnostics of Spray and Combustion Characteristics Using Multi-Component Mixed Fuels in a D.I. Diesel Engine (다성분 혼합연료를 이용한 디젤 분무 및 연소특성의 광계측 진단)

  • Yoon, Jun-Kyu;Myong, Kwang-Jae;Senda, Jiro;Fujimoto, Hajime;Cha, Kyung-Ok
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.5
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    • pp.172-180
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    • 2006
  • This study was to analyze the effect of mixed fuel composition and mass fraction on the characteristics of evaporating diesel spray and combustion under the various ambient conditions. The characteristics of vaporization distribution and combustion were visualized by laser induced fluorescent method and direct photography. The experiments were conducted in the constant volume vessel and rapid compression expansion machine with optical access. Multi-component fuels mixed i-octane, n-dodecane and n-hexadecane were injected the vessel and rapid compression expansion machine with electronically controlled common rail injector. Experimental results show that fuel vapor formed stratified distribution. And vaporization and diffusion are become actively increasing in mass fraction of low boiling point component. Consequently multi-component fuels were expected to control the evaporating behavior according to their suitable mass fraction.

Micro-LIF measurement of microchannel flow

  • Kim Kyung Chun;Yoon Sang Youl
    • 한국가시화정보학회:학술대회논문집
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    • 2004.12a
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    • pp.65-74
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    • 2004
  • Measurement of concentration distributions of suspended particles in a micro-channel is out of the most crucial necessities in the area of Lab-on-a-chip to be used for various bio-chemical applications. One most feasible way to measure the concentration field in the micro-channel is using micro-LIF(Laser Induced Fluorescence) method. However, an accurate concentration field at a given cross plane in a micro-channel has not been successfully achieved so far due to various limitations in the light illumination and fluorescence signal detection. The present study demonstrates a novel method to provide an ultra thin laser sheet beam having five(5) microns thickness by use of a micro focus laser line generator. The laser sheet beam illuminates an exact plane of concentration measurement field to increase the signal to noise ratio and considerably reduce the depth uncertainty. Nile Blue A was used as fluorescent dye for the present LIF measurement. The enhancement of the fluorescent intensity signals was performed by a solvent mixture of water $(95\%)$ and ethanol (EtOH)/methanol (MeOH) $(5\%)$ mixture. To reduce the rms errors resulted from the CCD electronic noise and other sources, an expansion of grid size was attempted from $1\times1\;to\;3\times3\;or\;5\times5$ pixel data windows and the pertinent signal-to-noise level has been noticeably increased accordingly.

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Application of Micro-Thin Laser sheet and Mixed Solvent for Micro-LIF Measurement in a Microchannel (마이크로 채널 내부의 Micro-LIF 측정을 위한 마이크로 레이저 평면빔과 혼합용매의 적용)

  • Yoon Sang Youl;Kim Jae Min;Kim Kyung Chun
    • 한국가시화정보학회:학술대회논문집
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    • 2004.11a
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    • pp.86-89
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    • 2004
  • One most feasible way to measure the concentration field in the micro-channel is using micro-LIF(Laser Induced Fluorescence) method. However, an accurate concentration field at a given cross plane in a micro-channel has not been successfully achieved so far due to various limitations in the light illumination and fluorescence signal detection. The present study demonstrates a novel method to provide an ultra thin laser sheet beam having five(5) microns thickness by use of a micro focus laser line generator. The laser sheet beam illuminates an exact plane of concentration measurement field to increase the signal to noise ratio and considerably reduce the depth uncertainty. Nile Blue A was used as fluorescent dye for the present LIF measurement. The enhancement of the fluorescent intensity signals was performed by a solvent mixture of water $(95\%)$ and ethanol (EtOH)/methanol (MeOH) $(5\%)$ mixture. To reduce the rms errors resulted from the CCD electronic noise and other sources, an expansion of grid size was attempted from $1\times1$ to 3(3 or 5(5 pixel data windows and the pertinent signal-to-noise level has been noticeably increased accordingly.

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The optical analysis of discharge lamp by Laser

  • Yang, Jong-Kyung;Lee, Jong-Chan;Choi, Yong-Sung;Park, Dae-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.570-571
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    • 2005
  • In this paper, we introduced a LIF measurement method and summarized the theoretical side. When an altered wavelength of laser and electric power, lamp applied electric power, we measured the relative density of the metastable state in mercury after observing a laser induced fluorescence signal of 404.8nm and 546.2nm, and confirmed the horizontal distribution of plasma density in the discharge lamp. The results confirmed the resonance phenomenon regarding the energy level of atoms along a wavelength change, and also confirmed that the largest fluorescent signal in 436nm, and that the density of atoms in 546.2nm ($6^3S_1\rightarrow6^3P_2$) were larger than 404.8nm ($6^3S_1\rightarrow6^3P_1$). According to the increase of lamp applied electric power, plasma density increased, too. When increased with laser electric power, the L1F signal reached a saturation state in more than 2.6mJ. When partial plasma density distribution along a horizontal axis was measured using the laser induced fluorescence method, the density decreased by recombination away from the center.

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Evaluation of Plasma Characteristics for Hg-Ar Using LIF (LIF를 이용한 Hg-Ar 플라즈마 특성 평가)

  • Moon, Jong-Dae
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.2
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    • pp.79-83
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    • 2008
  • In this paper, we introduced a LIF measurement method and summarized the theoretical side. When an altered wavelength of laser and electric power, lamp applied electric power, we measured the relative density of the metastable state in mercury after observing a laser induced fluorescence signal of 404.8nm and 546.2nm, and confirmed the horizontal distribution of plasma density in the discharge lamp. Due to this generation, the extinction of atoms in a metastable state occurred through collision, ionization, and excitation between plasma particles. The density and distribution of the metastable state depended on the energy and density of plasma particles, intensely. This highlights the importance of measuring density distribution in plasma electric discharge mechanism study. The results confirmed the resonance phenomenon regarding the energy level of atoms along a wavelength. change, and also confirmed that the largest fluorescent signal in 436nm, and that the density of atoms in 546.2nm ($6^3S_1{\to}6^3P_2$) were larger than 404.8nm ($6^3S_1{\to}6^3P_2$). According to the increase of lamp applied electric power, plasma density increased, too. When increased with laser electric power, the LIF signal reached a saturation state in more than 2.6mJ. When partial plasma density distribution along a horizontal axis was measured using the laser induced fluorescence method, the density decreased by recombination away from the center.

Visualization of Breakup and Atomization Processes in Non-evaporating Diesel Sprays (비증발 디젤분무의 분열과 미립화 과정의 가시화)

  • 원영호;김우태
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.1
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    • pp.25-31
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    • 2004
  • Two-dimensional laser visualization methods have been used in the study of breakup and atomization processes of non-evaporating diesel sprays. A single-hole spray injected into a quiescent atmospheric environment was visualized by the LIF(Laser Induced Fluorescence) and scattering technique. The LIF technique could be implemented to take the images which are magnified enough to show the shape of liquid ligaments and small droplets. The spontaneous scattering and fluorescent images of sprays were also taken to investigate the atomization of droplets. In the tip and periphery of a spray. the scattering light is bright and the ratio of fluorescent/scattering intensity is lower. This characteristics indicate the very high number density of small droplets which are well atomized.

Acetone PLIF for Fuel Distribution Measurements in Liquid Phase LPG Injection Engine (LPG 액상분사 엔진에서 아세톤 PLIF를 이용한 연료분포 측정기법 연구)

  • 오승묵;박승재;허환일;강건용;배충식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.1
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    • pp.74-82
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    • 2004
  • Planar laser-induced fluorescence(PLIF) has been widely used to obtain two dimensional fuel distribution. Acetone PLIF is chosen because fluorescence signal from acetone as a fluorescent tracer is less sensitive to oxygen quenching than other dopants. Acetone PLIF is applied to measure quantitative air excess ratio distribution in an engine fueled with LPG. Acetone is excited by KrF excimer laser (248nm) and its fluorescence image is acquired by ICCD camera with a cut-off filter to suppress Mie scattering from the laser light. For the purpose of quantifying PLIF signal, an image processing method including the correction of laser sheet beam profile is suggested. Raw images are divided by each intensity of laser energy and profile of laser sheet beam. Inhomogeneous fluorescence images scaled with the reference data, which is taken by a calibration process, are converted to air excess ratio distribution. This investigation shows instantaneous quantitative measurement of planar air excess ratio distribution for gaseous fuel.

Micro-LIF Measurement in a Micro-channel Using an Micro Laser Light Sheet (마이크로 레이저 평면빔을 이용한 마이크로채널 내에서의 Micro-LIF 측정)

  • Yoon, Sang-Youl;Kim, Jae-Min;Kim, Su-Hun;Kim, Kyung-Chun
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1540-1545
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    • 2004
  • Measurement of concentration fields in a micro-channel is the crucial technology in the area of Lab-on-a-chip to be used for various bio-chemical applications. It is wel-known that the only possible way to measure the concentration field in the micro-channel is using micro-LIF(Laser Induced Fluorescence) method. However, an accurate concentration field at a given cross plane in a micro-channel has not been made so far due to the limit of light illumination. The present study demonstrates a novel method to provide an ultra thin laser sheet beam having 5 microns thickness by a micro focus laser line generator. Nile Blue A was used as fluorescent dye for LIF measurement. The laser sheet beam illuminates an exact plane of concentration measurement in the micro-channel to increase the signal to noise ratio and reduce the depth uncertainty considerably.

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A STUDY ON THE CARIES ACTIVITY TEST WITH VISIBLE LIGHT INDUCED BY LASER (가시 레이저 광을 이용한 치아우식활성검사에 관한 연구)

  • Lee, Sang-Ho;Lee, Nang-Young
    • Journal of the korean academy of Pediatric Dentistry
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    • v.27 no.1
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    • pp.161-168
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    • 2000
  • The purpose of this study was to develop a practical caries activity test using laser fluorescence. The subjects of study were 30 children of $7\sim10$ years old. Fluorescence from initial carious lesion of teeth illuminated by an argon laser(488nm) was observed through barrier alter. For evaluation of accuracy and propriety of this method fer caries activity test, teeth with initial caries lesion on buccal or labial surface of children was examined with visual inspection and laser fluorescence. Visual examination for the dDfFtT and the $Cariescreen^{(R)}$ test were also done. The results from the present study can be summarized as follows: 1. Laser fluorescence test could differentiate initial caries lesions more easily than visiual inspection. 3. There was highest correlation(= 0.73) between laser fluorescent test and $Cariescreen^{(R)}$ test and. And also apparent correlation(= 0.66) exists between laser fluorescent test and caries experience measured by dDfFtT.

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