• Title, Summary, Keyword: Laser Scattering

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Study on Analysis of Optical Deflection of Laser Scattering Based on Rayleigh Criterion for Crystalline Silicon Wafer in Solar Cell (태양전지용 결정질 실리콘 웨이퍼에서의 레일리기준 기반 레이저산란의 광편향 분석에 관한 연구)

  • Kim, Gyung-Bum
    • Journal of the Semiconductor & Display Technology
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    • v.9 no.4
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    • pp.31-37
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    • 2010
  • In this paper, optical deflection of laser scattering has been investigated based on Rayleigh criterion for crystalline silicon wafer in solar cell. A laser scattering mechanism is newly designed using light scattering properties in silicon wafer. Intensity distributions of laser scattering are different, depending on the incident angle of laser computed from Rayleigh criterion. In case of the incident angle satisfied with the criterion, they are asymmetric. Also, their specular reflection angle is shifted to unpredicted ones. These phenomena are in accordance with previous theories of laser scattering. The optical deflection of laser scattering is experimentally identified with the designed laser scattering mechanism. Its mathematical model is presented from the geometric relationship of laser scattering. It is shown that the optical deflection of laser scattering agree with the presented model, exclusive of grazing angles which is satisfied with Rayleigh criterion.

Investigation of Laser Scattering Pattern and Defect Detection Based on Rayleigh Criterion for Crystalline Silicon Wafer Used in Solar Cell (태양전지 실리콘 웨이퍼에서의 레일리기준 기반 레이저산란 패턴 분석 및 결함 검출)

  • Yean, Jeong-Seung;Kim, Gyung-Bum
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.5
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    • pp.606-613
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    • 2011
  • In this paper, patterns of laser scattering and detection of micro defects have been investigated based on Rayleigh criterion for silicon wafer in solar cell. Also, a new laser scattering mechanism is designed using characteristics of light scattering against silicon wafer surfaces. Its parameters are to be optimally selected to obtain effective and featured patterns of laser scattering. The optimal parametric ranges of laser scattering are determined using the mean intensity of laser scattering. Scattering patterns of micro defects are investigated at the extracted parameter region. Among a lot of pattern features, both maximum connected area and number of connected component in patterns of laser scattering are regarded as the important information for detecting micro defects. Their usefulness is verified in the experiment.

A Study on the Optimal Condition Determination of Laser Scattering Using the Design of Experiment (실험계획법을 이용한 레이저 산란의 최적 조건 결정에 대한 연구)

  • Han, Jae-Chul;Kim, Gyung-Bum
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.7
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    • pp.58-64
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    • 2009
  • In this paper, an inspection mechanism based on laser scattering has been developed for the surface evaluation of infrared cut-off filters, and optimum conditions of laser scattering are determined using the design of experiment. First of all, attributes and influence factors of laser scattering are investigated and then a laser scattering inspection mechanism is newly designed based on analyses of laser scattering parameters. Also, Taguchi method, one of experimental designs, is used for the optimum condition selection of laser scattering parameters and the optimum condition is determined in order to maximize the detection capability of surface defects. Experiments show that the proposed method is useful in a consistent and effective defect detection and can be applied to surface evaluation processes in manufacturing.

Study on Experimental Selection of Parameters in Laser Scattering Mechanism and Analysis of Laser Scattering Patterns in Solar Cell Wafer (레이저 산란 메커니즘 매개변수의 실험적 선정 및 태양전지 웨이퍼의 레이저산란패턴 분석에 관한 연구)

  • Kim, Gyung-Bum
    • Journal of the Semiconductor & Display Technology
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    • v.10 no.2
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    • pp.7-12
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    • 2011
  • In this paper, a laser scattering mechanism are designed to detect micro defects such as dent, scratch, pinhole, etc. Its influential parameters are experimentally selected and scattering patterns of micro defects have been analyzed for silicon wafer in solar cell. As a result of experiments, scattered lights are rather increased in wafer surface with micro defects, in comparison to no micro ones. Scattering parameters are optimally selected for obtaining robust and high quality laser scattering images of micro defects. It is shown that scattered light components are linearly increased according to the increase of micro defect sizes, and the depth of micro-defects give a large influence on optical deflection.

Scattering analysis of laser beam drilling in porous ceramic materials (극초단 레이저를 이용한 기공성 세라믹 드릴링시 발생하는 레이저빔 산란해석)

  • Choi, Hae Woon
    • Laser Solutions
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    • v.15 no.4
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    • pp.6-11
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    • 2012
  • Laser beam can be either absorbed or scattered in porous ceramic material and its optical characteristics need to be understood. Electro-magnetic multiphysics software was used to simulate and understand the actual scattering phenomena in porous materials. 785nm femtosecond laser was irradiated on the surface of ceramic material and strong scattering occurred in drilling process. The computer results showed the scattering and absorption phenomena of Aluminum oxide were a mixture of dielectric and metallic material. The computer simulation showed the laser beam was almost extinct at the aspect rate of 5 approximately.

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Dynamic Quasi-Elastic Light Scattering Measurement of Biological Tissue

  • Youn, Jong-In;Lim, Do-Hyung
    • Journal of Biomedical Engineering Research
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    • v.28 no.2
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    • pp.169-173
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    • 2007
  • During laser irradiation, mechanically deformed cartilage undergoes a temperature dependent phase transformation resulting in accelerated stress relaxation. Clinically, laser-assisted cartilage reshaping may be used to recreate the underlying cartilaginous framework in structures such as ear, larynx, trachea, and nose. Therefore, research and identification of the biophysical transformations in cartilage accompanying laser heating are valuable to identify critical laser dosimetry and phase transformation of cartilage for many clinical applications. quasi-elastic light scattering was investigated using Ho : YAG laser $(\lambda=2.12{\mu}m\;;\;t_p\sim450{\mu}s)$ and Nd:YAG Laser $(\lambda=1.32{\mu}m\;;\;t_p\sim700{\mu}s)$ for heating sources and He : Ne $(\lambda=632.8nm)$ laser, high-power diode pumped laser $(\lambda=532nm)$, and Ti : $Al_2O_3$ femtosecond laser $(\lambda=850nm)$ for light scattering sources. A spectrometer and infrared radiometric sensor were used to monitor the backscattered light spectrum and transient temperature changes from cartilage following laser irradiation. Analysis of the optical, thermal, and quasi-elastic light scattering properties may indicate internal dynamics of proteoglycan movement within the cartilage framework during laser irradiation.

Study on the Experimental Identification of Surface Roughness Using Laser Scattering Image (레이저 산란 영상을 이용한 표면거칠기의 실험적 규명에 관한 연구)

  • Hong, Yeon-Ki;Kim, Gyung-Bum
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.1
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    • pp.35-41
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    • 2010
  • In this paper, surface roughness has been experimentally identified using laser scattering images. The parameters and optical deflected rays of laser scattering are investigated on laser scattering system, and then their optimum parameters on grinding surfaces are selected using design of experiment. The application of the optimum parameters results in featured laser scattering images, in which the mean of vertical scattering distributions is regarded as a feature. It is shown that the feature of laser scattering distributions is linearly increased according to grinding surface roughness and so the information can be used as important factor for the measurement and evaluation of various surface roughness. In the future, the performance of the proposed laser scattering method will be evaluated using AFM.

An Experimental Analysis on Dark-field Laser Scattering for the Surface Inspection of Infrared Cut-off Filters (적외선차단필터의 표면 검사를 위한 암시야 레이저산란에 대한 실험적 분석)

  • Kim, Gyung-Bum;Han, Jae-Chul
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.11
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    • pp.76-83
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    • 2007
  • The dark-field laser scattering system has been developed to inspect surface defects in infrared cut-off filters and then laser scattering characteristics against the defects are investigated. The qualitative analysis for the reliable and accurate detection performance is described through the correlation between incident angles of a laser and viewing ones of a camera. In this paper, reliable and important information with laser scattering is given for the surface defect inspection of IR filters. Its performance has been verified through various experiments.

Study on Experimental Modeling and Estimation of Roughness of Nanoscale Lapping Surface Based on Laser Scattering Patterns (레이저산란패턴 기반 나노 래핑 표면 거칠기의 실험적 모델링 및 추정에 관한 연구)

  • Hong, Yeon-Ki;Kim, Gyung-Bum
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.1
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    • pp.107-114
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    • 2011
  • In this study, a correlation between the roughness of nanoscale lapping surface and its laser scattering pattern has been identified experimentally. The characteristics of laser scattering on a reflected surface are investigated, and a laser scattering mechanism is newly designed by adopting the dark-field method. Laser scattering patterns resulting from nanoscale lapping shape are in the shape of crossed irregular lattice. In addition, optimum laser scattering images are obtained by the design of experiment, and the roughness of nanoscale lapping surface is estimated using regression analysis certain useful features of the laser scattering patterns. The results of fifty experiments on three types of nanoscale lapping surfaces show that the roughness of nanoscale lapping surfaces can be accurately estimated by the proposed mathematical modeling method.

Penetration depth and Wave Propagation in Random Media (무질서한 매질에서 침투깊이와 파동 전파)

  • Kim, Ki-Jun;Sung, Ki-Chun
    • Journal of the Korean Applied Science and Technology
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    • v.23 no.1
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    • pp.70-76
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    • 2006
  • The influence of fluorophor, scatterer, absorber in turbid materials by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it is studied the molecular property by laser induced fluorescence spectroscopy. It can be found that the effects of optical property are penentrated in scattering media by the optical $parameters({\mu}s$, ${\mu}a$, ${\mu}t$, ${\gamma}$, ${\rho})$. The value of scattering coefficient ${\mu}s$ is large appeared by means of the increasing particles of scattering, it can be found that the slope appears exponentially as a function of distance from laser source to detector. It may also utilize in designing the best model for oil chemistry, laser medicine and application of medical engineering.