• 한국정밀공학회지
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• 제26권7호
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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.

• 반도체디스플레이기술학회지
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• 제9권4호
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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.

• 반도체디스플레이기술학회지
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• 제10권2호
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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.

• 한국정밀공학회지
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• 제28권5호
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.501-502
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• 2008

• 한국가시화정보학회지
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• 제2권1호
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• pp.52-56
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• 2004

Several visualization techniques of laser diagnostics are presented for combustion phenomena, including Mie scattering for flow, Rayleigh and Raman scattering spectroscopy for major species, laser-induced fluorescence for minor species, and laser-induced incandescence for soot. These techniques have been applied to understand the various combustion phenomena more clearly, including buoyancy-dominant flow system, diffusion flam oscillation, laminar and turbulent lifted flames, flame propagation along a vortex ring, and soot zone characteristics. The usefulness of laser diagnostics on a better understanding of physical mechanism is demonstrated.

• 대한기계학회논문집A
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• 제35권1호
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• pp.107-114
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• 2011

본 논문에서는 나노 래핑 표면의 형상과 레이저산란 패턴 사이의 실험적 모델링에 관한 연구를 하였다. 우선, 반사표면에서 나타나는 산란광 속성들을 고찰하여 암시야 기반의 레이저산란 검사 메커니즘을 구성하였다. 이 메커니즘을 이용한 레이저산란 패턴 분석의 경우, 나노 래핑 표면 형상으로부터 산란된 레이저산란 성분은 불규칙하게 사선형태로 교차됨을 알 수 있다. 또한, 실험 계획법을 기반으로 도출된 매개변수로 적용된 최적의 레이저산란 영상에서 나노 래핑 표면 거칠기와 레이저산란 성분 사이의 상관관계를 회귀분석법을 이용하여 수학적 모델링을 시도 하였다. 이 모델의 검증을 위해 나노 래핑 표면 3 종류의 거칠기에 대해 50 번의 반복실험을 수행한 결과, 제시된 수학적 모델은 실제 거칠기 값에 근접하게 추정할 수 있음을 보였다.

• 대한전기학회논문지
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• 제33권5호
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• pp.173-180
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• 1984

The spectra of scattering light fromlaser-produced plasma near its fundamental and second harmonic wavelength were observed respectively by means of spectroscopic technique. The experimental results and the generation mechanism of nonlinear effects such as the second garmonics and the brillouin scattering were analysed theoretically. The spectra of reflected laser light became wider than that of incident laser light. And the peak of spectrum of reflected light shifted to red-side from that of incident light. The second harmonic light is generated from the nonlinear interaction of the incident laser light and the electron plasma wave excited in resonance region by the oblique incidence of laser light to the plasma. The Brillouin backscattering from laser-produced plasmas of hydrogen and deuterium has shown an isotope effect in the red-side region of the generated second harmonic light. This isotope shift is explained by the parametric instability at the cutoff (resonance) region using frequency-and phase-matching conditions of the waves.

• 한국군사과학기술학회지
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• 제22권2호
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• pp.179-188
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• 2019

Laser beam is directional and small in divergence angle so that it is well qualified to deliver high intensity infrared energy into a coming MANPADS threat for aircraft survivability. The threat will be deceived and loose tracking of a target when it is exposed to the laser beam modulated relevant to the track mechanism of the threat. The laser beam goes through scattering inside the seeker of the threat and reach the detector in a stray light form, which is a critical phenomenon enabling jamming of the seeker. The mechanism of the laser beam based jamming against a pulse modulated infrared seeker is shown. Simulations are carried out to support the understanding of how the jam technique works.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.178-178
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• 2012

Neutral atom temperature was measured by Laser Rayleigh scattering method using neutral depletion by neutral heating with ideal gas law in Inductively coupled plasma. We observed sudden pressure change when plasma is turned on and off. We analyzed mechanism of neutral heating by employing zero-dimensional neutral and ion energy balance model simultaneously. The results showed that neutral atom temperature increase with ion density. The mechanism of neutral atom heating and cooling is mainly dominated by ion-neutral collision including elastic and charge-exchange collision and by wall cooling respectively.