• 한국레이저가공학회:학술대회논문집
• /
• 한국레이저가공학회 2006년도 추계학술발표대회 논문집
• /
• pp.41-45
• /
• 2006

Auto focusing system to find optimized focal position of laser beam used for material process has been investigated by using fiber confocal method. Wavelength of laser diode (LD) and diameter of single-mode fiber we 780nm and $5.3{\mu}m$, respectively. Intensity distributions of beam reflected from the surface of mirror and silicon bare wafer have been observed in a gaussian form. Experimental results show that focal position obtained by LD is shifted from one observed from surface scribed by laser about $80{\mu}m$. It is due to the difference of wavelength and each divergence of between LD and laser used for material process. It is confirmed that auto focusing control system through position calibration has operated steadily.

• 한국멀티미디어학회논문지
• /
• 제9권9호
• /
• pp.1131-1138
• /
• 2006

본 논문에서는 지하에 매설된 통신 관로를 레이저 투영 영상 분석에 의해 검사하는 새로운 기법을 제안한다. 레이저 다이오드, 발광 다이오드와 카메라로 구성된 장비가 관내에 직접 투입되며, 레이저 다이오드는 관벽에 투영 영상을 생성하고 발광 다이오드는 내부 조명 장치로 사용되며, 카메라는 관로 영상을 획득한다. 카메라에서 전달된 다양한 조건의 관로 영상에 대해 투영 영역을 정확히 분할하기 위하여, 새로운 객차 모델과 다중 임계치 기법을 이용한다. 분할된 투영 고리의 형상은 최소 직경과 푸리에 표기자에 의해 표현하여 관로의 상태를 규칙에 기반하여 분류한다. 국부적인 최소 직경과 전역적인 푸리에 표기자를 모두 사용하므로 파손된 관로, 찌그러진 관로 등의 다양한 조건에서 높은 분류 성능을 나타낼 수 있으며, 여러 상태의 영상에 대한 실험 결과는 2% 미만의 오분류로 높은 성능을 나타냈다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2010년도 춘계학술대회 논문집
• /
• pp.1049-1050
• /
• 2010

• 한국통신학회논문지
• /
• 제18권12호
• /
• pp.1935-1944
• /
• 1993

레이저 다이오드단면의 최적 무반사 코팅 조건을 활성층 두께의 함수로써 세가지 간단한 수치해석 방법을 사용하여 계산하였다. 세가지 간단한 수치해석 방법을 사용하여 얻은 결과가 서로 가른 것은 각 방법에서 사용한 레이저 다이오드내의 유효 굴절율이 다르기 때문이다. 또한 간단한 수치해석 방법의 정확성을 검토하기위하여 정확한 수치해석 결과와 그 결과들을 비교하였다. 레이저 다이오드의 유효 굴절율이 도과모드를 구성하는 각 편면파의 입사간도에 따라 변해 굴절율이 도파모드를 구성하는 각 평면파의 입사각도 따라 변화하도록 설정한 방법이 TE와 TM 모드에 대해서 또 활성층 굴절율과 클래딩층의 굴절율차가 작은 경우 클 경우 각각에 대하여 정확한 수치해석 결과와 잘 일치함을 알 수 있었다.

• 한국입자에어로졸학회지
• /
• 제13권1호
• /
• pp.25-31
• /
• 2017

This paper offer the characteristics for the detection and classification of biological and non-biological aerosol particles in the air by using laser-induced-fluorescence (LIF) based Bio-aerosol Detection System (BDS). The BDS is mainly consist of an optical chamber, in-outlet nozzle system, 405 nm diode laser, an avalanche photo detector (APD) for scattering signal and photomultiplier tubes (PMT) for fluorescence signals in two different wavelength range ; F1, 510-600 nm and F2, 435-470 nm. The detection characteristics, especially ratio of fluorescence signal intensity were examined using well-known components : polystylene latex (PSL), fluorescence PSL, $2{\mu}m$ of SiO2 micro sphere, dried yeast, NADH, ovalbumin, fungicide powder and standard dust. The results indicated that the 405 nm diode laser-based LIF instrument can be a useful bio-aerosol detection system for unexpected biological threaten alter in real-time to apply for dual-use technology in military and civilian fields.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2000년도 제21회 KOSCO SYMPOSIUM 논문집
• /
• pp.168-174
• /
• 2000

A diode laser sensor system based on absorption spectroscopy techniques has been developed to measure $CO_2$ concentration and temperature non-intrusively in high temperature combustion environments using a 2.0 ${\mu}m$ DFB(Distributed Feedback) laser. Two optics was fabricated in pig-tail fashion and all optical components were implemented in a single box. The evolution of measurement sensitivity was done using test cell by changing sweep frequency and $CO_2$ concentration. Gas temperature was determined from the ratio of integrated line strengths. Species concentration was determined from the integrated line intensity and the measured temperature. The result show that the system has 2% error in wide operation frequency range and accuracy of $CO_2$ concentration was about 3%. The system was applied to measure temperature and concentration in the combustion region of a premixed $CH_4$ +air triangular flame. The measurement results of gas temperature agreed well with thermocouple results. Many considerations were taken into account to reduce optical noise, etalon effect, beam steering and base line matching problem. The evaluations results and actual combustion measurement demonstrate the practical and applicability for in-situ and real time combustion monitoring in a practical system.

• 한국광학회지
• /
• 제9권4호
• /
• pp.231-235
• /
• 1998

레이저 다이오드 뒷면 여기 방식을 이용한 Nd: YAG 레이저를 제작하고, 뒷면 여기 방식을 이용하였을 때, 들뜸 효율을 측정하였다. 포화 흡수체로 $Cr^{4+}$:YAG를 레이저 공진기 내부에 설치하여 수동형 Q-switching을 수행하였고, 그 때, 평균 출력, 펄스폭 및 반복율 특성등을 조사하였다. 수동형 Q-switching된 레이저의 펄스폭 및 반복율은 평균 출력 및 $Cr^{4+}$:YAG 결정의 낮은 강도 투과율(low intensity trasmission)에 따라 변화하였으며, 평균 출력은 최고 1 W, 펄스폭은 최저 51 nsec 까지 얻을 수 있었고 최고 약 40kHz의 고반복율로 동작하는 것을 관찰하였다.

• 한국정밀공학회지
• /
• 제16권7호
• /
• pp.40-50
• /
• 1999

Recently, a laser displacement sensor is widely used for the manufacturing automation. The sensor is generally composed of a diode laser and a light receiving device. The diode laser emits a laser beam and the receiving device detects the light reflected from the measured object. The object position is obtained based upon triangulation method. As a light receiving device, a PSD is usually utilized since its structure is very simple and rugged and has a high accuracy. Although the theoretical relationship for this sensor had been developed, the characteristics of the sensor have not been much experimentally studied. In this paper, several experimental results will presented. The measurement accuracy is affected by the surface conditions such as the reflectance characteristics, the angle of the object's surface and the laser intensity. In addition, it is found that the PSD and the signal processing circuit have nonlinearities and showed that those nonlinearities can be reduced by controlling the emitting laser intensity.

• 한국생산제조학회지
• /
• 제20권5호
• /
• pp.646-652
• /
• 2011

Recently, lots of automobile part manufacturers try to increase glass fiber content of their plastic parts to improve strength and impact-resistance. For this reason, injection mold requires high hardness and wear-resistant. Laser surface treatment is used to improve characteristics of wear and to enhance the fatigue resistance for injection mold. In this paper, high carbon steel (HP4MA) for injection mold material was heat-treated to harden surface by using high power diode laser (HPDL). To find the process parameters for laser surface treatment of HP4MA, many experiments are carried out as changing the parameters of surface temperature and travel speed of laser. From the results of the experiments, it has been shown that the maximum average hardness is approximately 711~739 Hv when the temperature and the travel of laser are $1,050^{\circ}C$ and 2 mm/sec.

• 한국수소및신에너지학회논문집
• /
• 제28권6호
• /
• pp.729-737
• /
• 2017

The measurement accuracy of Tunable Diode Laser Absorption Spectroscopy based Tomography (TDLAST) for the temperature and concentration fields are dependant upon the arrangement method of the used laser beams. This paper reports on the optimization of laser beam arrangements using phantom data. It has been verified that the measurement error of the TDLAST decreased with increase of laser beam numbers. Further, it has been confirmed that perpendicular arrangements between the horizontal and the vertical laser beams without additional diagonal laser beams shows the minimum measurement errors.