• 한국광학회지
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• 제26권2호
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• pp.98-102
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• 2015

PZT를 검출기로 사용하는 광음향 분광 측정법으로 고체레이저의 방사양자효율을 측정하였다. 반도체레이저 여기 Nd:S-VAP 레이저에서 레이저가 발진하고 있을 때 약 58.3 %의 양자효율을 얻었다. 방사양자효율의 측정은 레이저 공진기의 최적화를 가능하게 하는 한 방법임을 제시하였다.

• Medical Lasers
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• 제7권1호
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• pp.6-12
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• 2018

Introduction Energy-based devices allow for a more rapid and efficient ligation of blood vessels during operations. In the present study, we evaluated the feasibility of a laser as an alternative energy source for the vessel sealing system and determined the optimal condition of laser for an effective vessel sealing through histologic examination. Materials and Methods The arteries (5 mm diameter) harvested from porcine legs were compressed between two glass-slides to eliminate its luminal space and were irradiated with 1,470-nm diode laser under various sealing conditions, including laser power (5-30 W), irradiation time (5 or 10 seconds), and focus mode (focus or defocus). Subsequently, the irradiated vessels were fixed in 4% formaldehyde and then processed to paraffin block. The paraffinized sample was sectioned and stained with hematoxylin and eosin for histological evaluation. Results The extent of tissue change was positively correlated with duration and power of laser. In defocus mode, the irradiated vessels showed sufficient tissue denaturation for sealing effect without severe tissue destruction. Moreover, among the various conditions of irradiation, laser power between 15 and 20 W, as well as exposure time of 5 seconds were appropriate for sealing the blood vessels. Conclusion Adequate power and irradiation duration of laser can render blood vessels to be sealed effectively, although the higher power of laser may be required to cut the vessels.

• 한국레이저가공학회지
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• 제9권3호
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• pp.7-13
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• 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 are 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.

• 대한전자공학회논문지SD
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• 제41권12호
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• pp.51-57
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• 2004

본 논문에서는 폐경로를 통한 Fabry-Perot 레이저의 자기궤환 레이저 발진 현상을 이용하여 새로운 광섬유 길이 측정 방법을 제안하였다. Fabry-Perot 레이저에 변조전류를 인가하여 생성된 광펄스를 피측정 광섬유를 포함하는 폐경로를 통과한 후 다시 레이저로 입사시키면 특정 변조주파수에서 자기궤환 레이저 발진이 유도될 수 있다. 제안된 측정법에서는 특정 모드에서 자기궤환 레이저 발진을 유도하기 위한 변조주파수들을 측정하고, 이 변조주파수들 사이의 차를 이용하여 광섬유의 길이를 계산하도록 한다. 제안된 측정법을 이용하여 0.1 ∼ 75 km 범위의 피측정 광섬유의 길이 측정을 수행하였고, 측정결과는 기존의 상용 계측기를 사용한 측정 결과와 잘 일치함을 실험적으로 검증하였다. 상용 계측기와의 상대 오차는 0.24 % 이하였고, 반복측정오차(repeatability)는 0.1 % 보다 작았다.

• 한국광학회지
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• 제21권3호
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• pp.111-117
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• 2010

레이저 프린터 및 OA복합기기 내부의 감광 드럼에 빛을 조사하는 핵심 광 모듈인 Laser Scanning Unit(LSU)의 광원으로 사용할 수 있는 발진파장 780 nm, 광 출력 10 mW의 모노리식 집적형 8빔 레이저 다이오드를 개발하였다. 개발된 8-빔 소자의 레이저 빔들의 각각의 물리적 간격은 $30\;{\mu}m$ 이며, 각 빔을 독립적으로 작동시키기 위해서, 공중배선공정을 신규로 개발하였다. 개발된 8빔 레이저 다이오드의 전기 및 광학적 특성 측정 결과 레이저 프린터 및 복합기의 LSU에 사용 가능함을 검증하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.68-69
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• 2009

Heat Assisted Magnetic Recording (HAMR) is one of the most promising candidates for high density magnetic storages over 1 Tb/$in^2$ areal density. Since the precise light delivery to the head is a key factor to realize HAMR application, it is required to establish the light delivery using micro laser module and micro actuator. For the careful control of micro actuator, a laser module was designed including laser diode, optical fiber, collimating lens, and fabricated V-groove substrate. In addition, the basic aligning method between the laser module and HAMR head was studied by the detection of current change in photo diode due to the amount of reflected light from the head.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.476-477
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• 2009

The smallest green laser containing a built-in temperature controlling unit has been demonstrated. The device volume was just 0.5 cubic centimeters, which is nearly the same size as existing red and blue diode lasers, has an electrical-to-optical conversion efficiency of 10% and 150 mW power output. Furthermore as an alternative approach for compact green laser development, a quasi-phase matching method with wide spectral bandwidth for the reduction of speckle noise will be presented.

• 반도체디스플레이기술학회지
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• 제17권4호
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• pp.37-41
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• 2018

$Y_3A_{l5}O_{12}:Ce^{3+},Pr^{3+}$ single crystal phosphor was prepared by floating zone method. single crystal was confirmed to have a Ia-3d (230) space group of cubic structure and showed regular morphology. The optical properties, single crystal exhibited a emission band from green, yellow wide wavelength and 610nm, 640nm red wavelength vicinity. The luminance maintenance rate was decreased by phonon with increasing temperature, but high luminance is maintained more than powder phosphor. In addition, $Y_3A_{l5}O_{12}:Ce^{3+},Pr^{3+}$ single crystal phosphor was applied to a high power blue laser diode, we implemented high power white laser lightings. and it was confirmed that thermal properties over time, due to the effective heat transfer of complete crystal structure. We confirmed that excellent radiant heat properties than powder phosphor was applied to a high power white laser diode.

• 한국광학회지
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• 제17권3호
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• pp.273-277
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• 2006

홀버닝 광메모리의 광원으로서 상용 반도체 레이저 다이오드에 Littman형 및 고정방향 Littrow형 외부공진기를 결합하여 파장가변 레이저 다이오드 시스템을 제작하고 성능을 비교 분석하였다. 두 형태의 파장가변 레이저 다이오드 시스템 모두 0차 출력광은 단일종모드로 동작하며 CFP(Confocal Fabry-Perot)의 분해능인 9MHz이내의 선폭을 예상할 수 있었으며 다이오드 구동전류 140mA 및 동작 온도 $25^{\circ}C$의 조건하에서 거울 및 회절격자를 수동나사로 회전시키는 성긴 튜닝시 Littman형은 5.375nm, 고정방향 Littrow형은 13.65 nm이상의 파장가변 범위를 보였고 PZT (Piezoelectric Transducer)에 200Hz의 톱니파 전압을 인가해서 거울을 회전시키는 미세 튜닝 시 두 형태 모두 0.042nm의 범위 내에서 연속적인 파장가변이 가능하였다. 특히 고정방향 Littrow형 외부공진기는 출력광의 방향이 바뀌는 기존의 단점을 보강하였으며, 또한 외부공진기의 길이에 따른 최대파장가변 범위를 측정하였다.

• Journal of Korean Dental Science
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• 제14권2호
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• pp.69-78
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• 2021

Purpose: The primary objective of this study was to evaluate the change in the temperature of the adhesive resin in polycrystalline ceramic brackets irradiated using a diode laser at different irradiation energy levels and times. Materials and Methods: For the measurement of the temperature of the adhesive resin, it was applied at the base of the ceramic bracket, a thermocouple was placed at the center of the base surface, the bracket was placed on prepared resin specimens for light curing, and a laser was irradiated to the center of the bracket slot at 5, 7, and 10 W. For the measurement of the temperatures of the enamel under the bracket and pulp cavity, extracted premolar was fixed to a prepared mold and the ceramic bracket was bonded to the buccal surface of the premolar. The Kruskal-Wallis H test and Friedman test were used for statistical analysis. Result: At 5 W, the temperature of the adhesive resin did not reach the resin softening temperature of 200℃ within 30 seconds. At 7 W, it reached 200℃ when the ceramic bracket was irradiated continuously for 28 seconds. At 10 W, it reached 200℃ when the ceramic bracket was irradiated continuously for 15 seconds. During laser irradiation, the temperature of the enamel under the bracket increased by over 5℃ within 15 seconds. Conclusion: The use of diode laser irradiation for bracket debonding should be carefully considered because the pulp cavity temperature increases by over 5℃ within the irradiation time for resin thermal softening.