• Title, Summary, Keyword: Argon laser

Search Result 126, Processing Time 0.037 seconds

Experiments on Selective Laser Sintering of WC-Co Mixture for Rapid Metal Tooling (쾌속 금형 제작을 위한 텅스텐 카바이드와 코발트 혼합물의 선택적 레이저 소결 실험)

  • 김광희;조셉비만
    • Journal of the Korean Society of Marine Engineering
    • /
    • v.26 no.6
    • /
    • pp.661-669
    • /
    • 2002
  • Rapid tooling technique enables us to make dies and molds that produce prototype parts with the correct material at a substantially reduced cost and time. In this study, experiments on selective laser sintering of tungsten carbide-cobalt mixture were carried out to find optimal sintering conditions that will be applied to rapid metal tooling. The experiments were carried out within an air, an argon and a nitrogen atmosphere. Coupons of single layer were sintered at various laser powers, scanning speeds and scan spacings. Very severe oxidation took place within an air atmosphere. The oxidation is reduced significantly within an argon and a nitrogen atmosphere. The thickness of the sintered coupons is increased as the energy density, the laser energy Per unit scanned area, is increased. Several multi-layer sintering experiments were also carried out.

DETECTION OF OCCLUSAL CARIES USING LASER FLUORESCENCE (레이저 형광법의 교합면 우식증 탐지 효과)

  • Kim, Chang-Gi;Lee, Chang-Seop;Lee, Sang-Ho
    • THE JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY
    • /
    • v.29 no.4
    • /
    • pp.600-606
    • /
    • 2002
  • The purpose of this study was to evaluate the diagnostic validity of an incipient occlusal caries using argon laser fluorescence. Extracted human premolars and molars with enamel carious lesion of occlusal surface were assessed using visual examination, visual examination with probing, argon laser fluorescence and histologic depth of carious lesion. The results in each of all the three detection methods were compared to the assessment of histologic depth of carious lesion using polarized microscope. The results from the present study can be summarized as follows; 1. There was highly correlation between the histologic depth of occlusal caries and all three detection methods(P<0.01). 2. The reproducibility(kappa value) of the visual examination, visual examination with probing and argon laser fluorescence between the histologic depth of occlusal caries was 0.189, 0.128, 0.472. The highest correlation was seen between detection of occlusal caries by argon laser fluorescence and histologic scores by polarized microscope. The results from this study indicated that argon laser fluorescence considered to be accurate and reliable method in detecting occlusal caries.

  • PDF

Characteristics of low temperature poly-Si thin film transistor using excimer laser annealing (엑시머 레이저를 이용한 저온 다결정 실리콘 박막 트랜지스터의 특성)

  • Kang, Soo-Hee;Kim, Yong-Hoon;Han, Jin-Woo;Seo, Dae-Shik;Han, Jeong-In
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.430-431
    • /
    • 2006
  • This letter reports the fabrication of polycrystalline silicon thin-film transistors (poly-Si TFT) on flexible plastic substrates using amorphous silicon (a-Si) precursor films by sputter deposition. The a-Si films were deposited with mixture gas of argon and helium to minimize the argon incorporation into the film. The precursor films were then laser crystallized using XeCl excimer laser irradiation and a four-mask-processed poly-Si TFTs were fabricated with fully self-aligned top gate structure.

  • PDF

A STUDY ON THE EARLY DETECTION OF ENAMEL CARIES BY THE LUMINESCENCE EXCITED BY ARGON LASER (아르곤 레이저 광감각법의 법랑질 우식증 조기탐지 효과에 관한 연구)

  • Lee, Nan-Young;Lee, Chang-Seop;Lee, Sang-Ho
    • THE JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY
    • /
    • v.24 no.1
    • /
    • pp.313-324
    • /
    • 1997
  • The aim of the present study was to describe an safe and convenient method for the early detection of enamel caries using laser fluorescence. Fluorescence from natually carious lesion of human teeth illuminated by an argon laser(488nm) was observed and photographed using barrier filter. Intact enamel was found to fluorescence with a yellowish light. Whereas, incipient caries lesions in the enamel were dearly visible as dark areas in contrast to the fluorescence surroundings. For evaluation of accuracy of this method, lesion depth measured by the laser fluorescence in light microscope was compared with that polarizing microscope. The results from the present study can be summarized as follows : 1. Enamel caries of smooth surface was observed as pale white spot and undefined outline in ordinary light. Whereas, lesion was clearly visible as dark spot in laser fluorescence. 2. There was no difference between ordinary light view and laser fluorescence in occlusal surface and interproximal surface. 3. There was no significant difference between the lesion depth observed by laser fluorescence with light microscope and polarizing microscope. Apparent correlation exists between two groups.

  • PDF

The Porosity Control Technology of Lap Joint Welding Using Continuous Wave Nd:YAG Laser of the Low Carbon Steel SS41 (저탄소강 SS41 연속파형 Nd:YAG 레이저 겹치기 용접의 기공제어 기술)

  • Lee, Ka Ram;Hwang, Chan Youn;Yang, Yun Seok;Park, Eun Kyeong;Yoo, Young Tae
    • Journal of The Korean Society of Manufacturing Technology Engineers
    • /
    • v.22 no.4
    • /
    • pp.665-672
    • /
    • 2013
  • With the development of advanced processing technology, laser processing systems, which require high-quality precision processing, have attracted considerable attention. Although laser equipment is expensive, it enables quick processing and less deformation of materials. This technology is often applied to secondary batteries, which has thus farinvolved the use of argon tungsten inert gas (TIG) welding. However, the welding characteristics of argon TIG welding are not yet good, and a laser is used for welding to address this problem. In this study, lap-joint welding was conducted, and the desired welding characteristics were obtained when the laser power was 1800W and the laser beam travel speed was 1.8 m/min. Lap-joint welding was conducted on Ni-coated SS41. Two cases were compared. No pores were observed in the Ni-coated SS41 lap-joint welding part, and cracks appeared from the lap-joints. Moreover, the pole rod and tap were welded together in a T-joint form to improve the output of the secondary battery. T-joint laser welding showed better welding characteristics than TIG welding.

Output Enhancement of Rhodamine 6G Dye Laser by Rhodamine 560 Energy Transfer Dye (Rhodamine 560을 이용한 rhodamine 6G 색소 레이저의 출력 증가)

  • 장원권;이민희
    • Korean Journal of Optics and Photonics
    • /
    • v.5 no.2
    • /
    • pp.266-271
    • /
    • 1994
  • The output power and the energy of Rh-6G dye laser were enhanced by the mixture of Rh-560 dye whose fluorescence spectrum was coincident with the absorption spectrum of Rh-6G. The argon filled coaxial flashlamp used for pulsed pumping and argon laser for CW pumping. The concentration of Rh-6G dye was optimized in each pumping method before Rh-560 dye was mixed in Rh-6G dye solution. In the coaxial flash lamp pumped Rh-6G laser the output energy was increased about 30% when Rh-560 was mixed at 1% of Rh-6G concentration. In the case of argon laser pumping with multiline, the output power was increased 18% at the concentration of 2.5%. In the single line laser pumping, the output power was enhanced more efficiently. The power enhancements were 72% and 88% when the pumping wavelengths were 488 nm and 514.5 nm respectively. ively.

  • PDF

Spectral Analyses of Plasma Induced by Laser Welding of Aluminum Alloys (알루미늄 합금의 레이저 용접시 유기하는 플라즈마의 스펙트럼 분석)

  • 김종도;최영국;김영식
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
    • /
    • /
    • pp.292-300
    • /
    • 2001
  • The paper describes spectroscopic characteristics of plasma induces in the pulsed YAG laser welding of alloys containing a large amount of volatile elements. The authors have conducted the spectroscopic analyses of laser induced Al-Mg alloys plasma in the air and argon atmosphere. In the air environment, the identified spectra were atomic lines of Al, Mg, Cr, Mn, Cu, Fe and Zn, and singly ionized Mg lines, as well as the intense molecular spectra of A10 and Mg0 formed by chemical reactions of evaporated Al and Mg atoms from the pool surface with oxygen in the air. In argon atmosphere, Mg0 and AI0 spectra vanished, but AIH spectrum was detected. The hydrogen source was presumably hydrogen dissolved in the base metals, water absorbed on the surface oxide layer, or $H_2$ and $H_2O$ in the shielding gas. The resonant 1ines of Al and Mg were strongly self-absorbed, in particular, self-absorption of the Mg 1ine was predominant. These results show that the laser induced plasma was made of metal1ic vapor with relatively low temperature and high density.

  • PDF

Spectral Line Identification and Emission Characteristics of the Laser-Induced Plasma in Pulsed Nd:YAG Laser Welding (펄스 YAG 레이저 용접시 유기하는 플라즈마의 스펙트럼선 동정과 발광특성)

  • 김종도
    • Journal of the Korean Society of Marine Engineering
    • /
    • v.23 no.3
    • /
    • pp.360-368
    • /
    • 1999
  • The paper describes spectroscopic characteristics of plasma induced in the pulsed YAG laser welding of alloys containing a large amount of volatile elements. The authors have conducted the spectroscopic analyses of laser induced Al-Mg alloys plasma in the air and argon atmosphere. In the air environment the identified spectra were atomic lines of Al, Mg, Cr, Mn, Cu, Fe and Zn and singly ionized Mg lines as well as the intense molecular spectra of ALO and MgO formed by chemi-cal reactions of evaporated Al and Mg atoms from the pool surface with oxygen in the air. In argon atmosphere MgO and AlO spectra vanished but AlH spectrum was detected. the hydrogen source was presumable hydrogen dissolved in the base metals water absorbed on the surface oxide layer or $H_2$ and $H_2O$ in the shielding gas. The resonant lines of Al and Mg were strongly self-absorbed in particular self-absorption of the Mg line was predominant. These results show that the laser induced plasma was made of metallic vapor with relatively low temperature and high density.

  • PDF

Fabrication of Ultra Low Temperature Poly crystalline Silicon Thin-Film Transistors on a Plastic Substrate (고분자 기판 상에 제작된 극저온 다결정 실리콘 박막 트랜지스터에 관한 연구)

  • Kim, Yong-Hoon;Kim, Won-Keun;Moon, Dae-Gyu;Han, Jeong-In
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.445-446
    • /
    • 2005
  • This letter reports the fabrication of polycrystalline silicon thin-film transistors (poly-Si TFT) on flexible plastic substrates using amorphous silicon (a-Si) precursor films by sputter deposition. The a-Si films were deposited with mixture gas of argon and helium to minimize the argon incorporation into the film. The precursor films were then laser crystallized using XeCl excimer laser irradiation and a four-mask-processed poly-Si TFTs were fabricated with fully self-aligned top gate structure.

  • PDF