• Title/Summary/Keyword: Laser

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Micro-machining of nickel by picosecond laser ablation (피코초 레이저를 이용한 니켈의 미세가공 특성)

  • Shin D.S.;Lee J.H.;Suh J.;Noh J.W.;Chung Y.W.;Kim J.C.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.653-654
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    • 2006
  • In case of ultrashort laser ablation of metals, the transfer of energy from the electronic system causing strong absorption of laser light to the lattice needs relaxation times of the order of some picoseconds. Under the above theoretical background, nickel was ablated using femtosecond, picosecond and nanosecond laser. As a result, nickel ablation by picosecond laser and femtosecond laser, which are called ultrashort laser, has similar machinability because of relaxation time of metals, whereas nanosecond Nd:YAG laser has lower absorption, higher thermalization effect in comparison with ultrashort laser.

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Production of CO2 Laser Forming Machine for Bending of Sheet Metal Using the FE-Analysis (유한요소해석을 이용한 박판 벤딩용 CO2 레이저 성형기 제작)

  • Ko D.C.;Lee C.J.;Kim B.M.
    • Transactions of Materials Processing
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    • v.15 no.4 s.85
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    • pp.319-325
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    • 2006
  • The laser forming process is a new flexible forming process without forming tools and external force, which is applied to various fields of industry. Especially, applications of the laser forming process focused on cutting, welding and marking process. In this paper, the laser bending process of sheet metal which is heated by laser beam and formed by internal stress is simulated by using thermo elastic-plastic analysis model. Based on the result of FE-analysis, the laser bending machine is made to obtain reliable data for sheet bending. Under the same condition as FE-analysis, the laser bending experiment has been performed to ver 펴 the result of FE-analysis and good agreement has been obtained between FE-analysis and experiments. Additional laser bending experiments have been performed to evaluate the laser bending machine.

Design of online damage images detection system for large-aperture mirrors of high power laser facility based on wavefront coding technology

  • Fang, Wang;Qinxiao, Liu;Dongxia, Hu;Hongjie, Liu;Tianran, Zheng
    • Nuclear Engineering and Technology
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    • v.53 no.9
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    • pp.2899-2908
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    • 2021
  • The laser transport system of the high power laser facility is mainly composed of large-aperture laser transport mirrors (TMs). Obtaining the high-resolution online damage images during the operation, which is of great significance for operating safely of the mirrors and the facility. Based on wavefront coding, pan-tilt scanning and image stitching technologies, an online laser-damage images detection system is designed, and it can achieve high-precision detection of surface characteristics of large-aperture laser transport mirrors. The preliminary simulation proves that the system can solve the depth of field matching problem caused by pan-tilt tilt imaging and achieve higher resolution.

Investigation of Zircaloy-4 weldability using a pulsed Nd:YAG laser (펄스형 Nd:YAG 레이저를 이용한 지르칼로이-4 용접특성 조사)

  • 김수성;김덕현;김철중;이종민
    • Journal of Welding and Joining
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    • v.9 no.1
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    • pp.23-31
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    • 1991
  • Laser beam weldability of zircaloy-4was investigated using a pulsed Nd: YAG laser of 200W average power. Mechanical properties of laser and GTA bead-on-plate welded zircaloy-4 test specimens were compared. The influence of plasma generated during laser welding was analyzed and optimum laser welding parameters were investigated.

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A Study of Laser Repair for Thin Film Pattern (박막 패턴의 레이저 리페어 연구)

  • 강형식;홍성준;최종윤;홍순국;전태옥
    • Laser Solutions
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    • v.1 no.1
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    • pp.39-44
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    • 1998
  • Laser ablation system for microscopic defect in thin film pattern was developed in this study. For the varification of this study, several laser ablation tests were accomplished. The ablated shape of thin film and the surface of base glass were analyzed by use of microscopic tools and EPMA. After some tests of thin film, the specification of laser and optical unit(max. laser energy is 25mJ, wavelength is 532nm, Q-switched Nd-YAG laser, frequency is 20Hz, Auto-focus unit is LD type.)

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Ultrafast Laser Micro-machining Technology (극초단 펄스 레이저 응용 미세가공기술)

  • Lee, Jae-Hoon;Sohn, Hyon-Kee
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.2
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    • pp.7-12
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    • 2010
  • Due to the extremely short interaction time (< $10\times10^{-12}$sec) between laser pulse and material, which enables the minimization of heat affection, ultrafast laser micro-machining has rapidly widened its applications. In this paper, the characteristics of ultrafast laser micro-machining have been reviewed and experimentally demonstrated in laser drilling of silicon wafer and in laser cutting of rigid PCB.

Study on the Terror with Laser Weapons (레이저무기의 테러위협에 관한 연구)

  • Kim, Doo-Hyun
    • Korean Security Journal
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    • no.3
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    • pp.385-405
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    • 2000
  • In the Present thesis, at temps were to study with the study on the terror with laser weapons. Chapter I which sets out purpose, scope and method. Chapter II concerns the general definition of laser weapons. Chapter III explain at length overview about development of laser weapons. Chapter IV suggest the terror with laser weapons and the counterplan against it. It is followed by concluding observation made in chapter V. To we operated security systems effectively, these need to be regulated according to a security measures organizations, laser facilities and equipments, laser plan and protective force, laser operations and so forth.

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Microbump formation during laser texturing of glass substrates (유리기층의 레이저 텍스쳐링에 의한 미소융기의 형성)

  • 김동식;오부국
    • Laser Solutions
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    • v.4 no.3
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    • pp.40-44
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    • 2001
  • Microbump formation during CO$_2$ laser texturing of glass substrates is examined in this paper. Experimental results show that different bump shapes (dome-shaped, with a central dimple, and with a peripheral rim) are generated depending on the laser fluence. A theoretical model for the process is suggested based on thermoelastic behavior but limited only to the dome-shaped bump. The dimensions (maximum height and base area) of the bump shows a logarithmic dependence on laser fluence as expected from the theory. Numerical computation reveals that the effect of thermal diffusion is not negligible for relatively long laser pulses.

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Optimization of Laser Photolithography Micromachining Technique based on Taguchi Method (다구찌 방법을 이용한 레이저 포토리소그라피 미세패턴가공 기술의 최적화)

  • Baek, Nam-Kook;Kim, Dae-Eun
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.871-875
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    • 2001
  • Laser photolithography technique is useful for fabricating micro-patterns of silicon wafers. In this work, the laser photolithography micromachining technique is optimized based on Taguchi method. Sensitivity analysis was performed using laser scanning speed and laser power level as the parameters. The results show that for the photoresist used in this work, a laser scan speed of $70{\mu}m/s$ at 50mW laser power gives the best result.

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고출력(25GW)글라스레이저시스템의 개발에 관한 연구

  • 강형부
    • 전기의세계
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    • v.30 no.9
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    • pp.582-588
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    • 1981
  • The laser parameters such as a population inversion density, a stimulated emission cross section and loss factor in the glass laser amplifier medium were experimentally determined in order to analyse the properties of laser amplification. Using these parameters, the rate equations were approximately solved and the properties of laser amplification were analysed. An experiment of two-stage amplifier of Q-switching laser pulse was performed and the maximum output power was 1.1 GW, 33J. The several problems such as a laser solarization and a laser coupling in laser amplification were resolved.

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