• Title, Summary, Keyword: Laser scanning

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A Study on Generation of Laser Scanning Path and Scanning Control (레이저 주사 경로 생성 및 주사 제어에 관한 연구)

  • 최경현;최재원;김대현;도양회;이석희;김성종;김동수
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.1295-1298
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    • 2004
  • Selective Laser Sintering(SLS) method is one of Rapid Prototyping(RP) technologies. It is used to fabricate desirable part to sinter powder and stack the fabricated layer. To develop this SLS machine, it needs effective scanning path and the development of scanning device. This paper shows how to make fast scanning path with respect to scan spacing, laser beam size and scanning direction from 2-dimensional sliced file generated in commercial CAD/CAM software. Also, we develop the scanning device and its control algorithm to precisely follow the generated scanning path. Scanning path affects precision and total machining time of the final fabricated part. Sintering occurs using infrared laser which has high thermal energy. As a result, shrinkage and curling of the fabricated part occurs according to thermal distribution. Therefore, fast scanning path generation is needed to eliminate the factors of quality deterioration. It highly affects machining efficiency and prevents shrinkage and curling by relatively lessening the thermal distribution of the surface of sintering layer. To generate this fast scanning path, adaptive path generation is needed with respect to the shape of each layer, and not simply x, y scanning, but the scanning of arbitrary direction must be enabled. This paper addresses path generation method to focus on fast scanning, and development of scanning system and control algorithm to precisely follow generated path.

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Laser Scanning Technology for Ultrasonic Horn Location Compensation to Modify Nano-size Grain (나노계면 형성을 위한 초음파 진동자 위치보정을 위한 레이저 스캐닝 기술)

  • Kim, Kyugnhan;Lee, Jaehoon;Kim, Hyunse;Park, Jongkweon;Yoon, Kwangho
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.12
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    • pp.1121-1126
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    • 2014
  • To compensate location error of ultrasonic horn, the laser scanning system based on the galvanometer scanner is developed. It consists of the 3-Axis linear stage and the 2-Axis galvanometer scanner. To measure surface shape of three-dimensional free form surface, the dynamic focusing unit is adopted, which can maintain consistent focal plane. With combining the linear stage and the galvanometer scanner, the scanning area is enlarged. The scanning CAD system is developed by stage motion teaching and NURBS method. The laser scanning system is tested by marking experiment with the semi-cylindrical sample. Scanning accuracy is investigated by measured laser marked line width with various scanning speed.

Laser scanning display as an emerging technology

  • Mun, Yong-Kweun;Ko, Young-Chul;Choi, Won-Kyoung;Jeong, Hyun-Gu;Lee, Ju-Hyun;Lee, Jin-Ho
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.943-946
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    • 2004
  • We report the laser scanning display as an emerging technology. We show demonstration system of laser TV, Video image is made by using a high speed MEMS scanning mirror and a direct-modulated red diode laser. We designed and fabricated MEMS scanning mirror. The first demonstration system showed a NTSC-resolution video image with the image size of 5 inches. The successful development of compact laser TV will open a new area of home application of the laser light.

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Photopolymer Solidification Phenomena Considering Laser Exposure Conditions in Micro-stereolithography Technology (마이크로 광 조형에서 레이저 주사조건에 따른 광 경화성수지의 경화현상)

  • 이인환;조동우;이응숙
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.3
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    • pp.171-179
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    • 2004
  • Micro-stereolithography technology has made it possible to fabricate a freeform 3D microslructure. This technology is based on conventional stereolithography, in which a UV laser beam irradiates the open surface of a UV-curable liquid photopolymer, causing it to solidify. In micro-stereolithography, a laser beam of a few $\mu m$ diameter is used to solidify a very small area of the photopolymer. This is one of the key technological elements, and can be achieved by using a focusing lens. Thus, the solidification phenomena of the liquid photopolymer must be carefully investigated. In this study, the photopolymer solidification phenomena in response to variations in the scanning pitch of a focused laser beam was investigated experimentally. The effect of layer thickness on the solidification width and depth was also examined. These studies were conducted under the conditions of relatively lower laser power and relatively higher scanning speed. Moreover, the photopolymer solidification phenomena for the relatively higher laser power and lower scanning speed was investigated, too. In this case, comparing to the case of lower laser power and higher scanning speed, the photopolymer absorbed large amount of irradiation energy of the laser beam. These results were compared with those obtained from a photopolymer solidification model. From these results, a new laser-scanning scheme was proposed according to the shape of the 3D model. Samples by each method were fabricated successfully.

Laser Scanning Path Generation for the Fabrication of Large Size Shape

  • Choi, Kyung-Hyun;Choi, Jae-Won;Doh, Yang-Hoe;Kim, Dong-Soo
    • 제어로봇시스템학회:학술대회논문집
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    • pp.2175-2178
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    • 2005
  • Selective Laser Sintering(SLS) method is one of Rapid Prototyping(RP) technologies. It has been used to fabricate desirable part to sinter powder and stack the fabricated layer. Since the sintering process occurs using infrared laser having high thermal energy, shrinkage and curling of the fabricated part occurs according to thermal distribution. Therefore, the fast scanning path generation is necessary to eliminate the factors of quality deterioration. In case of fabricating larger size parts, the unique scanning device and scanning path generation should be considered. In this paper, the development of SLS machines being capable of large size fabrication(800${\times}$1000${\times}$800 mm, W${\times}$D${\times}$H) will be addressed. The dual laser system and the unique scanning device have been designed and built, which employ CO2 lasers and dynamic 3-axis scanners. The developed system allows scanning a larger planar surface with the desired laser spot size. Also, to generate the fast scanning paths, adaptive path generation is needed with respect to the shape of each layer, and not simply x, y scanning, but the scanning of arbitrary direction should be enabled. To evaluate the suggested method, the complex part will be used for the experiment fabrication.

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Distribution Analysis of the Local Critical Temperature and Current Density in YBCO Coated Conductors using Low-temperature Scanning Laser and Hall Probe Microscopy (저온 주사 레이저 및 홀소자 현미경을 이용한 YBCO 초전도 선재의 국소적 임계 온도 및 전류 밀도 분포 분석)

  • Park, S.K.;Cho, B.R.;Park, H.Y.;Ri, H.C.
    • Progress in Superconductivity
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    • v.13 no.1
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    • pp.28-33
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    • 2011
  • Distribution of the local critical temperature and current density in YBCO coated conductors were analyzed using Low-temperature Scanning Laser and Hall Probe Microscopy (LTSLHPM). We prepared YBCO coated conductors of various bridge types to study the spatial distribution of the critical temperature and the current density in single and multi bridges. LTSLHPM system was modified for detailed linescan or two-dimensional scan both scanning laser and scanning Hall probe method simultaneously. We analyzed the local critical temperature of single and multi bridges from series of several linescans of scanning laser microscopy. We also investigated local current density and hysteresis curve of single bridge from experimental results of scanning Hall probe microscopy.

High-speed angular-scan pulse-echo ultrasonic propagation imager for in situ non-destructive evaluation

  • Abbas, Syed H.;Lee, Jung-Ryul
    • Smart Structures and Systems
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    • v.22 no.2
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    • pp.223-230
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    • 2018
  • This study examines a non-contact laser scanning-based ultrasound system, called an angular scan pulse-echo ultrasonic propagation imager (A-PE-UPI), that uses coincided laser beams for ultrasonic sensing and generation. A laser Doppler vibrometer is used for sensing, while a diode pumped solid state (DPSS) Q-switched laser is used for generation of thermoelastic waves. A high-speed raster scanning of up to 10-kHz is achieved using a galvano-motorized mirror scanner that allows for coincided sensing and for the generation beam to perform two-dimensional scanning without causing any harm to the surface under inspection. This process allows for the visualization of longitudinal wave propagation through-the-thickness. A pulse-echo ultrasonic wave propagation imaging algorithm (PE-UWPI) is used for on-the-fly damage visualization of the structure. The presented system is very effective for high-speed, localized, non-contact, and non-destructive inspection of aerospace structures. The system is tested on an aluminum honeycomb sandwich with disbonds and a carbon fiber-reinforced plastic (CFRP) honeycomb sandwich with a layer overlap. Inspection is performed at a 10-kHz scanning speed that takes 16 seconds to scan a $100{\times}100mm^2$ area with a scan interval of 0.25 mm. Finally, a comparison is presented between angular-scanning and a linear-scanning-based pulse-echo UPI system. The results show that the proposed system can successfully visualize defects in the inspected specimens.

Effect of Nd:YVO4 Laser Beam Direction on Direct Patterning of Indium Tin Oxide Film

  • Ryu, Hyungseok;Lee, Dong Hyun;Kwon, Sang Jik;Cho, Eou Sik
    • Journal of the Semiconductor & Display Technology
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    • v.18 no.3
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    • pp.72-76
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    • 2019
  • A Q-switched diode-pumped neodymium-doped yttrium vanadate (YVO4, λ =1064nm) laser was used for the direct patterning of indium tin oxide (ITO) films on glass substrate. During the laser direct patterning, the laser beam was incident on the two different directions of glass substrate and the laser ablated patterns were compared and analyzed. At a low scanning speed of laser beam, the larger laser etched lines were obtained by laser beam incident in reverse side of glass substrate. On the contrary, at a higher scanning speed, the larger etched pattern sizes were found in case of the beam incidence from front side of glass substrate. Furthermore, it was impossible to find no ablated patterns in some laser beam conditions for the laser beam from reverse side at a much higher scanning speed and repetition rate of laser beam. The laser beam is expected to be transferred and scattered through the glass substrate and the laser beam energy is thought to be also dispersed and much more influenced by the overlapping of each laser beam spot.

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A Study on a Laser Scanning Vibrometer Using a Magnetostrictive Resonant Device (자기 변형 공진 기구를 이용한 레이저 스캐닝 진동측정기에 관한 연구)

  • 이정화;류제길;박기환
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.11
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    • pp.58-66
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    • 1998
  • A low power consuming laser scanning vibrometer is studied for its development. For its optical system, a laser interferometer is constructed to use the Doppler effect. In order to reduce the driving power of the scanning system, a small displacement of the scanning system is produced, which is achieved by using a magnetostrictive actuator. A sufficient rotating angle of the scanning system is obtained by using an amplified displacement from the resonant phenomena of a second order mechanical system composed of a mass and spring. The control of the magnetostrictive actuator using a Terfenol-D is performed without using a feedback system to help reduce the power consumption. The vibration analysis is made for the sinusoidal scanning input to have the space domain information from the time domain of the velocity of a vibration object. As a partial work of development of a tow power consuming laser scanning vibrometer, in this work, a scanning system which has the above features is developed and experimentally investigated. For the purpose of the optical system calibration, the vibration measurement for one axis is presented and the future works are discussed.

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DEM generation of Rock Slope using Laser Scanning and Digital Stereo Photogrammetry (3D laser scanning 및 수치사진측량을 이용한 암반 사면의 DEM 추출 기법)

  • 정창엽;박형동
    • Tunnel and Underground Space
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    • v.13 no.3
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    • pp.207-214
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    • 2003
  • To obtain Digital Elevation Model(DEM) from an exposed rock mass, techniques such as laser scanning and digital stereo photogrammetric technique are recently applied. We have obtained the DEM of the rock slope using above techniques in this study, and examined a suitability and improvement of the photogrammetry for the rock slope by overlapping the DEM. This study can be applied to the measurement of fracture orientations, the prediction of rock joint network, and the analysis on the change of the rock slope.