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Development of Debris-free Process using Erasable Ink for Polymer Ablation
신동식,이제훈,서정,김도훈,Shin, D.S.,Lee, J.H.,Suh, J.,Kim, T.H. Korean Society of Laser Processing 2005 한국레이저가공학회지 Vol.8 No.2
The excimer laser ablation of a polymer occurs by the excitation of chemical bonds to energy levels that are above the dissociation energy. In this process, however, fragmented debris is finally ejected explosively by the scission of bonds and accumulates on the material surface. In the present work, a process for eliminating surface debris contamination generated by the laser ablation of a polymer is developed. The proposed approach for removing surface debris utilizes an erasable ink pasted on a polymide. The ink pasted polyimide is ablated by KrF excimer laser. The surface debris ejected from the polyimide is then combined with the ink layer on the polymer. Finally, both the surface debris and the ink layer are removed using adhesive tape or alcohol solvent. The results suggest that the erasable ink method is a simple, low cost, and extremely effective debris eliminating process.
Ablation of Polypropylene for Breathable Packaging Films
Sohn, Ik-Bu,Noh, Young-Chul,Choi, Sung-Chul,Ko, Do-Kyeong,Lee, Jong-Min,Choi, Young-Jin Korean Society of Laser Processing 2006 한국레이저가공학회지 Vol.9 No.3
A Polypropylene (PP) film was ablated using a femtosecond laser with a center wavelength of 785 nm, a pulse width of 184 fs and a repetition rate of 1 kHz. Increments of both pulse energy and the shot number of pulses lead to co-occurrence of photochemical and thermal effect, demonstrated by the spatial expansion of rim on the surface of PP. The shapes of the laser-ablated PP films were imaged by a scanning electron microscope (SEM) and measured a 3D optical measurement system (NanoFocus). And, the oxygen transmission rate (ORT) of periodically laser-ablated PP film were characterized by oxygen permeability tester for modified atmosphere packaging (MAP) of fresh fruit and vegetable. Our results demonstrate that femtosecond pulsed laser is efficient tools for breathable packaging films in modifying the flow of air and gas into and out of a fresh produce container, where the micropatterns are specifically tailored in size, location and number which are easily controlled by laser pulse energy and pulse patterning system.
Measurement and Prediction of Damage Threshold of Gold Films During Femtosecond Laser Ablation
Balasubramani, T.,Kim, S.H.,Jeong, S.H. Korean Society of Laser Processing 2008 한국레이저가공학회지 Vol.11 No.4
The damage threshold measurement of gold films is carried out with ultrashort-pulse laser. An enhanced two temperature model is developed to encounter the limitation of linear modeling during ultrashort pulse laser ablation. In which the electron heat capacity is calculated using a quantum mechanical approach based on a Fermi-Dirac distribution, temperature-dependent electron thermal conductivity valid beyond the Fermi temperature is adopted, and reflectivity and absorption coefficient are estimated by applying a temperature-dependent electron relaxation time. The predicted damage threshold using the proposed enhanced modelclosely agreed with experimental results, demonstrating the importance of considering transient thermal and optical properties in the modeling of ultrashort pulse laser ablation.
Fabrication of Internal Gratings in PDMS Using a Femtosecond Laser
Park, Jung-Kyu,Cho, Sung-Hak,Yu, Jae-Yong,Kim, Jae-Gu,Sugioka, Koji,Hong, Jong-Wook,Heo, Won-Ha,Hwang, Kyung-Hyun Korean Society of Laser Processing 2011 한국레이저가공학회지 Vol.14 No.1
Photo-induced gratings m flexible PDMS (polydimethly siloxane) film are directly written by a high-intensity femtosecond (130fs) Ti: Sapphire laser (${\lambda}_p$ = 800nm). The refractive index modifications with $4\;{\mu}m$ diameters were photo-induced after the femtosecond irradiation with peak intensities of more than $1{\times}10^{11}W/cm^2$. The graded refractive index profile was fabricated to be a symmetric around the center of the point at which femtosecond laser by controlling both laser power and focused depth. The change on refractive index in the laser-modified regions was estimated to be approximately $10^{-3}$. The internal flexible symmetric diffraction gratings in PDMS film was successfully fabricated using a femtosecond laser.
Computer simulation for seam tracking algorithm using laser vision sensor in robotic welding
정택민,성기은,이세헌,Jung, Taik-Min,Sung, Ki-Eun,Rhee, Se-Hun Korean Society of Laser Processing 2010 한국레이저가공학회지 Vol.13 No.2
It is very important to track a complicate weld seam for the welding automation. Very recently, laser vision sensor becomes a useful sensing tool to find the seams. Until now, however studies of welding automation using a laser vision sensor, focused on either image processing or feature recognition from CCD camera. Even though it is possible to use a simple algorithm for tracking a simple seam, it is extremely difficult to develop a seam-tracking algorithm when the seam is more complex. To overcome these difficulties, this study introduces a simulation system to develop the seam tracking algorithm. This method was verified experimentally to reduce the time and effort to develop the seam tracking algorithm, and to implement the sensing device.
Interface between Robot and Scanner for Remote Laser Welding System Based on Time Synchronization
김정중,이준우,이주장,권경업,강희신,서정,Kim, Jeong-Jung,Lee, Joon-Woo,Lee, Ju-Jang,Kwon, Kyung-Up,Kang, Hee-Shin,Suh, Jeong Korean Society of Laser Processing 2013 한국레이저가공학회지 Vol.16 No.1
Remote laser beam welding (RLW) has the benefits of high speed and high quality welding, especially as applied to automotive industry. RLW is designed in a way that end effecter and head of scanner move simultaneously, and require the compensation for the motion of end effecter in order to weld proper position. In this paper, we show the algorithms of RLW that enable the end effecter to synchronize with scanner based on time. The proposed method consists of two algorithms. These algorithms make it possible for the moving end effecter to weld on desired place. The effectiveness of the algorithms is shown by experiments. 원격레이저 용접은(RLW)은 고속으로 고품질의 용접을 가능하게 하고 특히 자동차산업에 적용할 때 그 장점이 발휘된다. RLW은 로봇의 말단과 스캐너가 동시에 움직이도록 설계되는데 적합한 위치에 용접을 하기 위해서는 말단의 움직임에 대한 보상이 이루어져야 한다. 본 논문에서는 스캐너와 말단을 시간에 기반하여 동기화 하는 RLW을 위한 알고리즘을 보인다. 제안된 알고리즘은 두 개의 알고리즘으로 구성되어 있고 본 알고리즘으로 움직이는 말단이 원하는 위치에 용접을 가능하게 한다. 제안된 알고리즘의 효용성은 실험을 통해 보인다.
New CO Laser Technology Offers Processing Benefits
Held, Andrew Korean Society of Laser Processing 2015 한국레이저가공학회지 Vol.18 No.3
The development of a reliable, high-power source of mind-IR laser light gives process develop important tool with unique characteristics that will significantly impact a diverse range of applications.
Optical diffraction gratings embedded in BK-7 glasses by tightly focused femtosecond laser
Yoon, Ji Wook,Choi, Won Suk,Kim, Hoon Young,Cho, Sung-Hak Korean Society of Laser Processing 2014 한국레이저가공학회지 Vol.17 No.2
Optical embedded diffraction gratings with the bulk modification in BK-7 glass plates excited by tightly focused high-intensity femtosecond (130fs) Ti: sapphire laser (peak wavelength = 790nm) were demonstrated. The structural modifications with diameters ranging from 400nm to $4{\mu}m$ were photo-induced after plasma formation occurred upon irradiation with peak intensities of more than $1{\times}1013W/cm^2$. The graded refractive index profile was fabricated to be a symmetric around from the center of the point at which low-density plasma occurred. The maximum refractive index change was estimated to be $1.5{\times}10^{-2}$. The two optical embedded gratings in BK-7 glass plate were demonstrated with refractive index modification induced by the scanning of low-density plasma formation.
Internal modification in transparent materials using plasma formation induced by a femtosecond laser
Park, Jung-Kyu,Yoon, Ji-Wook,Cho, Sung-Hak Korean Society of Laser Processing 2012 한국레이저가공학회지 Vol.15 No.1
The fabrication of internal diffraction gratings with photoinduced refractive index modification in transparent materials was demonstrated using low-density plasma formation excited by a femtosecond (130 fs) Ti: sapphire laser (${\lambda}_p$=800 nm). The refractive index modifications with diameters ranging from $1{\mu}m$ to $3{\mu}m$ were photoinduced after plasma formation occurred upon irradiation with peak intensities of more than $2.0{\times}10^{13}W/cm^2$. The graded refractive index profile was fabricated to be a symmetric around from the center of the point at which low-density plasma occurred.