• Proceedings of the Korean Society of Laser Processing Conference
• /
• 2002.11a
• /
• pp.3-5
• /
• 2002

• Proceedings of the Korean Society of Laser Processing Conference
• /
• 2000.06a
• /
• pp.43-46
• /
• 2000

• Journal of Conservation Science
• /
• v.32 no.3
• /
• pp.377-384
• /
• 2016

There are physical and chemical method for removement of a lacquered layer existing on the surface when gilding an iron Buddha, these caused environmental pollution by surface degradation and is very noxious for conservation scientist's health. Thus, on this study, we conducted a lacquered layer removement experiments using Nd:YAG Laser which is contactless and eco-friendly. Specimens were made by polishing $5{\times}5$ size of iron(99.9%) specimens surfaces evenly and by differing of number of coating of unrefined lacquer, so there were thickness differences of $10{\mu}m$, $20{\mu}m$, and $30{\mu}m$. The laser machine used in this study was Nd:YAG Laser, and we used two wavelength modes; 1064 nm(160~180 mJ) for infrared light region and 532 nm(50~350 mJ) for ultraviolet light region. The experiment done by investigating the transition of specimens' surfaces with laser wavelength, energy, and numbers of investigation. The remain amount of lacquered layer surfaces before/after laser irradiation was investigated by stereoscopic microscope, observation by SEM, Non-contact Surface Roughness Measurement Device, and FT-IR etc. As a result of each analysis, we could verify the thickness of $10{\mu}m$, $20{\mu}m$ of lacquered layer removed without surface degradation when using 1064 nm wavelength with $1.0J/cm^2$ density. We could find out that Nd:YAG Laser is effective for removing remained lacquered layers when gilding an iron Buddha. In the future, when not only the metal has made various studies also wood lacquered furniture or the like, it seems to be utilized to remove the lacquer without surface damage.

• Korean Journal of Optics and Photonics
• /
• v.20 no.5
• /
• pp.276-280
• /
• 2009

A Cr:YAG crystal was used as a saturable absorber for passive Q-switching of a Nd:$YVO_4$ laser which was pumped by a 1-W continuous wave laser diode. The first surface of the Cr:YAG was high-reflection coated for the pump wavelength. The high-reflection coating improved the absorption efficiency of the pump beam in the Nd:$YVO_4$ through double pass absorption. It also prevented pump beam induced partial bleaching of the Cr:YAG. The peak-to-peak pulse fluctuation of passively Q-switched laser output was approximately 4 %. The minimum pulse-width was measured to be 7.11 ns. Also, the average pulse repetition rate was 9 kHz and the maximum output power was 16.27 mW.

• Korean Journal of Optics and Photonics
• /
• v.8 no.5
• /
• pp.357-361
• /
• 1997

We report the operation of a self-starting phase conjugate laser(PCL) oscillator which compensates intracavity phase distortion. The self-starting PCL in the population inverted Nd:YAG gain media produced an output energy of 200 mJ in a 20 ns single-longitudinal-mode pulse at 10Hz. And it showed well-defined Gaussian spatial profile.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.103-104
• /
• 2005

본 논문에서는 Nd:YAG($\lambda$=266 nm, pulse) 레이저빔을 PDMS 표면에 조사하여, 소수성 물질인 PDMS를 친수성 물질로 개질하였다. 이미 산소 플라즈마를 이용한 것과 오존을 이용한 PDMS 표면 개질에 관한 논문이 발표되었는데, 레이저를 이용한 표면 개질은 간단한 레이저 빛의 조사만으로 표면을 개질할 수 있는 장점이 있다. 본 논문에서는 레이저를 이용하여 PDMS 를 표면처리한 후에 접촉각 측정기를 이용해서 측정한 결과 접촉각 감소가 있었다. 묘면에 산소 함유량이 증가한 것을 확인함으로써 친수성 물질로의 표면 개질됨을 확인할 수 있었다.

• Proceedings of the Optical Society of Korea Conference
• /
• 2003.02a
• /
• pp.130-131
• /
• 2003

수술용으로 쓰이는 치과용 레이저로는 Nd：YAG, $CO_2$, Er：YAG 레이저들이 있다. 치료 부위에 따라 두 가지 응용으로 나눌 수 있다. 잇몸의 절개 등은 주로 $CO_2$나 Nd：YAG 레이저를 이용하여 정밀하게 그리고 출혈을 최소로 하는 레이저의 장점을 살리면서 시술하고 있다. $CO_2$레이저의 경우 강한 열적 손상작용 때문에 출력 조사 시간을 짧게 하여 사용하며, 열적 손상력이 낮은 Nd：YAG 레이저는 화이버를 접촉식으로 하여 화이버의 작은 면적의 높은 광밀도를 이용하여 시술하고 있다. (중략)

• Korean Journal of Optics and Photonics
• /
• v.14 no.5
• /
• pp.515-520
• /
• 2003

Characteristics of an amplifier with repetition rate of a few KHz is investigated. The continuous flash lamp pumped Nd:YAG laser head is used as an amplifier. The thermally induced birefringence of the laser medium is compensated and the depolarization is reduced to 5% in a double-pass amplifier. The amplification factor of a four pass amplifier reaches to about 3.2 at the repetition rate 5-10 KHz and the pulse width is lengthened from 40 ns to 48 ns.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1159-1165
• /
• 2003

The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. The major process parameters studied in the present laser welding experiment were position of focus, travel speed and laser power.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.9 no.5
• /
• pp.70-75
• /
• 2010

In this paper, laser marking systems dedicated to cylinderical parts was developed. We first develop the marking device which consists of Nd-Yag laser, galvano scanner and additional rotational axis, then develop algorithm for supporting the digital image with bmp data format. Additional rotational axis is so attached as to rotate the cylinderical parts for marking its whole surface. The image is separated into line by line and the separated line image is sent to galvano scanner while rotating the additional axis simultaneously. CxImage library, famous open source code, is employed for the image processing. The developed method was tested with various images and shows that it reduces marking time significantly without reducing marking quality.