• 한국광학회지
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• 제1권1호
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• pp.7-11
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• 1990

수은 원자 증기에 강한 레이저 광$(10-120GW/\textrm{cm}^2)$을 조사하여 수은 원자의 공명 다광자 이온화 과정을 연구하였다. 파장 560.7nm의 광자 4개를 흡수할 때 공명준위는 $6d ^1D_2$이다. 수은 증기압(0.1-3.0 Torr)과 레이저 파장(559-569nm)을 변화시키면서 큰 강도의 광원과 원자가 상호작용하여 생기는 AC Stark 이동과 line broadening의 변화를 조사하였고, 원자 밀도의 증가에 따라 이온화율의 증가가 둔화되다가 감소되는 것도 관측되었다. 이동계수 $\alpha$=0.6cm-1/GW/$\textrm{cm}^2$로 측정되었다. 특히, 이온화율의 레이저 강도 의존성을 나타내는 비선형 차수를 공명파장에서 측정한 결과 k=3을 얻었으며, 이론적인 결과와 비교하였다.

• Current Optics and Photonics
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• 제5권5호
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• pp.500-505
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• 2021

We demonstrated a wide-fan-angle flat-top irradiance pattern with a very narrow linewidth by using an aspheric lens and a long-pitch reflective diffraction grating. First, we numerically designed a diffraction-based linear beam homogenizer. The structure of the Al diffraction grating with an isosceles triangular shape was optimized with 0.1-mm pitch, 35.5° slope angle, and 0.02-mm radius of the rounding top. According to the numerical results, the linear uniformity of the irradiance was more sensitive to the working distance than to the shape of the Al grating. The designed Al grating reflector was fabricated by using a conventional mold injection and an Al coating process. A uniform linear irradiance of 405-nm laser diode with a 100-mm flat-top length and 0.176-mm linewidth was experimentally demonstrated at 140-mm working distance. We believe that our proposed linear beam homogenizer can be used in various potential applications at a precise inspection system such as three-dimensional morphology scanner with line lasers.

• 한국포장학회지
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• 제29권2호
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• pp.111-118
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• 2023

본 연구에서 연속형 레이저와 나노초 레이저의 경우에는 고분자와 물성 조건이 맞지 않아서, 고분자 필름 표면에 특정 패터닝이 구현되지 않았다. 그러나, 펨토초 레이저를 활용하여 HDPE, PP, PET 등의 식품포장 필름의 표면에 패터닝이 구현됨을 확인하였다. 따라서, 본 연구에서 식품포장 필름에서 펨토초 레이저 패터닝 공정 조건을 확립하였고, 싱글 펄스에 의한 대면적 원형 패턴, 싱글 펄스를 30%를 중첩한 대면적 거칠기 패턴, 직선 패턴, 직선 패터닝을 중첩한 대면적 거칠기 패턴, 직선 패터닝을 교차하여 격자 패턴 등의 표면 패터닝 필름을 제작하였다. 또한, 표면 패턴 구조와 크기에 따른 패터닝 HDPE, PP, PET 필름은 SEM, AFM, 접촉각 분석을 통하여 그 특성을 확인하였다. 펨토초 레이저 패터닝을 하지 않은 각 대조군 필름의 표면 대비 대면적 원형 패터닝 HDPE 및 PP 필름, 싱글 펄스를 30%를 중첩한 대면적 거칠기 패터닝 및 직선 패터닝을 중첩한 대면적 거칠기 패터닝 PET 필름의 표면은 27.1-37.5°의 접촉각을 나타냄으로써, 패터닝 후에 HDPE, PP, PET 필름은 친수성 표면으로 변화되었다. 반면, 나노-마이크로 크기의 돌기 표면구조를 갖고 있는 대면적 격자 패터닝 HDPE 필름의 경우에는 120.4°의 접촉각을 보임으로써, 패터닝 후에 소수성 표면으로 변화되었다. 따라서, 패터닝을 통해 친수성 표면으로 바뀐 필름들은 단백질, 세포, 바이러스 등을 비롯하여 식품의 물질들이 달라붙지 못하거나, 쉽게 떨어지는 엔티파울링 응용분야에 활용이 가능하다. 또한, 향후 좀더 정밀한 나노 및 마이크로 돌기 구조를 갖는 격자 패터닝을 통해 150° 이상의 초소수성 표면을 제작하게 된다면, 자가 청소(Self-cleaning) 등의 초소수성 표면 응용분야에 활용 가능할 것이다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.97-103
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• 2006

This work forcus on the development of gas sensor that measure the concentrations of exhaust gas using diode laser. Each diode laser for exhaust gas measurement is set to work at near-IR using both DA and WMS methods. Also use of fiber-coupled optical elements makes such a sensor rugged and easy to align. On-line data acquisition and processing can be performed with a PC running LabVIEW software, and absorption signals are measured simultaneously by multiplexing method. Finally, It were experimentally compared WMS (Wavelength Modulation Spectroscopy) with DA (Direct Absorption) for the accuracy.

• 대한기계학회논문집
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• 제19권4호
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• pp.908-917
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• 1995

The constant .DELTA.K fatigue tests are performed in SS41 and its weldments to investigate crack opening behavior and fatigue crack propagation behavior at each parts of weldment and its boundary layer. The weldments were annealed after welding for the purpose of relieving residual stress. Every weldments has notch at weld metal zone, and fatigue crack propagates from weld metal zone to vase metal zone perpendicular to weld line. The Laser ISDG method is used in order to determine the crack opening ratio, this method is more precise than indirect measurement method, and faster and easier than other direct measurement method.

• 한국생산제조학회지
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• 제21권4호
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• pp.633-638
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• 2012

The doctor blade is a core part of a laser printer and directly influences the printing quality. The main specifications for doctor blades ate for them to be precise and durable. It is necessary to study an automatic production system for doctor blades in order to obtain high-efficient manufacturing processes. In this paper, the technology and the design of the automatic production line has for manufacturing doctor blades has been researched. The automated manufacturing process consists of five steps, which are the supplying of raw material, shearing, bending, bracket supplying, and the laser-spot welding process. The proposed automatic manufacturing system allowed for faster and more reliable production of doctor blades.

• 대한기계학회논문집A
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• 제27권5호
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• pp.772-778
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• 2003

Polystyrene foam is easily melted and vapoured by heat, has a proper quality in the pattern manufacturing and has a low price. The objective of this study is to develop a rapid prototyping method fur polystyrene foam pattern manufacuring to use the eliminative pattern casting (EPC). Applying fur the rapid prototyping concept reversely, the unnecessary part of section is vapored away by heat source of laser beam. In order to examine the applicability between laser beam process and polystyrene foam material, the basic experiments such as hole, line, plane and contour process are carried out. With these results, various three-dimensional shape patterns are made and this rapid prototyping tool for polystyrene foam manufacturing.

• 대한의용생체공학회:의공학회지
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• 제28권3호
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• pp.392-396
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• 2007

In this paper, we develop a new system to visualize the blood flow map in skin tissue, using the technique of Laser Speckle Flowgraphy (LSFG). The measuring unit consists of the laser diode, imaging system, line sensor, scanning mirror, and one-board microcomputer. The speckle signal is analyzed and sent to a PC, where the blood flow in a tissue area of $14mm{\times}26 mm$ is evaluated and displayed in a 2-D color map. It is demonstrated that the new LSFG instrument is useful to evaluate the degree of allergic reaction in patch test.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.504-507
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• 2006

Airborn Lidar technology has been applied to diverse applications with the advantages of accurate 3D information. Further, Lidar intensity, backscattered signal power, can provid us additional information regarding target's characteristics. Lidar intensity varies by the target reflectance, moisture condition, range, and viewing geometry. This study purposes to generate normalized airborne LiDAR intensity image considering those influential factors such as reflectance, range and geometric/topographic factors (scan angle, ground height, aspect, slope, local incidence angle: LIA). Laser points from one flight line were extracted to simplify the geometric conditions. Laser intensities of sample plots, selected by using a set of reference data and ground survey, werethen statistically analyzed with independent variables. Target reflectance, range between sensor and target, and surface slope were main factors to influence the laser intensity. Intensity of laser points was initially normalized by removing range effect only. However, microsite topographic factor, such as slope angle, was not normalized due to difficulty of automatic calculation.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.231-231
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• 2006

We fabricated a polymer sub-microstructure for optical device application by two-photon-induced laser lithography technique. Polymer pattern could be minimized as small as ${\sim}100\;nm$. The photopolymerization resin contains laser-dye, thus promising a high level of the optical gain. We utilized the lithography technique to the photonic crystal application, where the template of the two-dimensional photonic crystal was modified by polymer gain medium as defect-shape and line-shape orientations. Photonic band gap effect from polymer-doped photonic crystals is expected to exploit the application such as organic solid-state laser device.