• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 하계학술발표회 논문집
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• pp.61-63
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• 2008

Parallel femtosecond laser processing using a computer-generated hologram (CGH) displayed on a liquid crystal spatial light modulator (LCSLM) is demonstrated. The use of the LCSLM enables to perform an arbitrary and variable patterning. This holographic femtosecond laser processing has advantages of high throughput and high light-use efficiency. A critical issue is to precisely control the intensities of the diffraction peaks of the CGH. We demonstrate some methods for the control of the diffraction peaks. We also demonstrate the laser processing with two-dimensional and three-dimensional parallelism.

• 한국레이저가공학회지
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• 제11권2호
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• pp.20-25
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• 2008

Polyimide is one of the useful materials in industry. The surface treatment of polyimide by a femtosecond laser can help accurate and fine fabrication of microstructure. And it can change the transmittance and reflectance of polyimide, too. We put femtosecond laser pulses on polyimide for rectangular or square type surface treaments and observe the change of transmittance and reflectance. Pulsewidth is 172 fs, laser power changes for fabrication are from 5 mW to 20 mW, and transmittance and reflectance are measured under 20m W, 300m W, and 920 mW. Pulse patterning is stable and almost no unwanted surface damage is shown. As power increases, working depth increases but working line width does not increase significantly. As speed changes, they also have same results. It shows the efficiency of a femtosecond laser is good and thermal damage is small for polyimide.

• 한국레이저가공학회지
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• 제9권2호
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• pp.11-15
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• 2006

We report experimental results on the high-speed micromachining using a femtosecond laser (800 nm, 130 fs, 1kHz) and galvanometer scanner system (Raylase, Germany). Periodic hole drilling of silicon and glass with the scan speed of 1-20 mm/s is demonstrated. Finally, we demonstrate the utility of the femtosecond laser application to ITO patterning by using a high-speed femtosecond laser scanner system.

• 세라미스트
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• 제10권3호
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• pp.91-97
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• 2007

Femtosecond laser micro-processing received much attention in the past decade. The nature of ultra-short light-matter interaction permits femtosecond laser to overcome the diffraction limit and realize precise micro-processing. The ultrahigh light intensity of the femtosecond laser allows sapece-selective microscopic modifications to materials based on multiphoton processes. In this paper, we review our recent research development on space-selective precipitation and control of functional crystals in glasses by an infrared femtosecond laser. The technique will open new possibilities in the fabrication of micro-optical components with various optical functions.

• 한국레이저가공학회지
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• 제15권2호
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• pp.1-5
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• 2012

Gelatin is used as a model for soft biological tissues in studying laser interaction with the soft tissues. In this work, we analyze the interaction between gelatin and excimer and Ti:Sapphire femtosecond laser under various conditions, especially by varying the laser, laser fluence and pulse number. The results show that swelling of the surface and ablation depth can be controlled by adjusting the process parameters.

• 한국레이저가공학회지
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• 제8권1호
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• pp.39-44
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• 2005

We report experimental results on the periodic patterning using a Ti:sapphire femtosecond laser (800nm, 100fs, 1kHz). Periodic structures with reproducible basic patterns are produced both on the surface and inside transparent materials. Period patterning for the application to display panel is widely investigated. Also, the submicron dot and line patterns are fabricated inside fused silica glass, which is important for the formation of diffraction grating in integrated optical circuit. finally, we demonstrate the utility of the femtosecond laser application to optical memory by fabricating the three-dimensional dot patterns.

• 한국레이저가공학회지
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• 제17권4호
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• pp.1-6
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• 2014

Femtosecond laser induced shock generation in water and vitreous humor of enucleated porcine eyeball was investigated. When focusing the femtosecond laser into the liquid mediums, the acoustic waves with a frequency of about 15.6kHz could be observed by using wide-band microphone. The amplitude of the acoustic signals from water has attained a maximum under a laser power of about 5mW. Further increment of the power results in a decrement of the acoustic signals due to nonlinear optical process including filamentation of laser beam. We have further investigated the effect of femtosecond laser induced acoustic waves by applying the laser pulse into enucleated porcine eyeball. The comparative studies on both healthy and diseased eyeballs led us propose that the femtosecond laser pulses could be utilized as a novel tools for treatment of partially detached retina layers from their choroid structures.

• 한국정밀공학회지
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• 제26권6호
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• pp.36-40
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• 2009

Development of maskless lithography techniques can provide a potential solution for the photomask cost issue. Furthermore, it could open a market for small scale manufacturing applications. Since femtosecond lasers have been found suitable for processing of a wide range of materials with sub-micrometer resolution, it is attractive to use this technique for maskless lithography. As a femtosecond laser has recently been developed, both of high power and high photon density are easily obtained. The high photon density results in photopolymerization of photoresist whose absorption spectrum is shorter than that of the femtosecond laser. The maskless lithography using the two-photon absorption (TPA) makes micro structures. In this paper, we present a femtosecond laser direct write lithography for submicron PR patterning, which show great potential for future application.

• 한국레이저가공학회지
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• 제14권1호
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• pp.1-5
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• 2011

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.

• Applied Microscopy
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• 제50권
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• pp.24.1-24.11
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• 2020

The development of the femtosecond laser (fs laser) with its ability to provide extremely rapid athermal ablation of materials has initiated a renaissance in materials science. Sample milling rates for the fs laser are orders of magnitude greater than that of traditional focused ion beam (FIB) sources currently used. In combination with minimal surface post-processing requirements, this technology is proving to be a game changer for materials research. The development of a femtosecond laser attached to a focused ion beam scanning electron microscope (LaserFIB) enables numerous new capabilities, including access to deeply buried structures as well as the production of extremely large trenches, cross sections, pillars and TEM H-bars, all while preserving microstructure and avoiding or reducing FIB polishing. Several high impact applications are now possible due to this technology in the fields of crystallography, electronics, mechanical engineering, battery research and materials sample preparation. This review article summarizes the current opportunities for this new technology focusing on the materials science megatrends of engineering materials, energy materials and electronics.