• Bulletin of the Korean Chemical Society
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• 제31권9호
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• pp.2675-2678
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• 2010

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2199-2200
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• 2009

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 하계학술발표회
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• pp.64-65
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• 2003

Stereo-lithography using the two photon absorption(TPA) makes micro structures with great resolution. The technique is applied to correcting photomask, 3-D photonic crystal, 3-D optical storage, 3-D lithography and so on. In contrast to a conventional stereo-lithography with single-photon absorption which has a size problem caused by the geometrical diffraction limit, the stereo-lithography with TPA has no size limit. (omitted)

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.595-596
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• 2009

• 한국광학회지
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• 제17권1호
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• pp.75-80
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• 2006

펨토초 레이저 펄스에 의한 포토폴리머의 투과율 변화와 Eu 이온과 Sm 이온이 첨가된 sodium borate 유리의 형광파장의 변화를 이용하여 3차원 광메모리 가능성을 연구하였다. 780 nm의 모드잠금 타이사파이어 레이저를 이용하여 이광자흡수에 의해 DuPont 포토폴리머에서는 투과율을 변화시켰으며 이로 인해 $0.6{\mu}m$ 크기의 비트를 형성하였다. Sm 이온이 첨가된 재료에서는 이광자흡수로 인한 Sm 이온의 광환원을 이용하여 $4{\mu}m$ 크기의 형광 비트를 얻을 수 있었고 다층구조에서의 비트 형성을 시도하였다.

• 한국광학회:학술대회논문집
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• 한국광학회 2007년도 하계학술발표회 논문집
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• pp.329-330
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• 2007

Today some many types of 3D display are developed but that are not possibly multiviewer, multiview and full parallax. Our new research work uses the Quantum optic to develop 3D display. Quantum mechanically, we can think of the first photon making a virtual transition to the second state. If the second photon appears within the lifetime of that state, the absorption sequence to the third level can be completed. When the electron, located in the third state, shifts to the first state, that electron emits one visible photon. We controlled the two invisible lights to draw a pixel in volume.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.666-673
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• 2022

The optimization of a transmission type bremsstrahlung conversion target was carried out with Monte Carlo code FLUKA for intense pulsed electron beams with electron energy of several hundred keV for maximum photon fluence. The photon emission intensity from electrons with energy ranging from 300 keV to 1 MeV on tungsten, tantalum and molybdenum targets was calculated with varied target thicknesses. The research revealed that higher target material element number and electron energy leads to increased photon fluence. For a certain target material, the target thickness with maximum photon emission fluence exhibits a linear relationship with the electron energy. With certain electron energy and target material, the thickness of the target plays a dominant role in increasing the transmission photon intensity, with small target thickness the photon flux is largely restricted by low energy loss of electrons for photon generation while thick targets may impose extra absorption for the generated photons. The spatial distribution of bremsstrahlung photon density was analyzed and the optimal target thicknesses for maximum bremsstrahlung photon fluence were derived versus electron energy on three target materials for a quick determination of optimal target design.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.189-194
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• 2002

Two-photon resonant third photon ionization of atomic bromine $(4p^5\;^2P_{3/2}\;and\;^2P_{1/2})$ has been studied using a photoelectron imaging spectroscopy in the wavelength region 250 - 278 nm. The technique has yielded simultaneously both relative branching ratios to the three levels of $Br^+(^3P_2,\;^3P_{0.1}\;and^1D_2)$ with $4p^4$ configuration and the angular distributions of outgoing photoelectrons. The product branching ratios reveal a strong propensity to populate particular levels in many cases. Several pathways have been documented for selective formation of $Br^+(^3P_2)$ and $Br^+(^3P_{0.1})$ ions. In general, the final ion level distributions are dominated by the preservation of the ion core configuration of a resonant excited state. Some deviations from this simple picture are discussed in terms of the configuration interaction of resonant states and the autoionization in the continuum. The photoelectron angular distributions are qualitatively similar for all transitions, with a positive $A_2$ anisotropy coefficient of 1.0-2.0 and negligible $A_4$ in most cases, which suggests that the angular distribution is mainly determined by the single-photon ionization process of a resonant excited state induced from the third photon absorption.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1365-1368
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• 2004

A scheme to control the laser power and the exposure time was studied to fabricate precise microstructures using the nanostereolithography (nSL) process. Some recent works have shown that a three-dimensional (3D) microstructure can be fabricated by the photopolymerizing process which is induced by two-photon absorption (TPA) with a femtosecond pulse laser. TPA provides the ability to confine photochemical and physical reactions within the order of laser wavelength, so neardiffraction limit features can be produced. In the nSL process, voxels are continuously generated to form a layer and then another layer is stacked in the normal direction of a plane to construct a 3D structure. Thus, fabrication of a voxel with low aspect ratio and small diameter is one of the most important parameters for fabricating precise 3D microstructures. In this work, the mechanism of a voxel formation is studied and a scheme on the control of laser power and exposure for minimizing aspect ratio of a voxel is proposed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.159-160
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• 2007