• Journal of the Korean Chemical Society
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• v.38 no.1
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• pp.34-40
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• 1994

First observation of uranium using a diode laser was published recently. The experiment was performed by the optogalvanic spectroscopy using diode lasers. A laser source causes the current change in a hollow cathode discharge lamp when metal atoms in plasma absorb the diode laser light. The optogalvanic signal is collected by detecting the current change. This work is the extended investigation of our previous research, the uranium detection using a diode laser. New electronic transitions of uranium and thorium in 775∼850 nm were investigated using diode lasers. In addition, the Rb(Ⅰ) optogalvanic spectra at 780.02 nm and 794.76 nm were studied. The Rb(Ⅰ) spectrum at 780.02 nm showed the isotopic features and hyperfine splittings. This work provides a key idea that the diode lasers are useful in the specrochemical analysis of the radioactive actinides that have a rich spectrum with transitions which can be easily reached with AlGaAs diode lasers. Also, this study shows that the diode lasers can be an important tool to find the spectroscopic parameters of actinides and rare earth elements which have not known.

• Journal of the Korean Chemical Society
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• v.34 no.3
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• pp.255-259
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• 1990

The nitrogen-laser flash photolysis apparatus has been set up to detect directly the transient produced from the excited Benoxaprofen (BXP). The function of the instrument has been tested by using anthracene as a standard sample. The laser photoexcitation of BXP in ethanol has been carried out under a constant stream of $N_2$ gas and a transient absorption spectrurn has been recorded over the 400-600 nm. The effects of oxygen and ${\beta}-carotene$ on the transient spectrum reveal that thee maximum transient absorption at 415 nm is attributed to the triplet state of BXP and the triplet energy of BXP is above 22 Kcal/mole. In addition to the triplet state, another transient species has been observed to be produced, which is probably a radical form of BXP. The photosensitization mechanism of BXP is discussed based on these results.

• Korean Journal of Optics and Photonics
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• v.9 no.2
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• pp.111-116
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• 1998

Thirteen InGaAs/InGaAsP separate-confinement heterostructure multiple quantum well lasers were designed such that the strain in the active layer from 0.9% compressive strain to 1.4% tensile, and their threshold current density was caluculated to see the effects of strain on the threshold current density. The well width was adjusted such that the bandgap of the quantum well is 1.55 ${\mu}{\textrm}{m}$, For the calculation of the band structure and transition matrix element needed for the gain calculation, a block diagonalized 8$\times$8 second-order $\to{k}.\to{p}$ Hamiltonian was used to incorporate the conduction band nonparabolicity and the valence band mixing. The threshold current density shows discontinuity at 0.4% tensile strain where the first heavy-hole subband and the first light-hole subband cross and at 0.5% tensile strain where the second conduction subband begins to exist. The threshold current density at room temperature has a maximum around these 0.4-0.5% tensile strains, and as strain varies in either direction it decreases first and then increases a little after a local minimum. This calculated trend is consistent with the other reported experimental results. We discussed the results of this calculation in comparison with other theoretical or experimental papers on the effect of strain.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.106-112
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• 1994

The injection-locking of the broad-area diode laser was analysed by using the Fabry-Perot model. The far-field pattern of the output beam was able to be treated by superposing the individual beams emitted from the front facet due to the multiple reflections between the front and rear facets. and the exact near and far field patterns were obtained. The angle-steering effect according to change of the incident frequency was changed was calculated and found to be 0.022 degree/GHz with a bandwidth of 120 GHz.20 GHz.

• Journal of Welding and Joining
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• v.17 no.2
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• pp.53-60
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• 1999

Conventionally, CCD camera and vision sensor using the projected pattern of light is generally used to inspect the weld bead defects. But with this method, a lot of time is needed for image preprocessing, stripe extraction and thinning, etc. In this study, laser vision sensor using the scanning beam of light is used to shorten the time required for image preprocessing. The software for deciding whether the weld bead is in proper shape or not in real time is developed. The criteria are based upon the classification of imperfections in metallic fusion welds(ISO 6520) and limits for imperfections(ISO 5817).

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.98-99
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• 2002

대표적인 II-VI족 극성 반도체 결정인 ZnTe[001]와 ZnCdTe MQW에서 시료의 에너지 띠보다 낮은 에너지의 펨토초 티타늄 사파이어 레이저를 이용하여 결맞는 포논을 발생시키고 그 특성을 관찰하였다. 결맞는 포논의 신호는 그림1)과 같이 반사 및 투과형 전기 광학적 샘플링(Reflective/Transmissive Electro-Optic Sampling： REOS/TEOS)방법과 여기-탐사광 방법으로 시간 영역에서 측정하였다. (중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.10-10
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• 2004

유전율이 서로 다른 물질을 나노 크기로 주기적으로 배열하여 황자 띠간격(Photonic bandgap)을 이루게 하는 광결정(Photonic crystal)에 인위적인 결함을 부가하여 광파워 분배 및 Mux/Demux 등 광회로 기능 수행을 할 수 있도록 집적화한 광도파로 소자가 미래형 정보통신사회를 위한 초고집적화, 초고속화, 저전력 및 신기능 등의 특성을 위하여 요구된다. 이러한 나노 광결정 소자는 다양한 방법으로 제작이 시도되고 있는데, 나노 임프린트 기술은 실장밀도가 높으며, 수십 나노급의 패턴이 주기적으로 배열된 구조물의 성형에 큰 장점이 있어서 본 연구에서 다루어졌다.(중략)

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.97-103
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• 1999

Zinc sulfide is a ll-VI compound with a large direct band gap in the near-UV region and a promising material for blur-light emitting diode and laser diode. It was identified that the structure had zinc blonde structure through the analysis of X-ray diffraction patterns. It's lattice constant was measured to be $a_o=5.411{\AA}$. The optical absorption, photocurrent, and photoluminescence spectra were measured to investigate the optical properties of zinc sulfide single crystal. The optical energy band gap measured at room temperature was 3.61eV The energy band gap of zinc sulfide annealed in zinc vapor at $800^{\circ}C$ was lower 0.1eV than that of as-grown zinc sulfide through the analysis of the photocurrent spectra. The photoluminescence spectra were measured ranging from 30K to 293K for the two cases of as-grown and annealed zinc sulfide. As-grown ZnS single crystal had peaks at 350nm, 392nm, 465nm, and annealed zinc sulfide had peaks at 349nm.

• Korean Journal of Optics and Photonics
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• v.6 no.1
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• pp.33-38
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• 1995

We have measured the excited state absorption in $Ce:YAlO_{3}$, crystals for the first time and assigned it for a 5d$\rightarrow$conduction band transition. Two broad absorption bands were observed at 555 nm and 465 nm fowllowing the 308 nm XeCl laser excitation and their cross sections and oscillator strengths were calculated. We have also measured the fluorescence lifetimes in between 300 K and 700 K to study the nonradiative relaxation from the lowest 5d state of $Ce^{3+}$ ions and explained ESA and the transition process from the state in terms of a configurational coordinate.dinate.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.2
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• pp.37-43
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• 2007

In this paper, laser vision sensor is used to detect some defects any $co_{2}$ welded specimen in hardware. But, as the best expression of defects of welded specimen, the concept of segment splitting method and mean distance are introduced in software. The developed GUI software is used for deriding whether any welded specimen makes as proper shape or detects in real time. The criteria are based upon ISO 5817 as limits of imperfections in metallic fusion welds.