• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.291-296
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• 1997

The slotted type of hollow copper cathode was constructed and tested for its geometric stability and usability for laser operation at 780nm. The peak output power of copper ion laser emission was measured for different operating conditions. The IR-laser power was dependent on the parameters of the geometry of the hollow cathodes, discharge current and gas fillings. The peak power decreased with increasing neon pressure over 60%. One reason for this decrease in output power may be conjectured as hier due to the decreasing population of the upper laser level. The copper ion laser transition at 780 nm populated at the 5p level. The hollow cathode copper ion laser is operated in He and Ne mixture by electric discharge excitation and could be operated for more than 100 hours with only a 35% drop in the output power(2.8mW cw for 9.6cm active length).

• Journal of Welding and Joining
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• v.23 no.4
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• pp.53-58
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• 2005

We designed a weld monitoring system with UV and IR sensors using a embedded DSP controller for implementing a distribution system; running stand alone and communication with outside by industrial standard protocols. Also this system provided a USB port in order to be acquiring data in PC. The user interface program in PC visualized the IR and W data in time, frequency and state space. A correlation of IR and UV signals showed closely related to weld quality. A rapid change of geometry can be found through a moving average filter. And the average value of IR signal at an interval represented a welding width and depth. Through these results, we proposed a monitoring algorithm for a integer type DSP.

• 연구논문집
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• s.30
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• pp.43-56
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• 2000

N-IR spectroscopy technology is very useful. And, the technology has wide application range. In the range, we know that single beam type silica analyzer has some handicap. So we were studied Splitted beam type silica analyzer. This dissertation have been discuss about system structure, system fundamentals and performance test. At the test, we were study in the spectral interference of NH3. We know that existing system had some problem. It is structural frailties of single beam type. Therefore we were study for Splitted beam type structure. And we obtain a good result. We have $\pm$5% accuracy and 0.5 ppb level measuring range. But, we have a question. It is ppt level measuring technology by the laser beam spectroscopy.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.20-23
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• 2009

The efficacy improvement issues in a unit discharge cell have been approached from the structural considerations. The tested cell designs include (a) a coplanar type with annular auxiliary electrode buried in barrier ribs, (b) a coplanar type with split auxiliary electrodes also burred in barrier ribs and (c) a coaxial type with a floating electrode stacked on the base electrode. From spatiotemporally resolved optical images of near-IR emission taken by a gated-ICCD camera and relative VUV emission intensity estimated by laser absorption spectroscopy, the differences in the discharge and light emission performances of those three cell types have been compared and discussed.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.134-134
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• 2016

The effect of different thermal treatments on the sub-50 nm copper nanoparticles is examined in the aspects of chemical, electrical and surface morphology. The copper nanoparticles are chemically synthesized and fabricated for paste-type solution. Simple bar coating method is practiced as a deposition process to form copper thin film on a typical slide glass. Deposited copper thin films are annealed by two different routes: general tube furnace with 99.99 % Ar atmosphere and selective laser sintering process. The thermal behavior of the different thermal-treated copper thin films is compared by SEM, XRD, FT-IR and XPS analysis. In this study, the laser sintering process ensures low annealing temperature, fast working speed and ambient-accessible route. Moreover, the laser-sintered copper thin film shows good electrical property and enhanced chemical stability than conventional thermal annealing process. Consequently, the proposed laser sintering process can be compatible with plastic substrate for flexible applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.2
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• pp.149-154
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• 2022

In this paper, laser-induced fluorescence properties of four plastics were characterized through spectrometer analysis for real-time microplastic counting. Recently, environmental problems related to microplastics have emerged. In order to detect microplastics, analysis methods such as FT-IR and Raman are used. However, they have the disadvantages of being time-consuming and requiring a pretreatment process. In most plastic products on the market, 10% to 30% of plasticizers and reinforcing agents are added. Therefore, most microplastics present in seawater and freshwater emit fluorescence signals by 270 nm UV light source regardless of their type due to their molecular structure due to additives. Real-time microplastics counting is possible more easily by using the proposed laser-induced fluorescence detection method because of the fluorescence expression characteristic of 340 nm that appears due to the plasticizer of plastics.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.52-52
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• 2010

본 연구에서 우리는 HPHT 처리 전 FT-IR spectrometer를 이용한 사전분석을 통해 type Ia brown 다이아몬드를 IaA, IaB, IaAB (A>B), IaAB (A=B), IaAB (A$1700-1800^{\circ}C$, 5 GPa에서 다이아몬드가 흑연화 되지 않는 범위 하에 HPHT처리를 시행하였다. 자외선-가시광선 분광분석기(UV-Vis Spectrometer, Shimadzu UV 3101PC)를 사용하여 350~800 nm에서의 가시광선 범위를 0.1nm의 분해능으로 투과(Transmittance) 모드로 측정하였고, 퓨리에 변환 적외선 분광분석기(FT-IR spectrometer, Jasco-4100)을 사용하여 $400{\sim}6000cm^{-1}$의 범위에서 $4cm^{-1}$ 의 분해능으로 흡수(Absorption) 모드로 측정한 후 HPHT 처리 전후를 비교 분석하였다. 또한 광루미네선스(Photoluminescence) 분석은 325 nm He-Cd laser를 광원으로 한(PL, Spectra-pro 2150i, Spectra-pro 2300i micro-spectrometer) 및 532 nm green laser를 광원으로 한(PL, SAS 2000)를 사용하여 각각 350~600 nm, 550~1100 nm의 범위에서 0.1nm step으로 측정하여 HPHT 처리전과 후를 비교 분석하였다. HPHT처리 후 모든 시료는 N3 center (415.4 nm), H4 center (496.4nm) 및 platelet와 연관된 ($1363\;cm^{-1}$)의 peak가 감소하였고, H3 center (503.2 nm)와 G-band가 증가하는 경향을 나타내었다. 또한 HPHT 처리 시 질소의 B집합보다 A집합이 더 감소하는 경향을 나타내었으며, A 또는 B집합의 파괴에서 발생된 질소 원자에 의해 질소의 interstitial center (594 nm)가 증가함을 알 수 있었다. HPHT 처리 후 모든 시료는 (N-V)- center가 생성됨을 확인 할 수 있었다. 결론적으로 본 연구를 통해 HPHT 처리를 통해 다이아몬드 내에 존재하는 질소결합관련 상태의 변화를 확인할 수 있었다.

• Current Optics and Photonics
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• v.7 no.6
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• pp.738-744
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• 2023

Graphene-based saturable absorbers (SAs) are widely used as laser mode-lockers at various laser oscillators. In particular, transmission-type graphene-SAs with ultrabroad spectral coverage are typically manufactured on transparent substrates with low nonlinearity to minimize the effects on the oscillators. Here, we developed two types of transmitting graphene SAs based on CaF₂ and ZnSe. Using the graphene-SA based on CaF₂, a passively mode-locked mid-infrared Cr:ZnS laser delivers relatively long 540 fs pulses with a maximum output power of up to 760 mW. In the negative net cavity dispersion regime, the pulse width was not reduced further by inhomogeneous group delay dispersion (GDD) compensation. In the same laser cavity, we replaced only the graphene-SA based on CaF₂ with the SA based on ZnSe. Due to the additional self-phase modulation effect induced by the ZnSe substrate with high nonlinearity, the stably mode-locked Cr:ZnS laser produced Fourier transform-limited ~130 fs near 2,340 nm. In the stable single-pulse operation regime, average output powers up to 635 mW at 234 MHz repetition rates were achieved. To our knowledge, this is the first attempt to achieve shorter pulse widths from a polycrystalline Cr:ZnS laser by utilizing the graphene deposited on the substrate with high nonlinearity.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.85-87
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• 1990

Silicon nitride film was deposited on a silicon wafer using a laser CVD(LCVD) technique, which is based on direct photolysis of $SiH_4/NH_3$ gas mixture by ArF laser beam(${\lambda}=193\;nm$). The refractive index of deposited SiN film is 1.9 at the temperature of $300^{\circ}C$, pressure of 5 torr. The breakdown field strength of LCVD SiN film was 10MV/cm. In IR spectrum, the absorption peak of Si-H, N-H, and Si-N is detected and it is shown that hydrogen is included in SiN film. From analysis of absorption band. it is calculated that density of Si-H, N-H bond is higher than $5{\times}10^{22}cm^{-3}$. LCVD MIS capacitor and PECVD MIS capacitor have injection-type hysteresis but it is known that hysteresis loss of LCVD MIS capacitor is smaller than that of PECVD MIS capacitor. It means that Interface state density of LCVD capacitor is smaller than that of PECVD capacitor. In addition, the flatband voltage($V_{FB}$) of LCVD is smaller than that of PECVD capacitor. And it means that fixed charged density($Q_{FIX}$) of LCVD capacitor is smaller than that of PECVD MIS capacitor.

• Korean Journal of Optics and Photonics
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• v.6 no.2
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• pp.165-171
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• 1995

Infrared-Radio frequency double resonance (IRRFDR) and Infrared-Microwave double resonance (IRMWDR) spectroscopy have been used to probe a level of A symmetry for $CD_{3}$OH. Double resonance spectra of $CD_{3}$OH have been investigated over the range of 940 to 1020 $cm ^{-1}$ . Twenty K-type doublet transitions have been observed in both the radio frequency region, which covers 50 MHz to 1 GHz, and the microwave region, which covers 8 GHz to 12 GHz. The results propose new assignments of infrared (IR) absorption transitions and far-infrared (FIR) laser emission lines. These involve torsional excited levels and CO stretch states. Measurements of the A state splitting have permitted the determination of the asymmetry splitting parameters $S^{o}$(n, K) and $^{co}$ (n, K) for (n, K)=(0.3) and (1.3)