• 한국광학회:학술대회논문집
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• 한국광학회 1991년도 제6회 파동 및 레이저 학술발표회 Prodeedings of 6th Conference on Waves and Lasers
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• pp.66-68
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• 1991

색소레이저의 효율과 출력 증가를 위한 연구에서 보다 강력한 펌핑 광원의 개발에 주로 많은 관심을 기울이고 있다. 그러나 본 연구에서는 펌핑광의 스펙트럼 전환을 이용하여 청록색레이저의 효율과 출력에너지를 증가 시켰다. 레이저 색소 Coumarin 503을 전환색소 BBQ와 혼합하므로 160% 이상의 청록색레이저의 출력에너지 증가와 61%의 구배 효율 증가를 얻었다.

• 한국재료학회지
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• 제20권12호
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• pp.649-653
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• 2010

In this paper, double texturization of multi crystalline silicon solar cells was studied with laser and reactive ion etching (RIE). In the case of multi crystalline silicon wafers, chemical etching has problems in producing a uniform surface texture. Thus various etching methods such as laser and dry texturization have been studied for multi crystalline silicon wafers. In this study, laser texturization with an Nd:$YVO_4$ green laser was performed first to get the proper hole spacing and $300{\mu}m$ was found to be the most proper value. Laser texturization on crystalline silicon wafers was followed by damage removal in acid solution and RIE to achieve double texturization. This study showed that double texturization on multi crystalline silicon wafers with laser firing and RIE resulted in lower reflectance, higher quantum yield and better efficiency than that process without RIE. However, RIE formed sharp structures on the silicon wafer surfaces, which resulted in 0.8% decrease of fill factor at solar cell characterization. While chemical etching makes it difficult to obtain a uniform surface texture for multi crystalline silicon solar cells, the process of double texturization with laser and RIE yields a uniform surface structure, diminished reflectance, and improved efficiency. This finding lays the foundation for the study of low-cost, high efficiency multi crystalline silicon solar cells.

• 한국광학회지
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• 제2권4호
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• pp.179-185
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• 1991

적외선 광원으로 $CO_2$ 레이저를 사용하였고 광속을 2.5 cm의 직경으로 확대하여 Twyman-Green 간섭계를 구성하였다. 각종 렌즈는 Ge 렌즈로, 광속분리기는 ZnSe 평행판으로 택하였다. Pyro-electric vidicon camera에 의해 CRT monitor에 간섭무늬를 제시하며 image card에 의해 digitize되고 PC로 강도분포가 입력되어 data처리된다. 여기서, 적외선 간섭무늬는 thermal paper 상에 기록하였다. 가시영역에서는 He-Nefp이저를 광원으로 하고 CCD 카메라로 검출하여 CRT monitor에 제시하였다. 파면수차함수, PSF, OTF가 계산되어 3차원 그래프로 제시되며 프린트 된다.

• 센서학회지
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• 제28권4호
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• pp.262-265
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• 2019

The effect of inter-band transition on surface plasmon resonance in gold thin film was investigated. We induced localized inter-band transition in the film by using incident light on its surface from a green laser (532 nm) source, and the surface plasmon resonance for inter-band transition was investigated at different wavelengths. It was determined that the reflectivity of blue light (450 nm) was significantly reduced in the region where the green laser was incident. We demonstrated that this decrease is mainly due to the coupling between the blue light and the surface plasmon resonance of excited electrons in higher energy states, based on experimental results for the incident and polarization angle-dependent reflectivity of the blue light.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.290.1-290.1
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• 2016

Grapehen, a single atomic layer of graphite, has been in the spotlight and researched in vaious fields, because its fine mechanical, electrical properties, flexibility and transparence. Synthesis methods for large-area graphene such as chemical vaper deposition (CVD) and mechanical, chemical exfoliation have been reported. In particular, chemical exfoliation method receive attention due to low cost process. Chemical exfoliation method require reduction of graphene oxide in the process of exfoliation such as chemical reduction by strong reductant, thermal reduction on high temperature, and optical reduction via ultraviolet light exposure. Among these reduction methods, optical reduction is free from damage by strong reductant and high temperature. However, optical reduction is economically infeasible because the high cost of short-wavelength ultraviolet light sorce. In this paper, we make graphene-oxide and lanthanoid ion mixture aqueous solution which has highly optical absorbency in selective wevelength region. Sequentially, we synthesize reduced graphene oxide (RGO) using the solution and visible laser beam. Concretely, graphene oxide is made by modified hummer's method and mix with 1 ml each ultraviolet ray absorbent Gd3+ ion, Green laser absorbent Tb3+ ion, Red laser absorbent Eu3+ ion. After that, we revivify graphene oxide by laser exposure of 300 ~ 800 nm layser 1mW/cm2 +. We demonstrate reproducibility and repeatability of RGO through FT-IR, UV-VIS, Low temperature PL, SEM, XPS and electrical measurement.

• 한국컴퓨터산업학회논문지
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• 제2권4호
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• pp.565-572
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• 2001

최근 고체 레이저 출력측에 비선형 광학재료를 설치하여 적외선에서 자외선에 이르기까지 넓은 대역의 파장을 가진 레이저광이 요구된다. 비선형 광학소자는 고조파발생기와 파라메터 발생기와 같은 레이저원을 이용한 주파수 전 영역까지 확장 할 수가 있다. 주파수 변환은 고전력 레이저를 이용한 확장기술에 많이 이용하고있다. 새로운 각 주파수 대역에서 광학 매개체의 비선형 광학의 응답 등을 이용할 수가 있다. 이러한 과정들은 자외선영역에서 적외선까지 고전력 방사발생을 이용할 수가 있다. 광학 파라메터발생기와 증폭기는 저주파수에서 2가지 파장 등을 발생한다. 싱글 주파수원으로부터 발생하여 몇몇의 경우에는 가시광선 영역에서 거의 자외선 영역까지 이용할 수가 있다. 결과적으로 녹색광을 얻기 위해서, 펄스형Nd:YAG 레이저는 다단펄스 포밍회로를 이용하였고 비선형광학(KTP)소자를 채택하여 적용하였다. 따라서 본 연구에서는 펄스 중첩법을 이용하여 기본파로서 직접 설계 제작 후 SHG 장치를 장착하여 녹색광을 얻고 각 중첩 메쉬에 같은 에너지를 인가했을 때의 레이저 출력과 녹색광 출력간의 상관관계와 메쉬 수에 따른 변환효율을 조사하였다.

• Physical Therapy Rehabilitation Science
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• 제3권1호
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• pp.20-26
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• 2014

Objective: The low level lasers currently in the market vary in wavelength, dosage, and frequency. These devices are used with much different clinical pathology. Most notably, some studies claim that wounds heal faster with low level laser therapy due to the fact that bacteria commonly found in wounds are killed by laser light. Systemic and meta-analysis studies found the difficulty of comparison of numerous research studies because of differences in the intensities and frequencies of low level laser treatment (LLLT). The purpose of this study was to determine the effectiveness of LLLT on controlling bacterial growth. Design: Cross-sectional study. Methods: Variables included LLLT dosage and wavelength on 3 bacteria commonly seen in wounds, strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were used on commercially available 5.0-cm agar plates. Blue, green, and red, ultraviolet (UV) and infrared laser light sources were adjusted to either low or high intensity settings. Five Petri dishes at a time were placed directly beneath laser light sources with the exception of UV which was placed six inches below the suspended light and infrared which was placed directly on top of the Petri dish lid. Each group of five Petri dishes was irradiated for 15 minutes. Results: The results showed no effect of any of 9 different LLLT intensities or colors on bacteria growth compared to sham light. Conclusions: At least for claims of bacterial growth inhibition with LLLT, no support for this claim can be found here.

• 한국산업융합학회 논문집
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• 제25권3호
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• pp.365-378
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• 2022

Complete blood cell count(CBC) is a technique that counts leukocytes for each type of blood cell being analyzed. The principle is that laser is incident to ex vivo flowing leukocytes in a microcapillary tube and scattered light occurs by laser and leukocytes. By collecting the scattered light, we can count the types of cells because different cells generate different light-scattering patterns. However, the technique has an intrinsic limitation, scattering pattern is shown in a wide range region in the resulting, which makes it difficult to accurate analyze and use fluorescent dyes. To overcome this limitation, a new design of CBC with a dual laser, which irradiates with orthogonal angles for collecting quad-scattering information was proposed. Before development, the scattering difference depending on wavelength must be investigated to only catch up to the scattered signal by angles. Some studies, which focused on simple particles, have been conducted to theoretically and experimentally investigate different scatterings by wavelength. In this study, we propose an optical system for measuring scattered light and investigate a complex particle. As a result, the green laser made strong scattering signals in both the forward and side direction: 10% and 30%, respectively.

• 대한소아치과학회지
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• 제47권4호
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• pp.446-453
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• 2020

이 연구의 목적은 Indocyanine Green(ICG)과 근적외선(Near Infrared, NIR) 다이오드 레이저가 Streptococcus mutans 세균막에 미치는 효과를 ICG 용액의 농도에 따라 평가하는 것이었다. Hydroxyapatite disk에 S. mutans 세균막을 형성하여 멸균 증류수에 용해시킨 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 mg/mL의 ICG 용액과 300 mW의 출력, 808 nm의 파장을 가지는 NIR 다이오드 레이저를 적용하였다. 모든 표본은 공초점 레이저 주사 현미경(Confocal Laser Scanning Microscopy, CLSM)을 이용하여 관찰하였다. 또한 1채널 열전대 온도계와 Thermocouple을 이용하여 광조사 시에 ICG 용액의 농도에 따른 세균막 표면의 온도 변화를 함께 측정하였다. 대조군과 비교 시에 ICG 용액 만을 도포한 군에서는 3.0, 4.0, 5.0 mg/mL의 농도에서, 그리고 ICG 용액의 도포와 광조사를 함께 시행한 군에서는 1.0, 2.0, 3.0, 4.0, 5.0 mg/mL의 농도에서 통계적으로 유의한 세균 수의 감소가 관찰되었다. 용액의 농도에 따른 온도 증가량은 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 mg/mL의 ICG 용액에서 각각 9.53℃, 10.43℃, 11.4℃, 12.1℃, 12.67℃, 13.63℃ 이었다. 즉, ICG 용액의 농도가 3.0 mg/mL이면 그 자체로도 S. mutans 세균막을 억제할 수는 있으나, NIR 다이오드 레이저를 함께 사용하면 주변 조직 손상의 우려 없이 더 효율적인 항균 작용을 나타낼 수 있다. 따라서, 이번 연구는 새로운 치아 우식증 예방법으로 ICG와 NIR 다이오드 레이저의 임상적 적용의 가능성을 제시한다.

• Journal of Ceramic Processing Research
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• 제20권2호
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• pp.158-163
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• 2019

Er3+/Yb3+-codoped NaLa(MoO4)2 colloidal nanocrystals were synthesized by pulsed laser ablations in de-ionized water and sodium dodecyl sulfate (NaC12H25SO4, SDS) aqueous solution for up-conversion (UC) luminescence bio-labeling applications. The influences of the SDS molecules on the crystallinities, crystal morphologies, crystallite sizes, and UC luminescence properties of the prepared Er3+/Yb3+-codoped NaLa(MoO4)2 colloidal nanocrystals were investigated in detail. Under a 980-nm excitation, the Er3+/Yb3+-codoped nanocolloidal NaLa(MoO4)2 suspension exhibited a weak red emission near 670 nm and strong green UC emissions at 530 and 550 nm, corresponding to the intra 4f transitions of Er3+ (4F9/2, 2H11/2, 4S3/2) → Er3+ (4I15/2). When the SDS solution was used, a smaller average crystallite size, narrower size distribution, and enhanced UC luminescence were observed. These characteristics were attributed to the amphoteric SDS molecules attached to the positively charged Er3+/Yb3+-codoped NaLa(MoO4)2 colloidal nanocrystals, effectively occupying the oxygen defect on their surfaces. The Er3+/Yb3+-codoped nanocrystalline NaLa(MoO4)2 suspension prepared in the SDS solution exhibited a remarkably strong green emission visible to the naked eyes.