Pub Date : 2020-01-01DOI: 10.3807/KJOP.2020.31.5.205
Kyung-min Hong, N. Park
In the performance of a wind turbine system, the blades play a vital role. However, they are susceptible to damage arising from complex and irregular loading (which may even cause catastrophic collapse), and they are expensive to maintain. Therefore, it is very important both to find defects after blade manufacturing is completed and to find damage after the blade is used for a certain period of time. This study provides a new perspective for the detection of internal defects in glass-fiber-and carbon-fiber-reinforced panels, which are used as the main materials in wind turbine blades. A gap or fracture between fiber-reinforced materials, which may occur during blade manufacturing or operation, is simulated by drilling a hole 5 mm in diameter in the middle layer of the laminated material. Then, a digital-image-correlation (DIC) method is used to detect internal defects in the blade. Tensile load is applied to the fabricated specimen using a tensile tester, and the generated changes are recorded and analyzed with the DIC system. In the glass-fiber-reinforced laminated specimen, internal defects were detected from a strain value of 5% until the end of the experiment, while in the case of the carbon-fiber-reinforced laminated specimen, internal defects were detected from 1% onward. It was proved using the DIC system that the defect was detected as a certain level of strain difference developed around the internal defects, according to the material properties.
{"title":"Development of Digital-Image-Correlation Technique for Detecting Internal Defects in Simulated Specimens of Wind Turbine Blades","authors":"Kyung-min Hong, N. Park","doi":"10.3807/KJOP.2020.31.5.205","DOIUrl":"https://doi.org/10.3807/KJOP.2020.31.5.205","url":null,"abstract":"In the performance of a wind turbine system, the blades play a vital role. However, they are susceptible to damage arising from complex and irregular loading (which may even cause catastrophic collapse), and they are expensive to maintain. Therefore, it is very important both to find defects after blade manufacturing is completed and to find damage after the blade is used for a certain period of time. This study provides a new perspective for the detection of internal defects in glass-fiber-and carbon-fiber-reinforced panels, which are used as the main materials in wind turbine blades. A gap or fracture between fiber-reinforced materials, which may occur during blade manufacturing or operation, is simulated by drilling a hole 5 mm in diameter in the middle layer of the laminated material. Then, a digital-image-correlation (DIC) method is used to detect internal defects in the blade. Tensile load is applied to the fabricated specimen using a tensile tester, and the generated changes are recorded and analyzed with the DIC system. In the glass-fiber-reinforced laminated specimen, internal defects were detected from a strain value of 5% until the end of the experiment, while in the case of the carbon-fiber-reinforced laminated specimen, internal defects were detected from 1% onward. It was proved using the DIC system that the defect was detected as a certain level of strain difference developed around the internal defects, according to the material properties.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"31 1","pages":"205-212"},"PeriodicalIF":0.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70162108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.3807/KJOP.2020.31.2.096
Hyunuk Park, J. Jo
광축을 기준으로 시야각이 180도를 넘어가는 영상을 한 번 에 결상하는 단일 광학계를 전방위 광학계라고 한다. 이러 한 시야각 범위 안에 있는 물체들이 광축상에 놓여져 있는 평면의 CCD나 CMOS에 결상이 되면 심하게 왜곡된 파노라 마 영상이 보여진다. 본 논문에서 제한하는 전방위 광학계는 광축을 기준으로 일정 부분까지의 시야각이 차폐되는 전방 위 광학계이다. 그러므로 본 전방위 광학계에서 획득된 영상 은 중심 부분의 영상이 없이 심하게 왜곡된 도넛 형태의 상 이다. 이것을 기반으로 광축의 수직 방향을 기준으로 잡아 서 그 기준에서 일정한 시야각을 360도로 볼 수 있는 광학계 를 전방위 광학계로 정의한다. 이러한 전방위 광학계는 렌 즈나 거울을 사용하여 광각의 이미지를 보는 특징을 갖는다. Design and Performance of a Catadioptric Omnidirectional Zoom Optical System Using a Hybrid Lens for Visible Light
以光轴为标准，一次将视野角超过180度的影像挂在一起的单一光学界被称为全方位光学界。如果在这样的视野范围内的物体被放在光轴上的平面的CCD或CMOS结伤，就会出现严重扭曲的帕诺拉玛影像。本论文限制的全方位光学界是以光轴为标准，遮挡一定部分视野角的全方位光学界。因此，从全方位光学界获得的影像是没有中心部分影像的严重歪曲的甜甜圈形态的像。以此为基础，以光轴的垂直方向为标准，在其标准中可以360度看到一定视野角的光学界被定义为全方位光学界。这种全方位光学界具有使用透镜或镜子看光角图像的特点。设计与性能a Catadioptric Omnidirectional Zoom Optical System Using a Hybrid Lens for Visible Light
{"title":"Design and Performance of a Catadioptric Omnidirectional Zoom Optical System Using a Hybrid Lens for Visible Light","authors":"Hyunuk Park, J. Jo","doi":"10.3807/KJOP.2020.31.2.096","DOIUrl":"https://doi.org/10.3807/KJOP.2020.31.2.096","url":null,"abstract":"광축을 기준으로 시야각이 180도를 넘어가는 영상을 한 번 에 결상하는 단일 광학계를 전방위 광학계라고 한다. 이러 한 시야각 범위 안에 있는 물체들이 광축상에 놓여져 있는 평면의 CCD나 CMOS에 결상이 되면 심하게 왜곡된 파노라 마 영상이 보여진다. 본 논문에서 제한하는 전방위 광학계는 광축을 기준으로 일정 부분까지의 시야각이 차폐되는 전방 위 광학계이다. 그러므로 본 전방위 광학계에서 획득된 영상 은 중심 부분의 영상이 없이 심하게 왜곡된 도넛 형태의 상 이다. 이것을 기반으로 광축의 수직 방향을 기준으로 잡아 서 그 기준에서 일정한 시야각을 360도로 볼 수 있는 광학계 를 전방위 광학계로 정의한다. 이러한 전방위 광학계는 렌 즈나 거울을 사용하여 광각의 이미지를 보는 특징을 갖는다. Design and Performance of a Catadioptric Omnidirectional Zoom Optical System Using a Hybrid Lens for Visible Light","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"1 1","pages":"96-104"},"PeriodicalIF":0.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70161172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.3807/KJOP.2020.31.3.148
Ki Won Jeong, Y. Do
컬러필터는 빛에서 인간이 인식할 수 있는 가시광선 영역 을 분류하는 특성을 가지고 있으며 이러한 특성은 액정 디스 플레이, 이미지 센서 등 이미징 디바이스 분야에 사용되고 있다. 하지만 일반적으로 널리 사용되고 있는 컬러필터는 안 료와 염료를 사용하여 제작되기 때문에 빛, 열 및 화학물질 노출에 의해 색이 변하거나 필터성능이 저하된다. 이런 내구 성 문제는 디스플레이의 수명에 직접적인 영향을 끼친다. 더 불어 일반적인 컬러필터 제작에 사용되는 포토 리소그래피, 잉크젯 프린팅은 제작할 수 있는 화소의 크기에 한계가 있기 때문에 두께가 얇아지고 화소의 크기가 작아지는 이미징 디 바이스의 동향에 적합하지 않다. 이와 같은 일반적인 컬러필터의 문제점을 보완하기 위해 Polyperiodic-hole-array Plasmonic Color Filter for Minimizing the Effect of Angle of Incidence
彩色过滤器具有将人类在光线中能够识别的可视光线领域进行分类的特性，这一特性被用于液晶显示器、图像传感器等成像设备领域。但是，一般广泛使用的彩色过滤器使用眼药水和染料制作而成，因此会因光、热及化学物质的暴露而变色或降低过滤性能。这种耐久性问题直接影响显示屏的寿命。更夸张的是，一般彩色过滤器制作时使用的图像处理、喷墨打印，由于所能制作的像素大小有限，不适合厚度变薄、像素变小的影像设备的动向。Polyperiodic-hole-array Plasmonic Color Filter for Minimizing the Effect of Angle of Incidence
{"title":"Polyperiodic-hole-array Plasmonic Color Filter for Minimizing the Effect of Angle of Incidence","authors":"Ki Won Jeong, Y. Do","doi":"10.3807/KJOP.2020.31.3.148","DOIUrl":"https://doi.org/10.3807/KJOP.2020.31.3.148","url":null,"abstract":"컬러필터는 빛에서 인간이 인식할 수 있는 가시광선 영역 을 분류하는 특성을 가지고 있으며 이러한 특성은 액정 디스 플레이, 이미지 센서 등 이미징 디바이스 분야에 사용되고 있다. 하지만 일반적으로 널리 사용되고 있는 컬러필터는 안 료와 염료를 사용하여 제작되기 때문에 빛, 열 및 화학물질 노출에 의해 색이 변하거나 필터성능이 저하된다. 이런 내구 성 문제는 디스플레이의 수명에 직접적인 영향을 끼친다. 더 불어 일반적인 컬러필터 제작에 사용되는 포토 리소그래피, 잉크젯 프린팅은 제작할 수 있는 화소의 크기에 한계가 있기 때문에 두께가 얇아지고 화소의 크기가 작아지는 이미징 디 바이스의 동향에 적합하지 않다. 이와 같은 일반적인 컬러필터의 문제점을 보완하기 위해 Polyperiodic-hole-array Plasmonic Color Filter for Minimizing the Effect of Angle of Incidence","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"31 1","pages":"148-154"},"PeriodicalIF":0.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70160932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.3807/KJOP.2020.31.1.031
H. Ryu
테라헤르츠파는 전자기파 스펙트럼에서 마이크로파와 원 적외선의 중간 영역에 해당하는 0.1~10 THz 대역의 주파수 자원으로, 마이크로파 생성 기술과 광파 생성 기술 모두 적 용하기 어려워 오랜 기간 동안 미개발되어 ‘테라헤르츠 갭 (terahertz gap)’으로 불리어 왔다. 이러한, 테라헤르츠파는 전 파의 투과성과 광파의 직진성을 동시에 가지고 있고, 분자 운동의 진동주파수 영역이 테라헤르츠파 주파수 대역에 존 재하므로 물질의 성분 분석에 적합하여 물질의 물성, 분자, 생명 연구 등을 위한 분광 시스템, 이미징 시스템, 그리고 넓 은 주파수 대역폭을 이용한 초고속 무선 통신 시스템 등 다 양한 분야에 응용이 가능하여 많은 연구가 진행되고 있다 . 그러나 실질적으로 테라헤르츠 대역에서 사용 가능한 소자의 개발은 자연계 물질의 전기적, 자기적 특성이 테라헤 르츠파 주파수 대역에서 소자로 활용되기에 적합하지 않아 마이크로파나 광파 대역에 비교하여 매우 부족한 상황이다. 그러므로 인공적으로 전기/자기적 특성을 제어할 수 있는 메 타물질을 테라헤르츠파의 소자로서 활용하는 연구가 많은 관심을 받아 왔다. 메타물질은 관심 파장보다 작은 크기의 유닛 셀을 금속이나 유전체 물질을 이용하여 형성하고 주기 적으로 배열하여 전체 구조를 균일한 물질로 인식하도록 인 Band-switchable Terahertz Metamaterial Based on an Etched VO2 Thin Film
terra赫兹派在电磁光谱的微波和红外线中间领域相当于0.1 ~ 10 thz替身的频率资源,生成微波和光波生成技术都很难利用敌人长时间未开发了“terra赫兹(terahertz gap)”之称。mb,这种赫兹称前派的穿透性和光波的直行同时拥有,分子运动的振动频率领域terra赫兹频率杆存在,物质的成分,适合物质的物性分析、分子、生命研究等为分光系统,成像系统,它还可以应用于多种领域，如利用宽频带宽的超高速无线通信系统等。但实际上，在太赫兹频带中可以使用的元件的开发，由于自然界物质的电、磁特性不适合在太赫兹波频带中用作元件，与微波或光波频带相比是非常不足的状况。因此，将人工控制电/磁特性的甲烷物质作为太赫兹波元件的研究备受关注。元物质利用金属或遗传物质形成比关心波长更小的单元单元，并周期性排列，使整体结构被识别为均匀物质的Band-switchable Terahertz Metamaterial Based on an Etched VO2 Thin Film
{"title":"Band-switchable Terahertz Metamaterial Based on an Etched VO 2 Thin Film","authors":"H. Ryu","doi":"10.3807/KJOP.2020.31.1.031","DOIUrl":"https://doi.org/10.3807/KJOP.2020.31.1.031","url":null,"abstract":"테라헤르츠파는 전자기파 스펙트럼에서 마이크로파와 원 적외선의 중간 영역에 해당하는 0.1~10 THz 대역의 주파수 자원으로, 마이크로파 생성 기술과 광파 생성 기술 모두 적 용하기 어려워 오랜 기간 동안 미개발되어 ‘테라헤르츠 갭 (terahertz gap)’으로 불리어 왔다. 이러한, 테라헤르츠파는 전 파의 투과성과 광파의 직진성을 동시에 가지고 있고, 분자 운동의 진동주파수 영역이 테라헤르츠파 주파수 대역에 존 재하므로 물질의 성분 분석에 적합하여 물질의 물성, 분자, 생명 연구 등을 위한 분광 시스템, 이미징 시스템, 그리고 넓 은 주파수 대역폭을 이용한 초고속 무선 통신 시스템 등 다 양한 분야에 응용이 가능하여 많은 연구가 진행되고 있다 . 그러나 실질적으로 테라헤르츠 대역에서 사용 가능한 소자의 개발은 자연계 물질의 전기적, 자기적 특성이 테라헤 르츠파 주파수 대역에서 소자로 활용되기에 적합하지 않아 마이크로파나 광파 대역에 비교하여 매우 부족한 상황이다. 그러므로 인공적으로 전기/자기적 특성을 제어할 수 있는 메 타물질을 테라헤르츠파의 소자로서 활용하는 연구가 많은 관심을 받아 왔다. 메타물질은 관심 파장보다 작은 크기의 유닛 셀을 금속이나 유전체 물질을 이용하여 형성하고 주기 적으로 배열하여 전체 구조를 균일한 물질로 인식하도록 인 Band-switchable Terahertz Metamaterial Based on an Etched VO2 Thin Film","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"31 1","pages":"31-36"},"PeriodicalIF":0.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70160731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.3807/KJOP.2020.31.3.125
Yang Jun-Ho, Yoh, Jai-Ick
An innovative method for separating overlapping latent fingerprints, using laser-induced plasma spectroscopy (LIPS) combined with multivariate analysis, is reported in the current study. LIPS provides the capabilities of real-time analysis and high-speed scanning, as well as data regarding the chemical components of overlapping fingerprints. These spectra provide valuable chemical information for the forensic classification and reconstruction of overlapping latent fingerprints, by applying appropriate multivariate analysis. This study utilizes principal-component analysis (PCA) and partial-least-squares (PLS) techniques for the basis classification of four types of fingerprints from the LIPS spectra. The proposed method is successfully demonstrated through a classification example of four distinct latent fingerprints, using discrimination such as soft independent modeling of class analogy (SIMCA) and partial-least-squares discriminant analysis (PLS-DA). This demonstration develops an accuracy of more than 85% and is proven to be sufficiently robust. In addition, by laser-scanning analysis at a spatial interval of 125 μm, the overlapping fingerprints were separated as two-dimensional forms.
{"title":"Forensic Classification of Latent Fingerprints Applying Laser-induced Plasma Spectroscopy Combined with Chemometric Methods","authors":"Yang Jun-Ho, Yoh, Jai-Ick","doi":"10.3807/KJOP.2020.31.3.125","DOIUrl":"https://doi.org/10.3807/KJOP.2020.31.3.125","url":null,"abstract":"An innovative method for separating overlapping latent fingerprints, using laser-induced plasma spectroscopy (LIPS) combined with multivariate analysis, is reported in the current study. LIPS provides the capabilities of real-time analysis and high-speed scanning, as well as data regarding the chemical components of overlapping fingerprints. These spectra provide valuable chemical information for the forensic classification and reconstruction of overlapping latent fingerprints, by applying appropriate multivariate analysis. This study utilizes principal-component analysis (PCA) and partial-least-squares (PLS) techniques for the basis classification of four types of fingerprints from the LIPS spectra. The proposed method is successfully demonstrated through a classification example of four distinct latent fingerprints, using discrimination such as soft independent modeling of class analogy (SIMCA) and partial-least-squares discriminant analysis (PLS-DA). This demonstration develops an accuracy of more than 85% and is proven to be sufficiently robust. In addition, by laser-scanning analysis at a spatial interval of 125 μm, the overlapping fingerprints were separated as two-dimensional forms.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"31 1","pages":"125-133"},"PeriodicalIF":0.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70161366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study we report a wet-etching-based fabrication method for adiabatic optical-fiber tapers (OFTs), and describe their adiabaticity and HE11 mode evolution at a wavelength of 1550 nm. The profile of the fabricated system satisfies the adiabaticity properties well, and the far-field pattern from the etched OFT shows that the fundamental HE11 mode is maintained without a higher-order mode coupling throughout the tapers. In addition, the measured far-field pattern agrees well with the simulated result. The proposed adiabatic OFTs can be applied to a number of photonic applications, especially fiber-chip packages. Based on the fabricated adiabatic OFT structures, the optical transmission to the inversely tapered silicon waveguide shows large spatialdimensional tolerances for 1 dB excess loss of ~60 μm (silicon waveguide angle of 1°) and insertion loss of less than 0.4 dB (silicon waveguide angle of 4°), from the numerical simulation. The proposed adiabatic coupler shows the ultrabroadband coupling efficiency over the Oand C-bands.
{"title":"Adiabatic Optical-fiber Tapers for Efficient Light Coupling between Silicon Waveguides and Optical Fibers","authors":"Gyeongho Son, Jiwon Choi, Jeong Youngjae, Kyoungsik Yu","doi":"10.3807/KJOP.2020.31.5.213","DOIUrl":"https://doi.org/10.3807/KJOP.2020.31.5.213","url":null,"abstract":"In this study we report a wet-etching-based fabrication method for adiabatic optical-fiber tapers (OFTs), and describe their adiabaticity and HE11 mode evolution at a wavelength of 1550 nm. The profile of the fabricated system satisfies the adiabaticity properties well, and the far-field pattern from the etched OFT shows that the fundamental HE11 mode is maintained without a higher-order mode coupling throughout the tapers. In addition, the measured far-field pattern agrees well with the simulated result. The proposed adiabatic OFTs can be applied to a number of photonic applications, especially fiber-chip packages. Based on the fabricated adiabatic OFT structures, the optical transmission to the inversely tapered silicon waveguide shows large spatialdimensional tolerances for 1 dB excess loss of ~60 μm (silicon waveguide angle of 1°) and insertion loss of less than 0.4 dB (silicon waveguide angle of 4°), from the numerical simulation. The proposed adiabatic coupler shows the ultrabroadband coupling efficiency over the Oand C-bands.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"31 1","pages":"213-217"},"PeriodicalIF":0.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70162262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.3807/KJOP.2020.31.5.218
Hwanseong Jeong, K. Lee, Junsu Lee, Dongjoon Kim, Jeonghwan Lee, Minsik Jo
최근 들어 고출력 광섬유 레이저에 대한 연구가 활발히 이 루어지고 있으며 그 결과로 주 공진기 파워 증폭기(master oscillator power amplifier, MOPA) 타입의 수 kW 급 광섬유 레이저들이 보고되고 있다. 고출력 광섬유 레이저 구성 시 모든 부품이 광섬유로 이루어진 광섬유 레이저는 높은 빔 품질 특성 및 우수한 출력 안정성을 가지고 있다. 이러한 특 성을 이용하여 광섬유 레이저는 기초과학, 재료 가공 및 국 방 등 많은 분야에서 응용되고 있으며 응용 분야가 확대됨에 따라 더 높은 레이저 출력에 대한 요구가 증가하고 있다. 이에 수십 kW 급 이상의 고출력 고품질 광섬유 레이저 출력 High-beam-quality 2-kW-class Spectrally Combined Laser Using Narrow-linewidth Ytterbium-doped Polarization-maintaining Fiber Amplifiers
最近，对高输出光纤激光的研究越来越活跃，其结果是主共振器功率放大器(master oscillator power amplifier, MOPA)类型的数千瓦级光纤激光。高输出光纤激光构成时，所有部件由光纤组成的光纤激光具有高光束品质特性和优秀的输出稳定性。利用这一特点，光纤激光在基础科学，材料加工及国防等许多领域得到了应用，随着应用领域的扩大，对更高激光输出的要求也在增加。数十千瓦级以上高输出高品质光纤激光输出High-beam-quality 2-kW-class Spectrally Combined Laser Using Narrow-linewidth Ytterbium-doped Polarization-maintaining Fiber Amplifiers
{"title":"High-beam-quality 2-kW-class Spectrally Combined Laser Using Narrow-linewidth Ytterbium-doped Polarization-maintaining Fiber Amplifiers","authors":"Hwanseong Jeong, K. Lee, Junsu Lee, Dongjoon Kim, Jeonghwan Lee, Minsik Jo","doi":"10.3807/KJOP.2020.31.5.218","DOIUrl":"https://doi.org/10.3807/KJOP.2020.31.5.218","url":null,"abstract":"최근 들어 고출력 광섬유 레이저에 대한 연구가 활발히 이 루어지고 있으며 그 결과로 주 공진기 파워 증폭기(master oscillator power amplifier, MOPA) 타입의 수 kW 급 광섬유 레이저들이 보고되고 있다. 고출력 광섬유 레이저 구성 시 모든 부품이 광섬유로 이루어진 광섬유 레이저는 높은 빔 품질 특성 및 우수한 출력 안정성을 가지고 있다. 이러한 특 성을 이용하여 광섬유 레이저는 기초과학, 재료 가공 및 국 방 등 많은 분야에서 응용되고 있으며 응용 분야가 확대됨에 따라 더 높은 레이저 출력에 대한 요구가 증가하고 있다. 이에 수십 kW 급 이상의 고출력 고품질 광섬유 레이저 출력 High-beam-quality 2-kW-class Spectrally Combined Laser Using Narrow-linewidth Ytterbium-doped Polarization-maintaining Fiber Amplifiers","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"31 1","pages":"218-222"},"PeriodicalIF":0.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70162301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.3807/KJOP.2020.31.1.007
Junsu Lee, K. Lee, Hwanseong Jeong, Dong J. Kim, Jung Hwan Lee, Minsik Jo
In this paper, we experimentally investigate the fiber fuse in single-mode 2-kW-class high-power fiber amplifiers, depending on the cooling method at the splicing point. We measured the temperature of the splicing point between the pump-signal combiner and gain fiber as a function of laser output power. The temperature of the splicing point increased from 20 to 32°C with a slope of 0.01°C/W, up to 1.2 kW of laser output power. At higher powers the temperature of the splicing point increased dramatically, with a slope of 0.08°C/W. After that, the fiber amplifier was destroyed during operation at 1.96 kW of output power by fiber fuse. The bullet shape, a common feature of fiber fuse, was observed in the damaged passive fiber core of the pump-signal combiner. Later, we adopted an improved water-cooled cold plate to increase the cooling efficiency at the splicing point, and investigated the laser output power. The temperature at the splicing point was 35.8°C with a temperature-rise slope of 0.007°C/W at the maximum output power of 2.05 kW. The beam quality M2 was measured to be less than 1.3, and the output beam’s profile was a stable Gaussian shape. Finally, neither fiber fuse nor mode instability was observed in the fiber amplifier at the maximum output power of 2.05 kW.
{"title":"A Study of the Fiber Fuse in Single-mode 2-kW-class High-power Fiber Amplifiers","authors":"Junsu Lee, K. Lee, Hwanseong Jeong, Dong J. Kim, Jung Hwan Lee, Minsik Jo","doi":"10.3807/KJOP.2020.31.1.007","DOIUrl":"https://doi.org/10.3807/KJOP.2020.31.1.007","url":null,"abstract":"In this paper, we experimentally investigate the fiber fuse in single-mode 2-kW-class high-power fiber amplifiers, depending on the cooling method at the splicing point. We measured the temperature of the splicing point between the pump-signal combiner and gain fiber as a function of laser output power. The temperature of the splicing point increased from 20 to 32°C with a slope of 0.01°C/W, up to 1.2 kW of laser output power. At higher powers the temperature of the splicing point increased dramatically, with a slope of 0.08°C/W. After that, the fiber amplifier was destroyed during operation at 1.96 kW of output power by fiber fuse. The bullet shape, a common feature of fiber fuse, was observed in the damaged passive fiber core of the pump-signal combiner. Later, we adopted an improved water-cooled cold plate to increase the cooling efficiency at the splicing point, and investigated the laser output power. The temperature at the splicing point was 35.8°C with a temperature-rise slope of 0.007°C/W at the maximum output power of 2.05 kW. The beam quality M2 was measured to be less than 1.3, and the output beam’s profile was a stable Gaussian shape. Finally, neither fiber fuse nor mode instability was observed in the fiber amplifier at the maximum output power of 2.05 kW.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"31 1","pages":"7-12"},"PeriodicalIF":0.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70160599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.3807/KJOP.2020.31.4.176
Hwan-young Choi
The possibility of replacing the condensing-prism film used in conventional backlight units with a light-guide plate engraved with a submicrometer-periodic diffraction grating was investigated. The optimal period for the diffraction grating was determined through simulation and experiment, and the transmission-mode efficiency of the diffraction grating was calculated in terms of the polar angle and azimuthal angle of the incident light. In addition, the effects of the two methods of optimizing the polar angle and the directional angle were compared by simulation, by suggesting the shape and configuration of the light-guide plate, so that more light could be extracted by diffraction. By using a ray-tracing program, the luminance angular distribution of the light-guide plate engraved with the diffraction grating was calculated and compared to the luminance angular distribution for each actual prototype.
{"title":"Feasibility Study of the Light-outcoupling Characteristics of a Diffraction-grating-imprinted Light-guide Plate for an LCD Backlight Unit","authors":"Hwan-young Choi","doi":"10.3807/KJOP.2020.31.4.176","DOIUrl":"https://doi.org/10.3807/KJOP.2020.31.4.176","url":null,"abstract":"The possibility of replacing the condensing-prism film used in conventional backlight units with a light-guide plate engraved with a submicrometer-periodic diffraction grating was investigated. The optimal period for the diffraction grating was determined through simulation and experiment, and the transmission-mode efficiency of the diffraction grating was calculated in terms of the polar angle and azimuthal angle of the incident light. In addition, the effects of the two methods of optimizing the polar angle and the directional angle were compared by simulation, by suggesting the shape and configuration of the light-guide plate, so that more light could be extracted by diffraction. By using a ray-tracing program, the luminance angular distribution of the light-guide plate engraved with the diffraction grating was calculated and compared to the luminance angular distribution for each actual prototype.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"31 1","pages":"176-182"},"PeriodicalIF":0.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70161037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-08-01DOI: 10.3807/KJOP.2019.30.4.142
D. Yu, Young Jae Baek, Hyeon Joong Yong, O. Beomhoan
3D 영상을 구현하는 기술방식은 스테레오-스코픽 디스플 레이 방식과 3D 디스플레이 방식으로 나눌 수 있다. 3D 디 스플레이 방식 중에서도 체적형 방식 디스플레이(volumetric display)는 영상 평면이 아닌 실제 공간에 영상이 놓여있게 되는 부양영상을 나타내는데, 공중에 떠있는 실상이기 때문 에 직접적으로 관찰하고 서로 상호작용이 가능하며, 매우 큰 각도로 그 이미지를 볼 수 있다는 장점이 있다. 이러한 장점 을 응용해 3D 부양영상은 다양하게 응용될 수 있다. 체적형 방식 디스플레이를 나타내는 기술 중 재귀반사(retroreflector, rr)를 이용하는 기술은 큐브-모서리 재귀반사(corner cube retroreflector, CCRR) 판이나 병풍형-t(transverse directional)-rr판을 이용하여 부양영상을 형성하게 하는 것이다. Analysis of Quality Improvement of a Floating Image Using a Hybrid Retroreflective Mirror Array Sheet
实现3D视频的技术方式可分为立体声-斯科普里显示方式和3D显示方式。在3D显示方式中，体积式显示（volumetric display）显示的是悬浮在实际空间而不是影像平面上的影像，因为是悬浮在空中的真实影像，所以可以直接观察和相互交互，可以以很大的角度观看图像。应用这些优点，3D悬浮影像可以有多种应用。在表示体积型显示的技术中，利用递归反射（retreflector，rr）的技术是利用立方体-棱角递归反射（corner cube retreflector，CCRR）板或屏风型-t（横向定向）-rr板形成悬浮影像。Analysis of Quality Improvement of a Floating Image Using a Hybrid Retroreflective Mirror Array Sheet
{"title":"Analysis of Quality Improvement of a Floating Image Using a Hybrid Retroreflective Mirror Array Sheet","authors":"D. Yu, Young Jae Baek, Hyeon Joong Yong, O. Beomhoan","doi":"10.3807/KJOP.2019.30.4.142","DOIUrl":"https://doi.org/10.3807/KJOP.2019.30.4.142","url":null,"abstract":"3D 영상을 구현하는 기술방식은 스테레오-스코픽 디스플 레이 방식과 3D 디스플레이 방식으로 나눌 수 있다. 3D 디 스플레이 방식 중에서도 체적형 방식 디스플레이(volumetric display)는 영상 평면이 아닌 실제 공간에 영상이 놓여있게 되는 부양영상을 나타내는데, 공중에 떠있는 실상이기 때문 에 직접적으로 관찰하고 서로 상호작용이 가능하며, 매우 큰 각도로 그 이미지를 볼 수 있다는 장점이 있다. 이러한 장점 을 응용해 3D 부양영상은 다양하게 응용될 수 있다. 체적형 방식 디스플레이를 나타내는 기술 중 재귀반사(retroreflector, rr)를 이용하는 기술은 큐브-모서리 재귀반사(corner cube retroreflector, CCRR) 판이나 병풍형-t(transverse directional)-rr판을 이용하여 부양영상을 형성하게 하는 것이다. Analysis of Quality Improvement of a Floating Image Using a Hybrid Retroreflective Mirror Array Sheet","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"30 1","pages":"142-145"},"PeriodicalIF":0.1,"publicationDate":"2019-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42953235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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