Korean Journal of Optics and Photonics最新文献

{"title":"Femtosecond-Laser Micromachining of a Thermal Blocking Trench for an Enhanced PLC Variable Optical Attenuator","authors":"Dong-yoon Yoo, Hun-Kook Choi, I. Sohn, Young-Sic Kim, Su-Yong Kim, Wan-Chun Kim, Jin-Bong Kim","doi":"10.3807/KJOP.2016.27.4.127","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.4.127","url":null,"abstract":"In this paper, a trench structure was fabricated by femtosecond-laser machining to eliminate thermal crosstalk in a multichannel variable optical attenuator (VOA), to prevent decreasing attenuation efficiency of the VOA. Trenches of a variety of widths and depths were fabricated on the VOA chips by femtosecond-laser processing. After the machining, attenuation according to current change was observed in each VOA chip module with trenches. As a result, we could observe high responsivity of attenuation and low power consumption, and that the heat of each channel barely influenced other channels.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"127-132"},"PeriodicalIF":0.1,"publicationDate":"2016-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159415","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}

{"title":"Novel Optimization Method of Phase-Only Computer-Generated Hologram Using the Phase-Shift Characteristic","authors":"Taehyeon Kim, Bong-Sik Kim, W. Park","doi":"10.3807/KJOP.2016.27.3.101","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.3.101","url":null,"abstract":"In this study we propose the novel optimization method of the phase-only computer-generated hologram (CGH), to improve calculation speed compared to the conventional method. While the conventional method is calculated using numerical analysis, the novel method is calculated using the phase-shift characteristic of Fourier transformation. In addition, the selectivity of noise filtering lets it decrease the calculation time. The validity of the reconstructed image using the novel method is verified by comparing simulation results to ideal and conventional data, and the improvement of texture and sharpness of the reconstructed image is confirmed by simulation.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"101-105"},"PeriodicalIF":0.1,"publicationDate":"2016-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159812","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}

{"title":"Quasi-continuous-wave Yb-doped Fiber Lasers with 1.5 kW Peak Power","authors":"M. Jeon, Y. Jung, Ji Won Kim, Hoon Jeong","doi":"10.3807/KJOP.2016.27.3.095","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.3.095","url":null,"abstract":"High-power quasi-continuous-wave (qcw) operation in Yb-doped double-clad fiber lasers with near-diffraction-limited quality of the output beam is reported. Based on numerical simulation, we built a simple, all-fiberized Yb fiber laser, and a fiber-based master-oscillator power amplifier (MOPA). Both laser systems have successfully produced qcw output with average power greater than 150 W at 1080 nm and 10 ms pulse duration at 10 Hz repetition rate, corresponding to a peak power greater than 1.5 kW for 205 W of pump power at 976 nm. Laser performance, including beam quality and slope efficiency, was characterized in both configurations. Prospects for power scaling and applications are discussed.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"37 2 1","pages":"95-100"},"PeriodicalIF":0.1,"publicationDate":"2016-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159695","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}

{"title":"Fringe Sensitivity of Projection Moire Topography Due to Position of Light Source and Object Distance According to Grating Periods","authors":"Hyun Seock Oh, Yun Jae Ju, J. Jo","doi":"10.3807/KJOP.2016.27.2.067","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.2.067","url":null,"abstract":"In projection moire topography, the investigation of fringe sensitivity, which means the change rate of fringe order according to object height, is important and necessary to reduce the measurement error of the shape of an object. Using the fringe sensitivity, the determination of the absolute orders of moire fringes can be performed very easily and rapidly. The important parameters in the determination of absolute orders of fringes are the positions of light source and object, and the grating period in projection moire topography. Among these parameters, the fringe sensitivity due to the transverse motion of the light source and the longitudinal motion of the object according to grating periods are analyzed and compared. As a result, whereas the fringe sensitivity in the transverse-motion method increases linearly and gradually as the distance between light source and imaging sensor increases, the fringe sensitivity due to the longitudinal-motion method decreases dramatically as the distance between imaging lens and object increases. In these methods, the fringe sensitivity and its change increase as the grating period increases. Keywords: Projection Moire Topography, Moire fringe, fringe sensitivityOCIS codes: (120.4120) Moire’ techniques, (120.4640) Optical instruments, (100.3175) Interferometric imaging","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"67-72"},"PeriodicalIF":0.1,"publicationDate":"2016-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70158962","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}

{"title":"Design and Fabrication of a Light-Guiding Plate for a Photobioreactor Utilizing a Hybrid LED Plus Sunlight Source","authors":"Hyon-Chol Lim, Seung-Jin Yang, Jun-Hyeok Baek, Jae-Young Kim, Kyungmin Jang, Jongtye Kim, Sang-Hwa Jeong, Jong-Rak Park","doi":"10.3807/KJOP.2016.27.2.073","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.2.073","url":null,"abstract":"In this paper, we report the results of a study on the design and fabrication of a light-guiding plate (LGP) using a hybrid light-emitting diode (LED) and sunlight source that can be applied to a photobioreactor. LGP patterns for the LED source were designed and engraved on an LGP, together with previously reported patterns for a sunlight source. A control system for the hybrid LGP was designed to maintain the output photon flux density (PFD) from the LGP at a constant value. When the target value of the output PFD was set to 70 μE/(m 2 ·s), the error range of the output PFD was found to be within ±2%.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"73-80"},"PeriodicalIF":0.1,"publicationDate":"2016-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159043","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}

{"title":"A Study of Three-Dimensional Measurement By Transmission Deflectometry and Hilbert Transform","authors":"Silin Na, Younghun Yu","doi":"10.3807/KJOP.2016.27.2.061","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.2.061","url":null,"abstract":"We used transmission deflectometry to measure the three-dimensional shapes of optical components, and we used the Hilbert transform to retrieve the phases from measured deformed fringe images. Deflectometry is useful for measuring large-scale samples, and specular samples. We have retrieved the phases from deformed fringe images and Hilbert-transformed images, and have used the least-squares method to find the height information. We have verified that phase retrieval using Hilbert transform is useful by computer simulation and experiment.Keywords: Deflrctometry, Phase measuring deflectometry, Hilbert transformOCIS codes: (120.0120) Instrumentation, measurement, and metrology; (120.2650) Fringe analysis; (120.3940) Metrology","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"61-66"},"PeriodicalIF":0.1,"publicationDate":"2016-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159352","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}

{"title":"Infrared Characteristics of Some Flash Light Sources","authors":"Sangchul Lim, Seung-man Park","doi":"10.3807/KJOP.2016.27.1.018","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.1.018","url":null,"abstract":"To effectively utilize a flash and predict its effects on an infrared device, it is essential to know the infrared characteristics of the flash source. In this paper, a study of the IR characteristics of flash light sources is carried out. The IR characteristics of three flash sources, of which two are combustive and the other is explosive, are measured with an IR characteristic measurement system over the middle- and long-wavelength infrared ranges. From the measurements, the radiances over the two IR ranges and the radiative temperatures of the flashes are extracted. The IR radiance of flash A is found to be the strongest among the three, followed by those of sources C and B. It is also shown that the IR radiance of flash A is about 10 times stronger than that of flash B, even though these two sources are the same type of flash with the same powder. This means that the IR radiance intensity of a combustive flash source depends only on the amount of powder, not on the characteristics of the powder. From the measured radiance over MWIR and LWIR ranges for each flashes, the radiative temperatures of the flashes are extracted by fitting the measured data to blackbody radiance. The best-fit radiative temperatures (equivalent to black-body temperatures) of the three flash sources A, B, and C are 3300, 1120, and 1640 K respectively. From the radiance measurements and radiative temperatures of the three flash sources, it is shown that a combustive source radiates more IR energy than an explosive one; this mean, in turn, that the effects of a combustive flash on an IR device are more profound than those of an explosive flash source. The measured IR radiances and radiative temperatures of the flash sources in this study can be used to estimate the effects of flashes on various IR devices, and play a critical role for the modeling and simulation of the effects of a flash source on various IR devices.Keywords: Flash lights, Spectral radiance, Radiative temperature, Pyroelectric IR detectorOCIS codes: (040.3060) Infrared; (200.4560) Optical data processing, (350.5610) Radiation, (040.6808) Thermal (uncooled) IR detectors, arrays and imaging","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"18-24"},"PeriodicalIF":0.1,"publicationDate":"2016-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159015","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}

{"title":"Designing the Optical Structure of a Multiscale Gigapixel Camera","authors":"H. J. Moon, C. Rim","doi":"10.3807/KJOP.2016.27.1.025","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.1.025","url":null,"abstract":"We derive 28 optical structural equations based on our two previous theoretical and experimental papers about a gigapixel camera, which were published in 2013 and 2015 respectively. Utilizing these 28 equations, we are able to obtain an integrated understanding of optical structure for a multiscale gigapixel camera system, in addition to obtaining numerical values for structural parameters very directly and easily.Keywords: Giga pixel camera, Multiscale, Monocentric objective, Microcamera lensOCIS codes: (080.0080) Geometric optics; (080.2468) First-order optics; (080.2740) Geometric optical design; (080.3620) Lens system design","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"25-31"},"PeriodicalIF":0.1,"publicationDate":"2016-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159081","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}

{"title":"Current Status and Prospects of High-Power Fiber Laser Technology (Invited Paper)","authors":"Youngchul Kwon, Kyoungyoon Park, Dongyeul Lee, HanByul Chang, Seungjong Lee, L. A. Vazquez-Zuniga, Y. S. Lee, D. H. Kim, Hyuntae Kim, Y. Jeong","doi":"10.3807/KJOP.2016.27.1.001","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.1.001","url":null,"abstract":"Over the past two decades, fiber-based lasers have made remarkable progress, now having reached power levels exceeding kilowatts and drawing a huge amount of attention from academy and industry as a replacement technology for bulk lasers. In this paper we review the significant factors that have led to the progress of fiber lasers, such as gain-fiber regimes based on ytterbium-doped silica, optical pumping schemes through the combination of laser diodes and double-clad fiber geometries, and tandem schemes for minimizing quantum defects. Furthermore, we discuss various power-limitation issues that are expected to incur with respect to the ultimate power scaling of fiber lasers, such as efficiency degradation, thermal hazard, and system-instability growth in fiber lasers, and various relevant methods to alleviate the aforementioned issues. This discussion includes fiber nonlinear effects, fiber damage, and modal-instability issues, which become more significant as the power level is scaled up. In addition, we also review beam-combining techniques, which are currently receiving a lot of attention as an alternative solution to the power-scaling limitation of high-power fiber lasers. In particular, we focus more on the discussion of the schematics of a spectral beam-combining system and their individual requirements. Finally, we discuss prospects for the future development of fiber laser technologies, for them to leap forward from where they are now, and to continue to advance in terms of their power scalability.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"1-17"},"PeriodicalIF":0.1,"publicationDate":"2016-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70158930","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}

{"title":"Three-Dimensional Shape Measurement of a Specular Object by LED Array Reflection","authors":"Jeehong Kim","doi":"10.3807/KJOP.2016.27.1.041","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.1.041","url":null,"abstract":"본 논문은 경면체의 3차원 형상을 측정하기 위한 광학시스템에 관한 것으로, 특히 LED 배열로 이루어진 점광원과 하프미러, 이미지센서로 구성된 비전시스템을 구성하여 광로분석을 수행하고 효과적인 근사화 방법을 제시한다. 실험을 통하여 취득된 영상 내의 점광원의 상대적 위치변화로부터 경면체의 3차원형상의 효과적 추정이 가능함을 보인다. 【An optical method to measure the three-dimensional (3D) shape of a surface with specular reflection is proposed. The proposed method is based on the analysis of the geometric path of the light from a point source, and the relative displacements of points in the reflection image. The 3D shape of a concave mirror is shown to be determined approximately via experiments, where the vision system consists of LED array illumination, a half-mirror, and an imaging sensor.】","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"41-46"},"PeriodicalIF":0.1,"publicationDate":"2016-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159261","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}