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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Optical Society of Korea
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Journal DOI :
Optical Society of Korea
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Volume & Issues
Volume 19, Issue 6 - Dec 2015
Volume 19, Issue 5 - Oct 2015
Volume 19, Issue 4 - Aug 2015
Volume 19, Issue 3 - Jun 2015
Volume 19, Issue 2 - Apr 2015
Volume 19, Issue 1 - Feb 2015
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Performance of All-Optical Multihop RoFSO Communication System over Gamma-Gamma Atmospheric Turbulence Channels
Zong, Kang ; Zhu, Jiang ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 437~443
DOI : 10.3807/JOSK.2015.19.5.437
In this paper, we analyze the performance of the all-optical multihop radio over a free space optical (RoFSO) communication system with amplify-and-forward (AF) relays under varying weather conditions. The proposed channel model considers the propagation loss, attenuation and atmospheric fading modeled by the Gamma-Gamma (GG) distribution. Both the amplified spontaneous emission (ASE) noise in the all-optical relays and the background noise projected onto receiver apertures have been considered in the analysis. The lower bound analytical expressions for the end-to-end bit error rate (BER) and outage probability are derived for the multihop system employing the all-optical relays with the full channel state information (CSI). Meanwhile, the exact results for BER and outage probability are obtained via Monte Carlo simulation. Results indicate the performance of the proposed system will be improved by the multihop transmission technology. For a fixed number of relays, the BER and outage probability will be increased with the deterioration of the weather conditions.
Simulation for Propagation Behavior of a Gaussian Beam in Water Medium by Monte Carlo Method
Kim, Jae-Ihn ; Jeong, Woong-Ji ; Cho, Joon-Yong ; Jo, Min-Sik ; Kim, Hyung-Rok ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 444~448
DOI : 10.3807/JOSK.2015.19.5.444
We describe the radiative transfer of a Gaussian beam in a water medium using the Monte Carlo method offering basic propagation behaviors. The simulation shows how the energy of the initial Gaussian beam is redistributed as it propagates in coastal water, and also depicts the dependence of the propagation behavior on inherent optical properties of the ocean water such as the single scattering albedo as well as on laser beam parameters, e.g. the M squared. Our results may widen the applicability of LIDARs by providing a couple of design considerations for a bathymetric LIDAR.
Hybrid Square-Lattice Photonic Crystal Fiber with Broadband Single-Mode Operation, High Birefringence, and Normal Dispersion
Kim, Soeun ; Lee, Yong Soo ; Lee, Chung Ghiu ; Jung, Yongmin ; Oh, Kyunghwan ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 449~455
DOI : 10.3807/JOSK.2015.19.5.449
In this study we propose a new photonic crystal fiber (PCF) design that simultaneously offers broadband single-mode operation, high birefringence, and large normal dispersion in the optical-communication wavelength regime. The waveguide is based on a hybrid square-lattice PCF (HS-PCF) that has circular air holes of two different diameters alternating in the cladding, plus a pure silica defect at the center. The optical properties of the guided modes are analyzed numerically by the finite-element method (FEM) with a perfectly matched layer as the boundary condition. The optimized HS-PCF has a dispersion coefficient of
and a high birefringence of
. In addition, over the S+C+L+U wavelength bands the proposed HS-PCF with ultraflat birefringence with a slope on the order of
Optimized Optomechanical Anti-Aliasing Filter for Digital Camera Photography
Lee, Sang Won ; Chang, Ryungkee ; Moon, Sucbei ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 456~466
DOI : 10.3807/JOSK.2015.19.5.456
We investigated an anti-aliasing (AA) filter for digital camera photography by which the excessively high-frequency components of the image signal are suppressed to avoid the aliasing effect. Our optomechanical AA filter was implemented by applying rapid relative motions to the imaging sensor. By the engineered motion blur of the mechanical dithers, the effective point-spread function (PSF) of the imaging system could be tailored to reject the unwanted high-frequency components of the image. For optimal operations, we developed a spiral filter motion protocol that could produce a Gaussian-like PSF. We experimentally demonstrated that our AA filter provides an improved filtering characteristic with a better compromise of the rejection performance and the signal loss. We also found that the pass band characteristic can be enhanced further by a color-differential acquisition mode. Our filter scheme provides a useful method of digital photography for low-error image measurements as well as for ordinary photographic applications where annoying
patterns must be suppressed efficiently.
Reflection-type Finger Vein Recognition for Mobile Applications
Zhang, Congcong ; Liu, Zhi ; Liu, Yi ; Su, Fangqi ; Chang, Jun ; Zhou, Yiran ; Zhao, Qijun ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 467~476
DOI : 10.3807/JOSK.2015.19.5.467
Finger vein recognition, which is a promising biometric method for identity authentication, has attracted significant attention. Considerable research focuses on transmission-type finger vein recognition, but this type of authentication is difficult to implement in mobile consumer devices. Therefore, reflection-type finger vein recognition should be developed. In the reflection-type vein recognition field, the majority of researchers concentrate on palm and palm dorsa patterns, and only a few pay attention to reflection-type finger vein recognition. Thus, this paper presents reflection-type finger vein recognition for biometric application that can be integrated into mobile consumer devices. A database is built to test the proposed algorithm. A novel method of region-of-interest localization for a finger vein image is introduced, and a scheme for effectively extracting finger vein features is proposed. Experiments demonstrate the feasibility of reflection-type finger vein recognition.
Calibration Method for the Panel-type Multi-view Display
Kim, Jonghyun ; Lee, Chang-Kun ; Hong, Jong-Young ; Jang, Changwon ; Jeong, Youngmo ; Yeom, Jiwoon ; Lee, Byoungho ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 477~486
DOI : 10.3807/JOSK.2015.19.5.477
We propose a novel calibration method which can be applied to all kinds of panel-type multi-view displays. We analyze how the angular, the axial, and the lateral misalignment affects the 3D image quality in a panel-type multi-view display. We demonstrate the ray optics simulation with a 3-view slanted parallax barrier system using pentile display for the quantitative calculation. Based on the analysis, we propose a new alignment pattern for all kinds of panel-type multi-view displays. The proposed pattern is sensitive to all of the angular, the axial, and the lateral misalignments. The high spatial frequency images and on and off alignment in the proposed pattern help observers to calibrate the system easily. We theoretically show the generality of the proposed alignment pattern and verify the pattern with image simulations and experiments.
Optimization of Wavefront Coding Phase Mask Applied to 5X-40X Micro-Objectives Simultaneously
Liu, Jiang ; Miao, Erlong ; Sui, Yongxin ; Yang, Jianghuai ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 487~493
DOI : 10.3807/JOSK.2015.19.5.487
A wavefront coding (WFC) technique provides an extension of the depth of field for a microscopy imaging system with slight loss of image spatial resolution. Through the analysis of the relationship between the incidence angle of light at the phase mask and the system pupil function, a mixing symmetrical cubic phase mask (CPM) applied to 5X-40X micro-objectives is optimized simultaneously based on point-spread function (PSF) invariance and nonzero mean values of the modulation transfer function (MTF) near the spatial cut-off frequency. Optimization results of the CPM show that the depth of field of these micro-objectives is extended 3-10 times respectively while keeping their resolution. Further imaging simulations also prove its ability in enhancing the defocus imaging.
Vibration Measurement Using a Fringe Pattern in Reflective Monochromatic Interferometry
Kim, Minsu ; Yoon, Do-Young ; Pahk, Heuijae ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 494~502
DOI : 10.3807/JOSK.2015.19.5.494
This paper introduces methods to measure vibration using a fringe pattern. These methods use variations of a fringe pattern in reflective monochromatic interferometry, without additional components. With the proposed methods we measured the vibrations of four waveform with amplitude 100 nm. When the vibrational amplitude is greater than a quarter wavelength of the light employed, however, the measured results are distorted due to ambiguity. Thus we propose advanced methods to solve this problem, and also measure the vibrations of two waveformswith an amplitude of
. To verify the performance of the proposed methods, we compare the results to those from an accelerometer. Multifrequency vibrations of 1, 5, 10, and 20 Hz are measured by both techniques, and the results compared in the frequency domain.
Measuring the Thickness of Flakes of Hexagonal Boron Nitride Using the Change in Zero-Contrast Wavelength of Optical Contrast
Kim, Dong Hyun ; Kim, Sung-Jo ; Yu, Jeong-Seon ; Kim, Jong-Hyun ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 503~507
DOI : 10.3807/JOSK.2015.19.5.503
Using the reflectivity mode of an optical microscope, we analyzed the optical contrast to identify the layer number of flakes of hexagonal boron nitride on a
/Si substrate. Overall optical contrast in the visible range varies with the thickness of flakes. However, the wavelength of zero contrast exhibits a linear redshift of 0.53 nm per layer, independent of the
thickness, and increases proportionally with
thickness. Experiments show good agreement with calculations and the results of AFM measurements. These results show that this zero-contrast approach is more accurate and easier than the reflectivity-contrast approach using the overall optical contrast.
Highly Flexible Touch Screen Panel Fabricated with Silver Nanowire Crossing Electrodes and Transparent Bridges
Jeon, Youngeun ; Jin, Han Byul ; Jung, Sungchul ; Go, Heungseok ; Lee, Innam ; Lee, Choonhyop ; Joo, Young Kuil ; Park, Kibog ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 508~513
DOI : 10.3807/JOSK.2015.19.5.508
A capacitive-type touch screen panel (TSP) composed of silver nanowire (AgNW) crossing electrodes and transparent bridge structures was fabricated on a polycarbonate film. The transparent bridge structure was formed with a stack of Al-doped ZnO (AZO) electrodes and SU-8 insulator. The stable and robust continuity of the bridge electrode over the bridge insulator was achieved by making the side-wall slope of the bridge insulator low and depositing the conformal AZO film with atomic layer deposition. With an extended exposure time of photolithography, the lower part of the SU-8 layer around the region uncovered by the photomask can be exposed enough to the UV light scattered from the substrate. This leads to the low side-wall slope of the bridge insulator. The fabricated TSP sample showed a large capacitance change of 22.71% between with and without touching. Our work supplies the technological clue for ensuring long-term reliability to the highly flexible and transparent TSP made by using conventional fabrication processes.
High-Performance Time-Code Diversity Scheme for Shore-to-Sea Maritime Visible-Light Communication
Kim, Hyeongji ; Sewaiwar, Atul ; Chung, Yeon-Ho ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 514~520
DOI : 10.3807/JOSK.2015.19.5.514
This paper presents a novel shore-to-sea maritime data transmission system based on time-code diversity, using visible light in maritime environments to overcome the limitations of conventional maritime wireless communications. The proposed system is primarily comprised of existing LED-based lighthouses and maritime transceivers (marine beacons, buoys, etc.), and thus is considered cost-effective in terms of implementation. We first analyze maritime visible-light communications on the basis of the unique properties of a maritime environment, i.e. sea states (wave height, wind speed, etc.), plus atmospheric turbulence, using the Pierson-Moskowitz (PM) and JONSWAP (JS) spectrum models. It is found that the JS model outperforms the PM model, and that the coverage distance depends on the LED power and sea states. To combat maritime fading conditions that significantly degrade performance and coverage distance, we propose a time-code diversity (TCD) scheme in which the delayed versions of the original data are retransmitted using orthogonal Walsh codes. This TCD scheme is found to be superior, in that it offers three orders of magnitude in terms of BER performance, compared to a conventional (non-TCD) transmission scheme. The proposed scheme is robust and efficient in overcoming the effect of impairments present in maritime environments with a BER of approximately
and a data rate of 100 Kbps at a distance of 1 km.
Integrated Modeling for the Design of Deformable Mirrors Using a Parametric Module Method
Zhu, Junqing ; Sha, Wei ; Chen, Changzheng ; Zhang, Xingxiang ; Ren, Jianyue ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 521~530
DOI : 10.3807/JOSK.2015.19.5.521
Active optics is a key technology for future large-aperture space telescopes. In the design of deformable mirrors for space applications, the design parameter trade-off between the number of regularly configured actuators and the correction capability is essential but rarely analyzed, due to the lack of design legacy. This paper presents a parametric module method for integrated modeling of deformable mirrors with regularly configured actuators. A full design parameter space is explored to evaluate the correction capability and the mass of deformable mirrors, using an autoconstructed finite-element parametric modeling method that utilizes manual finite-element meshing for complex structures. These results are used to provide design guidelines for deformable mirrors. The integrated modeling method presented here can be used for future applied optics projects.
Graphical Selection of Optical Materials Using an Expanded Athermal Glass Map and Considering the Housing Material for an Athermal and Achromatic Design
Lim, Tae-Yeon ; Kim, Yeong-Sik ; Park, Sung-Chan ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 531~536
DOI : 10.3807/JOSK.2015.19.5.531
This paper presents a new graphical method for selecting a pair of optical glass and housing materials to simultaneously achromatize and athermalize a multilens system composed of many elements. To take into account the lens spacing and housing, we quantify the lens power, chromatic power, and thermal power by weighting the ratio of the paraxial ray height at each lens to them. In addition, we introduce the equivalent single lens and the expanded athermal glass map including a housing material. Even though a lens system is composed of many elements, we can simply identify a pair of glass and housing materials that satisfies the athermal and achromatic conditions. Applying this method to design a black box camera lens equipped with a 1/4-inch image sensor having a pixel width of
, the chromatic and thermal defocusings are reduced to less than the depth of focus, over the specified ranges in temperature and frequency.
Robust Motion Compensated Frame Interpolation Using Weight-Overlapped Block Motion Compensation with Variable Block Sizes to Reduce LCD Motion Blurs
Lee, Jichan ; Choi, Jin Hyuk ; Lee, Daeho ;
Journal of the Optical Society of Korea, volume 19, issue 5, 2015, Pages 537~543
DOI : 10.3807/JOSK.2015.19.5.537
Liquid crystal displays (LCDs) have slow responses, so motion blurs are often perceived in fast moving scenes. To reduce this motion blur, we propose a novel method of robust motion compensated frame interpolation (MCFI) based on bidirectional motion estimation (BME) and weight-overlapped block motion compensation (WOBMC) with variable block sizes. In most MCFI methods, a static block size is used, so some block artefacts and motion blurs are observed. However, the proposed method adjusts motion block sizes and search ranges by comparing matching scores, so the precise motion vectors can be estimated in accordance with motions. In the MCFI, overlapping ranges for WOBMC are also determined by adjusted block sizes, so the accurate MCFI can be performed. In the experimental results, the proposed method strongly reduced motion blurs arisen from large motions, and yielded interpolated images with high visual performance and peak signal-to-noise ratio (PSNR).