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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 16, Issue 4 - Dec 2012
Volume 16, Issue 3 - Sep 2012
Volume 16, Issue 2 - Jun 2012
Volume 16, Issue 1 - Mar 2012
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Implementation of Differential Absorption LIDAR (DIAL) for Molecular Iodine Measurements Using Injection-Seeded Laser
Choi, Sungchul ; Baik, Sunghoon ; Park, Seungkyu ; Park, Nakgyu ; Kim, Dukhyeon ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 325~330
DOI : 10.3807/JOSK.2012.16.4.325
Differential absorption LIDAR (DIAL) is frequently used for atmospheric gas monitoring to detect impurities such as nitrogen dioxide, sulfur dioxide, iodine, and ozone. However, large differences in the on- and off-line laser wavelengths can cause serious errors owing to differential aerosol scattering. To resolve this problem, we have developed a new DIAL system for iodine vapor measurements in particular. The suggested DIAL system uses only one laser under seeded and unseeded conditions. To check the detection-sensitivity and error effects, we compared the results from a system using two seeded lasers with those from a system using a seeded and an unseeded laser. We demonstrate that the iodine concentration sensitivity of our system is improved in comparison to the conventional two seeded or two unseeded laser combinations.
Compact Infrared/Visible Laser Transmitter Featuring an Extended Detectable Trajectory
Kim, Haeng-In ; Lee, Hong-Shik ; Lee, Sang-Shin ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 331~335
DOI : 10.3807/JOSK.2012.16.4.331
A miniaturized laser beam transmitter, in which a visible laser module at
=650 nm is precisely stacked upon an infrared (IR) module at
=905 nm, has been proposed and constructed to provide an IR collimated beam in conjunction with a collinear monitoring visible beam. In particular, the IR beam is selectively dispersed through a perforated sheet diffuser, so as to create a rapidly diverging close-range beam in addition to a highly defined long-range beam simultaneously. The complementary close-range beam plays a role in mitigating the blind region in the vicinity of the transmitter, which is inevitably missed by the main long-range beam, thereby uniformly extending the transmitter's effective trajectory that is sensed by a receiver. The proposed transmitter was designed through numerical simulations and then fabricated by incorporating a diffuser sheet, perforated with an aperture of 2 mm. For the manufactured transmitter, the IR long-range beam was observed to have divergences of ~2.3 and 1.6 mrad in the fast and slow axes, respectively, while the short-range beam yielded a divergence of ~24 mrad. The angular alignment between the long-range IR and visible beams was as accurate as ~0.5 mrad. According to an outdoor feasibility test involving a receiver, the combination of the IR long- and short-range beams was proven to achieve a nearly uniform trajectory over a distance ranging up to ~600 m, with an average detectable cross-section of
A Low-cost Optimization Design for Minimizing Chromatic Aberration by Doublet Prisms
Sun, Wen-Shing ; Tien, Chuen-Lin ; Sun, Ching-Cherng ; Lee, Ching-Chun ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 336~342
DOI : 10.3807/JOSK.2012.16.4.336
A low-cost optimal double-prism method is proposed by using the developed MATLAB program to correct chromatic aberration. We present an efficient approach to choose a couple of low-cost glasses to obtain a low aberration double prism. The doublet prisms were made of two lead-free glasses. The relative partial dispersion of the two lead-free glasses is identical and their Abbe numbers are different greatly. The proposed design aims to minimize chromatic aberration, such as in apochromats, for paraxial ray tracing. Finally, an optimization design for real ray tracing can be evaluated by the chromatic aberration curve with a minimal area.
Optical Design of an Off-axis Five-mirror-anastigmatic Telescope for Near Infrared Remote Sensing
Li, Xing Long ; Xu, Min ; Pei, Yun Tian ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 343~348
DOI : 10.3807/JOSK.2012.16.4.343
This paper described an off-axis five-mirror-anastigmatic telescope. It is composed of three aspheric surfaces and one spherical surface while the third mirror and fifth mirror have the same parameters at the same place. This configuration is useful for having wide field of view. The strip full field of view for the near infrared telescope is
. The entrance pupil is located in front of the first mirror. There is an intermediate image between the second mirror and the third mirror. The entrance pupil diameter is 100 mm and the effective focal length is 250 mm. The spectral range is
. The pixel pitch is
. The image quality is near the diffraction limit. Some methods were used to restrain the stray light such as a field stop near the intermediate image, the baffle, the narrow-band pass filter and a stop in front of the focal plane.
Fabrication and Characterization of a GaN Light-emitting Diode (LED) with a Centered Island Cathode
Park, Yun Soo ; Lee, Hwan Gi ; Yang, Chung-Mo ; Kim, Dong-Seok ; Bae, Jin-Hyuk ; Cho, Seongjae ; Lee, Jung-Hee ; Kang, In Man ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 349~353
DOI : 10.3807/JOSK.2012.16.4.349
Uniform spreading of injection current in light-emitting diodes (LEDs) is one of the crucial requirements for better device performances. It is reported that non-uniform current spreading leads to low output power, high current crowding, heating, and reliability degradation of the LED device. This paper reports on the effects of different surface and electrode geometries in the LEDs. To increase the output power of LEDs and reduce the series resistance, a rectangular-type LED (RT-LED) with a centered island cathode has been fabricated and investigated by comparison with a conventional LED (CV-LED). The performances of RT-LEDs were prominently enhanced via uniform current spreading and low current crowding. Performances in terms of increased output power and lower forward voltage of simulated RT-LEDs are much superior to those of CV-LEDs. Based on these results, we investigated the correlation between device geometries and optical characteristics through the fabricated CV and RT-LEDs. The measured output power and forward voltage of the RT-LEDs at 100 mA are 64.7% higher and 8% smaller compared with those of the CV-LEDs.
2-step Quadrature Phase-shifting Digital Holographic Optical Encryption using Orthogonal Polarization and Error Analysis
Gil, Sang Keun ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 354~364
DOI : 10.3807/JOSK.2012.16.4.354
In this paper, a new 2-step quadrature phase-shifting digital holographic optical encryption method using orthogonal polarization is proposed and tolerance errors for this method are analyzed. Unlike the conventional technique using a PZT mirror, the proposed optical setup comprises two input and output polarizers, and one
/4-plate retarder. This method makes it easier to get a phase shift of
/2 without using a mechanically driven PZT device for phase-shifting and it simplifies the 2-step phase-shifting Mach-Zehnder interferometer setup for optical encryption. The decryption performance and tolerance error analysis for the proposed method are presented. Computer experiments show that the proposed method is an alternate candidate for 2-step quadrature phase-shifting digital holographic optical encryption applications.
Integral-floating Display with 360 Degree Horizontal Viewing Angle
Erdenebat, Munkh-Uchral ; Baasantseren, Ganbat ; Kim, Nam ; Kwon, Ki-Chul ; Byeon, Jina ; Yoo, Kwan-Hee ; Park, Jae-Hyeung ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 365~371
DOI : 10.3807/JOSK.2012.16.4.365
A three-dimensional integral-floating display with 360 degree horizontal viewing angle is proposed. A lens array integrates two-dimensional elemental images projected by a digital micro-mirror device, reconstructing three-dimensional images. The three-dimensional images are then relayed to a mirror via double floating lenses. The mirror rotates in synchronization with the digital micro-mirror device to direct the relayed three-dimensional images to corresponding horizontal directions. By combining integral imaging and the rotating mirror scheme, the proposed method displays full-parallax three-dimensional images with 360 degree horizontal viewing angle.
Assessment of Gradient-based Digital Speckle Correlation Measurement Errors
Jian, Zhao ; Dong, Zhao ; Zhe, Zhang ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 372~380
DOI : 10.3807/JOSK.2012.16.4.372
The optical method Digital Speckle Correlation Measurement (DSCM) has been extensively applied due its capability to measure the entire displacement field over a body surface. A formula of displacement measurement errors by the gradient-based DSCM method was derived. The errors were found to explicitly relate to the image grayscale errors consisting of sub-pixel interpolation algorithm errors, image noise, and subset deformation mismatch at each point of the subset. A power-law dependence of the standard deviation of displacement measurement errors on the subset size was established when the subset deformation was rigid body translation and random image noise was dominant and it was confirmed by both the numerical and experimental results. In a gradient-based algorithm the basic assumption is rigid body translation of the interrogated subsets, however, this is in contradiction to the real circumstances where strains exist. Numerical and experimental results also indicated that, subset shape function mismatch was dominant when the order of the assumed subset shape function was lower than that of the actual subset deformation field and the power-law dependence clearly broke down. The power-law relationship further leads to a simple criterion for choosing a suitable subset size, image quality, sub-pixel algorithm, and subset shape function for DSCM.
Simplified Integral Imaging Pickup Method for Real Objects Using a Depth Camera
Li, Gang ; Kwon, Ki-Chul ; Shin, Gwan-Ho ; Jeong, Ji-Seong ; Yoo, Kwan-Hee ; Kim, Nam ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 381~385
DOI : 10.3807/JOSK.2012.16.4.381
In this paper, we present a novel integral imaging pickup method. We extract each pixel's actual depth data from a real object's surface using a depth camera, then generate elemental images based on the depth map. Since the proposed method generates elemental images without a lens array, it has simplified the pickup process and overcome some disadvantages caused by a conventional optical pickup process using a lens array. As a result, we can display a three-dimensional (3D) image in integral imaging. To show the usefulness of the proposed method, an experiment is presented. Though the pickup process has been simplified in the proposed method, the experimental results reveal that it can also display a full motion parallax image the same as the image reconstructed by the conventional method. In addition, if we improve calculation speed, it will be useful in a real-time integral imaging display system.
Alleviating Light Leakage in LCDs via Diverse Modifications of Polarizer Film
Jeon, Il ; Yoon, MinSung ; Lee, Je-Hoon ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 386~395
DOI : 10.3807/JOSK.2012.16.4.386
In this paper, we identify an intractable problem known as light leakage, which is more critical in IPS mode compared to VA mode, and we propose diverse ways of tackling this issue. In general, the light leakage phenomenon arises from the stress generated by the bending of the LCD panel. This paper proposes three processing methods for reducing the mechanical stress causing LCD panel bending and light leakage. Changes in the lamination process of polarizer films and the application of a buffer layer can reduce the bending level by 32% and 21%, respectively. The combination of polarizer films according to variation of thickness also help to reduce the panel bending. In particular, it is important that a combination of these proposed modifications could provide the better solution to reduce the panel bending. From a geometric solution to a change in materials, the whole history of IPS light leakage solutions is presented succinctly. With this paper-or review, to be more precise-the mechanism underlying the light leakage phenomenon is understood, and this understanding is applied to derive answers to the problem caused by the phenomenon in question.
Theoretical Considerations on Combined Optical Distance Measurements Using a Femtosecond Pulse Laser
Joo, Ki-Nam ; Kim, Seung-Woo ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 396~400
DOI : 10.3807/JOSK.2012.16.4.396
We introduce a combined technique and the mathematical description for distance measurements using a femtosecond pulse laser in a long range and a fine resolution. For distance measurements, the maximum measurable range can be extended by combining measurement results from several different methods while requiring relationships between the different measurement uncertainties and unambiguity ranges. This paper briefly explains why the uncertainty of a rough measurement technique (RMT) should be, at least, smaller than the half unambiguity range of a fine measurement technique (FMT) in order to combine a FMT with a RMT. Further discussions about the total measurement range, resolution, and uncertainty for various optical measurement techniques are also discussed.
Amplitude Control of Phase Modulation for Dithered Closed-loop Fiber Optic Gyroscope
Chong, Kyoung-Ho ; Chong, Kil-To ; Kim, Young-Chul ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 401~408
DOI : 10.3807/JOSK.2012.16.4.401
The amplitude error of phase modulator used in closed-loop fiber optic gyroscope has occurred by the temperature dependency of the electro-optic coefficient, and also can be due to the square-wave dither signal which is generally applied for eliminating the deadzone. This error can cause bias drift and scale factor error. This paper analyzes the temperature dependency of the modulation amplitude and the relationship with the scale factor of the gyroscope, and deals with an amplitude control method. The error calculation logic considering the dither signal is implemented on the signal processing module. The result of experiments from a prototype gyroscope shows the effect of the modulation amplitude control and a considerable improvement on performances.
Dark-state Color Shift and Gray Scale Inversion in an In-plane Switching Liquid Crystal Display Device
Park, Sung Il ; Park, Kyoung-Ho ; Lee, Joun-Ho ; Yoon, Jeong Hwan ; Kim, Byeong Koo ; Yu, Byeong-Hun ; Kim, Ki-Han ; Yoon, Tae-Hoon ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 409~413
DOI : 10.3807/JOSK.2012.16.4.409
Off-axis color shift in the dark state and gray scale inversion in an in-plane switching (IPS) liquid crystal display (LCD) device were investigated. Analyses were performed using the Poincar
sphere representation. The results show that color shift in the dark state and gray scale inversion in an IPS LCD can be reduced by using a biaxial film. We confirmed the extent of these improvements by measuring the optical performance of a fabricated IPS LCD.
The Effect of Cerium Reduction on Light Emission in Cerium-containing 20Y
Maeng, Jee-Hun ; Choi, Sung-Churl ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 414~417
DOI : 10.3807/JOSK.2012.16.4.414
The effect of cerium concentration and the addition of
on the light emission of cerium-contained glass were investigated. The glass matrix composition was
concentration ranged from 0.05 to 0.5 mol%, and
was added at concentrations of 0.02 to 0.1 mol%. The
absorption bands were observed at approximately 330 nm and 240 nm, respectively. A broad emission band at 400 nm, due to the 4f-5d transition of the
ion, was observed under illumination by a UV light at 330 nm. The photoluminescence intensity of
had a maximum value at a
concentration of 0.1 mol%. Adding
absorption intensity and enhanced the light emission intensity of
by about 45%.
Repeatability and Reliability of a New Phoria Test Using Flashed and Auto-flashed Presentation
Moon, Byeong-Yeon ; Park, Sun-Young ; Cho, Hyun Gug ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 418~424
DOI : 10.3807/JOSK.2012.16.4.418
The purpose of this study was to assess repeatability and reliability of a new phoria test as compared to established phoria tests and to assess the possibility of mobile or online testing using the auto-flashed presentation. Near dissociated phoria was measured using the von Graefe method, the Howell card test, the modified Thorington test, and a new dichromatic card test (Red-Blue Phoria card test; RBP card test) on 109 subjects. The inter-examiner difference and test-retest difference were calculated. With the auto-flashed presentation of the RBP card test, near dissociated phoria was measured and the intraclass correlation coefficient and test-retest repeatability was assessed on 26 subjects. The variation in inter-examiner repeatability was the smallest for the modified Thorington test (+3.1/-2.6). The RBP card test was +3.0/-3.1, the Howell card test was +3.5/-2.7, and the von Graefe test was +6.2/-6.0. The variation in test-retest repeatability was the smallest for the RBP card test (+0.4/-1.4). The modified Thorington test was +1.3/-1.3, the Howell card test was +1.27/-1.45, and the von Graefe test was +1.59/-2.20. The ICC was 0.919 for the auto-flashed presentation of the RBP card test. The RBP card test is considered a highly repeatable method clinically and can be made a useful application for testing in mobile or online.
Three-dimensional Spatiotemporal Accessible Solitons in a PT-symmetric Potential
Zhong, Wei-Ping ; Belic, Milivoj R. ; Huang, Tingwen ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 425~431
DOI : 10.3807/JOSK.2012.16.4.425
Utilizing the three-dimensional Snyder-Mitchell model with a PT-symmetric potential, we study the influence of PT symmetry on beam propagation in strongly nonlocal nonlinear media. The complex Coulomb potential is used as the PT-symmetric potential. A localized spatiotemporal accessible soliton solution of the model is obtained. Specific values of the modulation depth for different soliton parameters are discussed. Our results reveal that in these media the localized solitons can exist in various shapes, such as single-layer and multi-layer disk-shaped structures, as well as vortex-ring and necklace patterns.
All Optical Logic Gates Based on Two Dimensional Plasmonic Waveguides with Nanodisk Resonators
Dolatabady, Alireza ; Granpayeh, Nosrat ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 432~442
DOI : 10.3807/JOSK.2012.16.4.432
In this paper, we propose, analyze and simulate the performances of some new plasmonic logic gates in two dimensional plasmonic waveguides with nanodisk resonators, using the numerical method of finite difference time domain (FDTD). These gates, including XOR, XNOR, NAND, and NOT, can provide the highly integrated optical logic circuits. Also, by cascading and combining these basic logic gates, any logic operation can be realized. These devices can be utilized significantly in optical processing and telecommunication devices.
Polarimetric Measurement of Jones Matrix of a Twisted Nematic Liquid Crystal Spatial Light Modulator
Khos-Ochir, Tsogvoo ; Munkhbaatar, Purevdorj ; Yang, Byung Kwan ; Kim, Hyun Woo ; Kim, Jin Seung ; Kim, Myung-Whun ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 443~448
DOI : 10.3807/JOSK.2012.16.4.443
A polarimetric experimental method was developed to determine the Jones matrix elements of transparent optical materials without sign ambiguity. A set of polarization dependent transmittance data of the samples was measured with polarizer - sample - analyzer system and another set of data was measured with polarizer - sample - quarter-wave plate - analyzer. Two data sets were compared and mathematically analyzed to obtain the correct signs of the elements of the matrix. The Jones matrix elements of a quarter-wave plate were determined to check the validity of the method. The experimentally obtained matrix elements of the quarter-wave plate were consistent with the theoretical expectations. The same method was applied to obtain the Jones matrix elements of a twisted nematic liquid crystal panel.
Effects of Current Modulation Conditions on the Chromaticity of Phosphor Converted (PC) White LEDs
Kim, Seungtaek ; Kim, Jongseok ; Kim, Hyungtae ; Kim, Yong-Kweon ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 449~456
DOI : 10.3807/JOSK.2012.16.4.449
For two well-known modulation methods, stepwise current modulation (SCM) and pulse width modulation (PWM), the effects of driving current modulation conditions on chromaticity were experimentally investigated in a white LED lighting system. For the experimental implementation of both SCM and PWM, a white LED lighting was fabricated using phosphor converted (PC) white light emitting diodes (LEDs) and a driving circuit module was developed. By using them, the variations of illuminance, color coordinates, and spectrum were evaluated under various forward current conditions. Through the analysis in color coordinates, yellow shift in SCM and blue shift in PWM were observed on chromaticity diagrams with increasing average driving current. In addition, in order to analyze color deviation quantitatively, color distance before and after current increase, and the correlated color temperature (CCT) were calculated. As a result, for the white LED lighting in both modulation conditions, the maximum difference in the calculated CCT was obtained close to 1000 K. It means that careful consideration is required to be taken in the design of illumination systems to avoid serious problems such industrial accidents.
Real-time Measurement of Full Field Retardation Near Quarter Wavelength
Liu, Longhai ; Zeng, Aijun ; Yuan, Qiao ; Zhu, Linglin ; Fang, Ruifang ; Huang, Huijie ;
Journal of the Optical Society of Korea, volume 16, issue 4, 2012, Pages 457~461
DOI : 10.3807/JOSK.2012.16.4.457
A real-time method to measure full field retardation near quarter wavelength is proposed. The circularly polarized beam passes through a sample with a large aperture. The measuring beam then goes through a quarter-wave plate and is then split by a Wollaston prism. An image with two sub-images is then detected by a high-speed image sensor. The full field retardation near quarter wavelength can be obtained in real time by processing the image. The measured retardation is independent of the fast axis angle of the sample and the fluctuation of the initial intensity. In experiments, a wedge waveplate is measured with different fast axis angle and initial intensity, and the full field retardations are acquired. The maximum and standard deviation of the full field retardation is
. The validity of the method is verified.