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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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Coherence Studies of Photons Emitted from a Single Terrylene Molecule Using Michelson and Young’s Interferometers
Yoon, Seung-Jin ; Trinh, Cong Tai ; Lee, Kwang-Geol ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 555~559
DOI : 10.3807/JOSK.2015.19.6.555
Coherence length (time) is a key parameter in many classical and quantum optical applications. Two interferometers – Michelson and Young’s double-slit – are used to characterize the temporal coherence of single photons emitted from single terrylene molecules. For quantitative analysis, a dispersion-related distortion in the interference pattern of a Michelson interferometer is carefully corrected by a simple dispersion compensation. Additionally, it has been demonstrated that Young’s interferometer can be used in temporal coherence studies at the single photon level with high accuracy. The pros and cons of the two systems are discussed. The measured coherence lengths in the two systems are consistent with one another under the self-interference interpretations.
Characteristics of THz Pulse Propagation on Teflon Covered Two-Wire Lines
Jo, Jeong Sang ; Jeon, Tae-In ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 560~565
DOI : 10.3807/JOSK.2015.19.6.560
We report efficient direct coupling of THz dipole antenna pulses onto air spaced two-wire transmission lines and Teflon covered two-wire lines. The air spaced two-wire lines show TEM mode propagation with very small group velocity dispersion (GVD) and relatively low attenuation. The Teflon covered two-wire lines showed comparatively much higher attenuation and GVD. However, the Teflon covered two-wire lines show a very good guiding property when the lines are curved. Although the lines are circled only 5.0 cm in diameter, there is no additional attenuation compared to straight the lines.
Highly Efficient Trans-Reflective Color Filters Incorporating TiO
Shrestha, Vivek Raj ; Park, Chul-Soon ; Koirala, Ishwor ; Lee, Sang-Shin ; Choi, Duk-Yong ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 566~574
DOI : 10.3807/JOSK.2015.19.6.566
We report for the first time highly efficient trans-reflective color filters capable of demonstrating coloration in both transmission and reflection modes by taking advantage of a multilayer stack consisting of MgF
used respectively as the low and high index materials. In order to enable such trans-reflective performance, securing an optimal stop band assuming an appropriate bandwidth within the visible regime is pivotal, which was realized by tailoring the thicknesses and the numbers of TiO
bi-layers. Three devices were designed through rigorous simulations and developed via e-beam evaporation to demonstrate vivid blue, green, and red colors in the reflection mode, and yellow, magenta, and cyan colors in the transmission mode, featuring an enhanced efficiency exceeding 90% under normal incidence. The color performance of the filters was examined by referring to the chromaticity coordinates of the transmission and reflection spectra, alongside photographed color images. The dependence of the performance on the angle of incidence was explored with respect to incident polarization, indicating that a transmission surpassing 60% could be stably maintained up to an angle of 75°. Polarization independent transfer characteristics were especially achieved for the normal incidence. The proposed devices may be readily extended to other spectral regimes by adjusting the thicknesses of the films.
Dynamic Magnetic Field Measurement in the Air Gap of Magnetic Bearings Based on FBG-GMM Sensor
Jiayi, Liu ; Zude, Zhou ; Guoping, Ding ; Huaqiang, Wang ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 575~585
DOI : 10.3807/JOSK.2015.19.6.575
Magnetic field in magnetic bearings is the physical medium to realize magnetic levitation, the distribution of the magnetic field determines the operating performance of magnetic bearings. In this paper, a thin-slice Fiber Bragg Grating-Giant Magnetostrictive Material magnetic sensor used for the air gap of magnetic bearings was proposed and tested in the condition of dynamic magnetic field. The static property of the sensor was calibrated and a polynomial curve was fitted to describe the performance of the sensor. Measurement of dynamic magnetic field with different frequencies in magnetic bearings was implemented. Comparing with the finite element simulations, the results showed the DC component of the magnetic field was detected by the sensor and error was less than 5.87%.
Indoor Positioning System using LED Lights and a Dual Image Sensor
Moon, Myoung-geun ; Choi, Su-il ; Park, Jaehyung ; Kim, Jin Young ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 586~591
DOI : 10.3807/JOSK.2015.19.6.586
In recent years, along with the rapid development of LED technology, indoor positioning systems based on visible light communication (VLC) have been researched. In this paper, we propose an accurate indoor positioning method using white-light LEDs and a dual image sensor. Indoor LED lights are located at the ceiling in a room and broadcast information on their positions using VLC technology. A mobile device with a dual image sensor receives LED position information by VLC and estimates its position and azimuth angle. Simulation and experimental results are given to show the performance of the proposed indoor positioning system.
Optical Implementation of Asymmetric Cryptosystem Combined with D-H Secret Key Sharing and Triple DES
Jeon, Seok Hee ; Gil, Sang Keun ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 592~603
DOI : 10.3807/JOSK.2015.19.6.592
In this paper, an optical implementation of a novel asymmetrical cryptosystem combined with D-H secret key sharing and triple DES is proposed. The proposed optical cryptosystem is realized by performing free-space interconnected optical logic operations such as AND, OR and XOR which are implemented in Mach-Zehnder type interferometer architecture. The advantage of the proposed optical architecture provides dual outputs simultaneously, and the encryption optical setup can be used as decryption optical setup only by changing the inputs of SLMs. The proposed cryptosystem can provide higher security strength than the conventional electronic algorithm, because the proposed method uses 2-D array data, which can increase the key length surprisingly and uses 3DES algorithm, which protects against “meet in the middle” attacks. Another advantage of the proposed asymmetrical cryptosystem is that it is free to change the user’s two private random numbers in generating the public keys at any time. Numerical simulation and performance analysis verify that the proposed asymmetric cryptosystem is effective and robust against attacks for the asymmetrical cipher system.
Off-axis Two-mirror System with Wide Field of View Based on Diffractive Mirror
Meng, Qingyu ; Dong, Jihong ; Wang, Dong ; Liang, Wenjing ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 604~613
DOI : 10.3807/JOSK.2015.19.6.604
An unobstructed off-axis two-mirror system is presented in this paper. First a suitable initial configuration is established based on third-order aberration theory. In order to achieve a wide field of view (FOV) with high image quality , the diffractive mirror is adopted in the two-mirror system to increase the optimization freedom and the aberration relationship between diffractive phase coefficients and Zernike coefficients is derived. Furthermore, a complete comparison design example with a focal length of 1200 mm, F-number of 12, and FOV of 40° × 2° is given to verify the aberration correction ability of the diffractive mirror. The system average wavefront error is 0.007 λ (λ=0.6328 μm) developed from 0.061 λ when the system didn’t adopt the diffractive mirror. In this system the phase modulation function of the diffractive mirror is established as an even function of x, so we could obtain a symmetrical imaging quality about the tangential plane, and the symmetric aberration performance also brings considerable convenience to alignment and testing for the system.
Design of a See-Through Head-Mounted Display with a Freeform Surface
Wang, Junhua ; Liang, Yuechao ; Xu, Min ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 614~618
DOI : 10.3807/JOSK.2015.19.6.614
This paper described an off-axis head-mounted display system. It is composed of a 7-piece coaxial relay lens group and a freeform surface combiner. This configuration has a simple structure and a wide field of view (FOV). In this design, a freeform surface is chosen as the combiner, to simplify the structure and attain good image quality. We generated this freeform surface by considering both coordinates and normals of discrete data points. Moreover, we realize a coaxial structure in the relay lens group, which is compact and benefits from a loose tolerance requirement. The HMD system we finally realized has a 40° × 30° FOV and 15-mm exit pupil diameter.
Deterministic Estimation of Stripe Type Defects and Reconstruction of Mask Pattern in L/S Type Mask Inspection
Kim, Wooshik ; Park, Min-Chul ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 619~628
DOI : 10.3807/JOSK.2015.19.6.619
In this paper, we consider a method for estimating a stripe-type defect and the reconstruction of a defect-free L/S type mask used in lithography. Comparing diffraction patterns of defected and defect-free masks, we derive equations for the estimation of the location and size of the defect. We construct an analytical model for this problem and derive closed form equations to determine the location and size using phase retrieval problem solving techniques. Consequently, we develop an algorithm that determines a defect-free mask pattern. An example shows the validity of the equations.
Optical Design and Fabrication of a Large Telephoto Zoom Lens with Fixed f/2.8 and Light Autofocus Lens
Ryu, Jae Myung ; Gang, Geon Mo ; Lee, Hyuck Ki ; Lee, Ki Woo ; Heu, Min ; Jo, Jae Heung ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 629~637
DOI : 10.3807/JOSK.2015.19.6.629
Compact system cameras (CSCs) are commonly used nowadays and feature enhanced video functions and thin yet light interchangeable lenses. They differ from digital single-lens reflex (DSLR) cameras in their lack of mirror boxes. CSCs, however, have autofocus (AF) speeds lower than those of conventional DSLRs, requiring weight reduction of their AF groups. To ensure the marketability of large telephoto zoom lenses with fixed f/2.8 regardless of field angle variation, in particular, light weight AF groups are essential. In this paper, we introduce a paraxial optical design method and present a new, large, telephoto zoom lens with f/2.8 regardless of the field angle variation, plus a lightweight AF group consisting of only one lens. Using the basic paraxial optical design and optimization methods, we fabricated a new and lighter zoom lens system, including a single-lens, lightweight AF group with almost the same performance.
A Simple Method for Determining Focal Distances Using Talbot Self-Images
Spires, Oliver ; Sasian, Jose ; Lee, Sukmock ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 638~642
DOI : 10.3807/JOSK.2015.19.6.638
We present a simple method to determine the focal distances of lenses with the Talbot self-images. This method uses only one grating, and a priori knowledge of the period of the grating is replaced with a linear relation between the (de)magnified periods of the Talbot images and the lens-to-grating distance. A thick lens whose effective focal length is 500 mm was used to validate the method, and the focal distance of the converging beam was determined with the difference of 0.15% for the nominal focal distance of 521.9 mm. The determined period of the grating with the difference of 0.2% also supports the validation.
Mathematical Morphology Guided Automatic Unwrapping Isoclinic Phase Map in White Light Photoelasticity
Liu, Xiaomeng ; Dai, Shuguang ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 643~648
DOI : 10.3807/JOSK.2015.19.6.643
By comparing the results calculated by atan() and atan2() functions, the correctly estimated region of isoclinic phase map is determined using morphological techniques. The isoclinic phase map is automatically unwrapped in the true phase range -π/2 to π/2. Demonstrations of the method on a disc and a ring under diametral compression are performed. Test results compare well with the theoretical results. Furthermore, the influences of principal stress direction and the range of isoclinic phase upon stress separation are discussed.
Surface Color Measurement Uncertainties
Hwang, Jisoo ; Jeong, Ki-Lyong ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 649~657
DOI : 10.3807/JOSK.2015.19.6.649
We present a surface color measurement including quantities of surface color, methods, and uncertainty evaluation. Based on a relation between spectral reflectance and surface color, we study how an uncertainty of spectral reflectance propagates to surface color. In analyzing the uncertainty propagation, we divide the uncertainty into uncorrelated components, fully correlated components, and correlated components with spectrally varying correlations. As an experimental example, we perform spectro-reflectometric measurements for ceramic color plates. With measured spectral reflectance and its uncertainty evaluation, we determine surface color and analyze uncertainties of the ceramic color plates.
Field-Curvature Correction According to the Curvature of a CMOS Image-Sensor Using Air-Gap Optimization
Kwon, Jong-Hoon ; Rhee, Hyug-Gyo ; Ghim, Young-Sik ; Lee, Yun-Woo ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 658~664
DOI : 10.3807/JOSK.2015.19.6.658
Lens designers generally refer to flat image fields and attempt to minimize the field curvature. Present-day CMOS image sensors for mobile phone cameras, however, are not flat, but curved. Sometimes it is necessary to generate an intentional field curvature according to the degree and direction of the CMOS image-sensor’s curvature. This paper presents the degree of curvature of a CMOS image sensor measured using an interferometer, and proposes an effective compensation method that minimizes the net field curvature through optimizing the air gap between lens elements, which is demonstrated using simulations and experiments.
Ultrathin Metamaterial for Polarization Independent Perfect Absorption and Band-pass Filter
Zhang, Xu ; Gong, Zhijie ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 665~672
DOI : 10.3807/JOSK.2015.19.6.665
We demonstrate an ultrathin metamaterial for polarization independent perfect absorption as well as a band-pass filter (BPF) which works at a higher frequency band compared to the perfect absorption band. The planar metamaterial is comprised of three layers, symmetric split ring resonators (SSRRs) at the front and structured ground plane (SGP) at the back separated by a dielectric layer. The perfect metamaterial absorber (MA) can realize near 100% absorption due to high electromagnetic losses from the electric and/or magnetic resonances within a certain frequency band. The thickness of the structure is only 1/28 of the maximum absorption wavelength.
Dual-band Frequency Selective Surface Bandpass Filters in Terahertz Band
Qi, Limei ; Li, Chao ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 673~678
DOI : 10.3807/JOSK.2015.19.6.673
Terahertz dual-band frequency selective surface filters made by perforating two different rectangular holes in molybdenum have been designed, fabricated and measured. Physical mechanisms of the dual-band resonant responses are clarified by three differently configured filters and the electric field distribution diagrams. The design process is straightforward and simple according to the physical concept and some formulas. Due to the weak coupling between the two neighboring rectangle holes with different sizes in the unit cell, good dual-band frequency selectivity performance can be easily achieved both in the lower and higher bands by tuning dimensions of the two rectangular holes. Three samples are fabricated, and their dual-band characteristics have been demonstrated by a THz time-domain spectroscopy system. Different from most commonly used metal-dielectric structure or metal-dielectric-metal sandwiched filters, the designed dual-band filters have advantages of easy fabrication and low cost, the encouraging results afforded by these filters could find their applications in dual-band sensors, THz communication systems and other emerging THz technologies.
Design of a Tele-centric Wide Field Lens with High Relative Illumination and Low Distortion Using Third-order Aberration Analysis
Kim, Kae-Hong ; Kim, Yeong-Sik ; Park, Sung-Chan ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 679~686
DOI : 10.3807/JOSK.2015.19.6.679
This paper presents a design method for improving the low relative illumination and large distortion due to widening the field of a system. A tele-centric optical system in image space was suggested to increase the relative illumination. Through the analyses of the third-order aberrations affected by introducing aspherical surfaces, we have proposed a method to determine analytically what surface should be aspheric to correct each aberration effectively. By utilizing this method to design a wide field lens, a tele-centric wide field lens with f-number of F/2.0 was obtained. Even though the field angle is 120 degrees, it has a very low distortion less than -2% and high relative illumination more than 73.7%. In conclusion, this analytic method for selecting aspherical surfaces is expected to serve as a useful way to find design solutions.
Properties of Defective Regions Observed by Photoluminescence Imaging for GaN-Based Light-Emitting Diode Epi-Wafers
Kim, Jongseok ; Kim, HyungTae ; Kim, Seungtaek ; Jeong, Hoon ; Cho, In-Sung ; Noh, Min Soo ; Jung, Hyundon ; Jin, Kyung Chan ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 687~694
DOI : 10.3807/JOSK.2015.19.6.687
A photoluminescence (PL) imaging method using a vision camera was employed to inspect InGaN/GaN quantum-well light-emitting diode (LED) epi-wafers. The PL image revealed dark spot defective regions (DSDRs) as well as a spatial map of integrated PL intensity of the epi-wafer. The Shockley-Read-Hall (SRH) nonradiative recombination coefficient increased with the size of the DSDRs. The high nonradiative recombination rates of the DSDRs resulted in degradation of the optical properties of the LED chips fabricated at the defective regions. Abnormal current-voltage characteristics with large forward leakages were also observed for LED chips with DSDRs, which could be due to parallel resistances bypassing the junction and/or tunneling through defects in the active region. It was found that the SRH nonradiative recombination process was dominant in the voltage range where the forward leakage by tunneling was observed. The results indicated that the DSDRs observed by PL imaging of LED epi-wafers were high density SRH nonradiative recombination centers which could affect the optical and electrical properties of the LED chips, and PL imaging can be an inspection method for evaluation of the epi-wafers and estimation of properties of the LED chips before fabrication.
Development of High Spectral Resolution Lidar System for Measuring Aerosol and Cloud
Zhao, Ming ; Xie, Chen-Bo ; Zhong, Zhi-Qing ; Wang, Bang-Xin ; Wang, Zhen-Zhu ; Dai, Pang-Da ; Shang, Zhen ; Tan, Min ; Liu, Dong ; Wang, Ying-Jian ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 695~699
DOI : 10.3807/JOSK.2015.19.6.695
A high spectral resolution lidar (HSRL) system based on injection-seeded Nd:YAG laser and iodine absorption filter has been developed for the quantitative measurement of aerosol and cloud. The laser frequency is stabilized at 80 MHz by a frequency locking system and the absorption line of iodine cell is selected at the 1111 line with 2 GHz width. The observations show that the HSRL can provide vertical profiles of particle extinction coefficient, backscattering coefficient and lidar ratio for cloud and aerosol up to 12 km altitude, simultaneously. For the measured cases, the lidar ratios are 10~20 sr for cloud, 28~37 sr for dust, and 58~70 sr for urban pollution aerosol. It reveals the potential of HSRL to distinguish the type of aerosol and cloud. Time series measurements are given and demonstrate that the HSRL has ability to continuously observe the aerosol and cloud for day and night.
An Array-Type RGB Sensor for Precision Measurement of pH
Kim, Ji-Sun ; Oh, Han-Byeol ; Kim, A-Hee ; Kim, Jun-Sik ; Lee, Eun-Suk ; Goh, Bong-Jun ; Choi, Ju-Hyeon ; Shin, Ye-Ji ; Baek, Jin-Young ; Lee, Ki Sung ; Jun, Jae-Hoon ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 700~704
DOI : 10.3807/JOSK.2015.19.6.700
As pH is a widely used index in chemical, medical, and environmental applications, research on pH sensors has been active in recent years. This study obtained RGB values by measuring the reflected light from a liquid sample to detect fine changes in pH, and performed mathematical modeling to investigate the relationship between the detected optical signal and pH value. Also, the trends in pH changes were easily identified by analyzing RGB values and displaying them in the color coordinate for easy visualization of data. This method implemented a user-friendly system that can measure and analyze in real time. This system can be used in many fields such as genetic engineering, environmental engineering, and clinical engineering, because it not only can measure pH but also replaces a colorimeter or turbidimeter.
Opto-Electrochemical Sensing Device Based on Long-Period Grating Coated with Boron-Doped Diamond Thin Film
Bogdanowicz, Robert ; Sobaszek, Michał ; Ficek, Mateusz ; Gnyba, Marcin ; Ryl, Jacek ; Siuzdak, Katarzyna ; Bock, Wojtek J. ; Smietana, Mateusz ;
Journal of the Optical Society of Korea, volume 19, issue 6, 2015, Pages 705~710
DOI : 10.3807/JOSK.2015.19.6.705
The fabrication process of thin boron-doped nanocrystalline diamond (B-NCD) microelectrodes on fused silica single mode optical fiber cladding has been investigated. The B-NCD films were deposited on the fibers using Microwave Plasma Assisted Chemical Vapor Deposition (MW PA CVD) at glass substrate temperature of 475 ℃. We have obtained homogenous, continuous and polycrystalline surface morphology with high sp
content in B-NCD films and mean grain size in the range of 100-250 nm. The films deposited on the glass reference samples exhibit high refractive index (n=2.05 at λ=550 nm) and low extinction coefficient. Furthermore, cyclic voltammograms (CV) were recorded to determine the electrochemical window and reaction reversibility at the B-NCD fiber-based electrode. CV measurements in aqueous media consisting of 5 mM K
] in 0.5 M Na
demonstrated a width of the electrochemical window up to 1.03 V and relatively fast kinetics expressed by a redox peak splitting below 500 mV. Moreover, thanks to high-n B-NCD overlay, the coated fibers can be also used for enhancing the sensitivity of long-period gratings (LPGs) induced in the fiber. The LPG is capable of measuring variations in refractive index of the surrounding liquid by tracing the shift in resonance appearing in the transmitted spectrum. Possible combined CV and LPG-based measurements are discussed in this work.