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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 20, Issue 6 - Dec 2016
Volume 20, Issue 5 - Oct 2016
Volume 20, Issue 4 - Aug 2016
Volume 20, Issue 3 - Jun 2016
Volume 20, Issue 2 - Apr 2016
Volume 20, Issue 1 - Feb 2016
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OATM/WDM Optical Access Network Using Header Decoder-Based Router for Next-Generation Communications
Park, Kihwan ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 335~342
DOI : 10.3807/JOSK.2016.20.3.335
We demonstrate an optical asynchronous transfer mode/wavelength division multiplexing (OATM/WDM) optical access network, using a router based on an optical header decoder to conduct next-generation communications. The router consists of a decoder or hardware analysis processing of the header bit and switches. The router in the OATM/WDM optical access network is a key technology by which to satisfy subscribers’ requests, including reliability, cost efficiency, high speed, large-capacity transmission, and elevated information security. In this study, we carry out experiments in which a header decoder delivers to 16 and 32 subscribers with a single wavelength in the router. These experiments confirm the decoder’s successful operation via hardware using 4 and 5 header bits. We propose that this system may significantly contribute toward the realization of an optical access network that provides high-quality service to subscribers of next-generation communications.
Asymmetric Multiple-Image Encryption Based on Octonion Fresnel Transform and Sine Logistic Modulation Map
Li, Jianzhong ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 341~357
DOI : 10.3807/JOSK.2016.20.3.341
A novel asymmetric multiple-image encryption method using an octonion Fresnel transform (OFST) and a two-dimensional Sine Logistic modulation map (2D-SLMM) is presented. First, a new multiple-image information processing tool termed the octonion Fresneltransform is proposed, and then an efficient method to calculate the OFST of an octonion matrix is developed. Subsequently this tool is applied to process multiple plaintext images, which are represented by octonion algebra, holistically in a vector manner. The complex amplitude, formed from the components of the OFST-transformed original images and modulated by a random phase mask (RPM), is used to derive the ciphertext image by employing an amplitude- and phase-truncation approach in the Fresnel domain. To avoid sending whole RPMs to the receiver side for decryption, a random phase mask generation method based on SLMM, in which only the initial parameters of the chaotic function are needed to generate the RPMs, is designed. To enhance security, the ciphertext and two decryption keys produced in the encryption procedure are permuted by the proposed SLMM-based scrambling method. Numerical simulations have been carried out to demonstrate the proposed scheme`s validity, high security, and high resistance to various attacks.
Optical Encryption of a Binary Image by Phase Modulation of the Wavefront
Song, Jaehun ; Moon, Inkyu ; Lee, Yeonho ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 358~362
DOI : 10.3807/JOSK.2016.20.3.358
We present a new scheme for optical encryption of a binary image. In our method, the original binary data page is first divided into two identical pages. In each data page, the “on” and “off” pixels are represented by two discrete phases that are 90° apart. The first page corresponds to the phase conjugation of the second page, and vice versa. In addition, the wavefront of the two data pages is changed simultaneously from planar to spherical, for better encryption. The wavefront modification is represented by an extra phase shift, which is a function of position on the wavefront. In this way the two separate pages are both encrypted, and therefore the pages cannot be distinguished in a CCD. If the first page is used as an encrypted data page, then the second page is used as the decryption key, and vice versa. The decryption can be done by simply combining the two encrypted data pages. It is shown in our experiment that encryption and decryption can be fully accomplished in the optical domain.
Resolution Enhanced Computational Integral Imaging Reconstruction by Using Boundary Folding Mirrors
Piao, Yongri ; Xing, Luyan ; Zhang, Miao ; Lee, Min-Chul ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 363~367
DOI : 10.3807/JOSK.2016.20.3.363
In this paper, we present a resolution-enhanced computational integral imaging reconstruction method by using boundary folding mirrors. In the proposed method, to improve the resolution of the computationally reconstructed 3D images, the direct and reflected light information of the 3D objects through a lenslet array with boundary folding mirrors is recorded as a combined elemental image array. Then, the ray tracing method is employed to synthesize the regular elemental image array by using a combined elemental image array. From the experimental results, we can verify that the proposed method can improve the visual quality of the computationally reconstructed 3D images.
Kalman Filter Based Optimal Controllers in Free Space Optics Communication
Li, Zhaokun ; Zhao, Xiaohui ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 368~380
DOI : 10.3807/JOSK.2016.20.3.368
There is no doubt that adaptive optics (AO) is the most promising method to compensate wavefront disturbance in free space optics communication (FSO). In order to improve the performance of the AO system described by discrete-time linear system model with time-delay and implicit phase turbulent model, new controllers based on a Kalman filter and its extensions are proposed. Based on the standard Kalman filter, we propose a fading memory filter to deal with the ruleless strong interference; sequential and U-D filters are applied to reduce implementation complexity for the embedded controllers. Theoretical analysis and the numerical simulations show that the proposed fading memory filter can upgrade the performance for AO systems in consideration of the unforeseen strong pulse interference, and the sequential and U-D filters perform well compared with a Kalman filter.
Measurement of the Modulation Transfer Function of Infrared Imaging System by Modified Slant Edge Method
Li, Hang ; Yan, Changxiang ; Shao, Jianbing ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 381~388
DOI : 10.3807/JOSK.2016.20.3.381
The performance of a staring infrared imaging system can be characterized based on estimating the modulation transfer function (MTF). The slant edge method is a widely used MTF estimation method, which can effectively solve the aliasing problem caused by the discrete undersampling of the infrared focal plane array. However, the traditional slant edge method has some limitations such as the low precision of the edge angle extraction and using the approximate function to fit the edge spread function (ESF), which affects the accuracy of the MTF estimation. In this paper, we propose a modified slant edge method, including an edge angle extraction method that can improve the precision of the edge angle extraction and an ESF fitting algorithm which is based on the transfer function model of the imaging system, to enhance the accuracy of the MTF estimation. This modified slant edge method presents higher estimation accuracy and better immunity to noise and edge angle than other traditional methods, which is demonstrated by the simulation and application experiments operated in our study.
Integrated Optimization Design of Carbon Fiber Composite Framework for Small Lightweight Space Camera
Yang, Shuai ; Sha, Wei ; Chen, Changzheng ; Zhang, Xingxiang ; Ren, Jianyue ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 389~395
DOI : 10.3807/JOSK.2016.20.3.389
A Carbon Fiber Composite (CFC) framework was designed for a small lightweight space camera. According to the distribution characteristics of each optical element in the optical system, CFC (M40J) was chosen to accomplish the design of the framework. TC4 embedded parts were used to solve the low accuracy of the CFC framework interface problem. An integrated optimization method and the optimization strategy which combined a genetic global optimization algorithm with a downhill simplex local optimization algorithm were adopted to optimize the structure parameters of the framework. After optimization, the total weight of the CFC framework and the TC4 embedded parts is 15.6 kg, accounting for only 18.4% that of the camera. The first order frequency of the camera reaches 104.8 Hz. Finally, a mechanical environment test was performed, and the result demonstrates that the first order frequency of the camera is 102 Hz, which is consistent with the simulation result. It further verifies the rationality and correctness of the optimization result. The integrated optimization method mentioned in this paper can be applied to the structure design of other space cameras, which can greatly improve the structure design efficiency.
Use of Speckle Pattern for Monitoring Thermal Energy Behavior of Battery Cathode
Kim, Byungwhan ; Jang, Junyoung ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 396~400
DOI : 10.3807/JOSK.2016.20.3.396
Laser speckle patterns were used to monitor variations of thermal voltages of a cathode during a battery discharge. Discharge voltages measured with an oscilloscope were utilized as a figure of merit of thermal voltages in Zn metal. Using an optical imaging system, speckle patterns were taken for zinc metal surface over a time period of 3 minutes. Pixel sum distribution functions (PSDFs) were extracted from speckle patterns. Accumulated pixel sums quantified from PSDFs over an optimized grayscale range strongly correlated with discharge voltages. This suggested that dark matter or particles may have the capability of both absorbing and radiating thermal energies simultaneously. The black body-like properties were able to be validated by identifying coincidences with distinct features of a black body spectrum. The pixels belonging to the grayscale range were confirmed to represent dark matter of a speckle pattern. It was clear that dark matter was part of surface plasmon carriers. The proposed sensing system can be applied to monitor thermal energy variations in any material.
Performance Enhancement of Cavity Assisted Photonic Crystal De-Multiplexerin Slow Light Regime
Vadjed-Samiei, Mohammad-Hashem ; Aghababaeian, Hassan ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 401~406
DOI : 10.3807/JOSK.2016.20.3.401
This study first proposes a new version of a photonic crystal based de-multiplexer operating under the slow light regime, secondly analyses the structure numerically to demonstrate de-multiplexing operation and finally studies the impact of light speed on the performance of the proposed structure. The operation wavelength is 1.55 µm. The study indicates that, by adjusting the speed of light, around 0.1C, in the main waveguide and in the output channels’ waveguides, an enhancement in the performance of the de-multiplexer will be gained.
Analysis of the Square Beam Energy Efficiency of a Homogenizer Near the Target for Laser Shock Peening
Kim, Taeshin ; Hwang, Seungjin ; Hong, Kyung Hee ; Yu, Tae Jun ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 407~412
DOI : 10.3807/JOSK.2016.20.3.407
We analyzed through numerical simulations the properties of a square beam homogenizer near the target for laser shock peening. The efficiency was calculated near the target by considering the plasma threshold of the metals. We defined the depth of focus of the square beam homogenizer with a given efficiency near the target. Then, we found the relationship between the depth of focus for the laser shock peening and four main parameters of the square beam homogenizer: the plasma threshold of the metal, the number of lenslets in the array-lens, the focal length of the condenser lens and the input beam size.
Lens Design of Camera through Optimization of the Third Order Seidel Aberration and Statistical Tolerance Analysis
Lee, Kyutae ; Kim, Young-Joo ; Kim, Youngwoon ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 413~426
DOI : 10.3807/JOSK.2016.20.3.413
There has been much advancement in the field of aerial cameras for geographical features with the help of drones, image processing power and computer aided optical programs. In this study, we propose a new optical lens design technique which minimizes the amount of ‘the third order Seidel aberration’ for enhancing MTF. In addition, we suggest a new optical lens design which stabilizes the mass-production yield through R.S.M and has robustness secure through the Taguchi method. Eventually, the image processing algorithm of stereo matching is implemented in order to evaluate whether the proposed lens design result meets adequate specifications for the use of dual aerial photographs or not. This paper provides good guidance for the optical design by development of experiments.
Effect of the Liquid Density Difference on Interface Shape of Double-Liquid Lens
Kong, Meimei ; Zhu, Lingfeng ; Chen, Dan ; Liang, Zhongcheng ; Zhao, Rui ; Xu, Enming ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 427~430
DOI : 10.3807/JOSK.2016.20.3.427
The effect of the liquid density difference on interface shape of a double-liquid lens is analyzed in detail. The expressions of interface shape of two liquids with liquid density difference are analyzed and fitted with “even asphere”. The imaging analysis of the aspheric interface shape of a double-liquid lens is presented. The results show that the density difference of two liquids can cause the interface to be an aspheric surface, which can improve the image quality of a double-liquid lens. The result provides a new selection for the related further research and a wider application field for liquid lenses.
High-precision THz Dielectric Spectroscopy of Tris-HCl Buffer
Lee, Soonsung ; Kang, Hyeona ; Do, Youngwoong ; Lee, Gyuseok ; Kim, Jinwoo ; Han, Haewook ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 431~434
DOI : 10.3807/JOSK.2016.20.3.431
Tris-HCl buffer solution is extensively used in biochemistry and molecular biology to maintain a stable pH for biomolecules such as nucleic acids and proteins. Here we report on the high-precision THz dielectric spectroscopy of a 10 mM Tris-HCl buffer. Using a double Debye model, including conductivity of ionic species, we measured the complex dielectric functions of Tris-HCl buffer. The fast relaxation time of water molecules in Tris-HCl buffer is ~20% longer than that in pure water while the slow relaxation time changes little. This means that the reorientation dynamics of Tris-HCl buffer with such a low Tris concentration is quite different from that of pure water.
Simple Autocorrelation Measurement by Using a GaP Photoconductive Detector
Shin, Seong-Il ; Lim, Yong-Sik ;
Journal of the Optical Society of Korea, volume 20, issue 3, 2016, Pages 435~440
DOI : 10.3807/JOSK.2016.20.3.435
We developed a simple and real-time readout autocorrelator for several tens and sub-10fs pulses, based on the two photon absorption phenomena of a commercial GaP photodetector including a transimpedance amplifier. With a suitable gain adjustment, we demonstrated that the interferometric autocorrelation for sub-nJ pulses delivered as a high output voltage as to resolve all fringes in an autocorrelation trace with features of low noise and a low offset voltage. By fitting the measured quadratic power dependence of output voltages, we obtained the quantum efficiency of TPA for the GaP detector comparable with those of a GaAsP diode and an SHG with a thin BBO crystal. The autocorrelator of a TPA based GaP photodetector is highly suitable for sensitively measuring a few cycle pulses with a broad spectral distribution from 600 nm to 1100 nm.