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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 15, Issue 4 - Dec 2011
Volume 15, Issue 3 - Sep 2011
Volume 15, Issue 2 - Jun 2011
Volume 15, Issue 1 - Mar 2011
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Numerical Modeling of Compression-Controlled Low-level Laser Probe for Increasing Photon Density in Soft Tissue
Kwon, Ki-Woon ; Son, Tae-Yoon ; Yeo, Chang-Min ; Jung, Byung-Jo ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 321~328
DOI : 10.3807/JOSK.2011.15.4.321
Various methods have been investigated to increase photon density in soft tissue, an important factor in low-level laser therapy. Previously we developed a compression-controlled low-level laser probe (CCLLP) utilizing mechanical negative compression, and experimentally verified its efficacy. In this study, we used Bezier curves to numerically simulate the skin deformation and photon density variation generated by the CCLLP. In addition, we numerically modeled changes in optical coefficients due to skin deformation using a linearization technique with appropriate parameterization. The simulated results were consistent with both human in vivo and porcine ex vivo experimental results, confirming the efficacy of the CCLLP.
A PDMS-Coated Optical Fiber Bragg Grating Sensor for Enhancing Temperature Sensitivity
Park, Chang-Sub ; Joo, Kyung-Il ; Kang, Shin-Won ; Kim, Hak-Rin ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 329~334
DOI : 10.3807/JOSK.2011.15.4.329
We proposed a poly-dimethylsiloxane (PDMS)-coated fiber Bragg grating (FBG) temperature sensor for enhancing temperature sensitivity. By embedding the bare FBG in a temperature-sensitive elastomeric polymer, the temperature sensitivity of the proposed structure could be effectively improved by 4.2 times higher than those of the conventional bare-type FBG sensors due to the high thermal expansion coefficient of the PDMS. We analyzed the temperature-sensitivity enhancement effect with the increased Bragg wavelength shift in our structure and dependence on the temperature sensitivity with respect to the cross-section area of the PDMS.
Coded Single Input Channel for Color Pattern Recognition in Joint Transform Correlator
Jeong, Man-Ho ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 335~339
DOI : 10.3807/JOSK.2011.15.4.335
Recently, we reported a single input channel joint transform correlator for the color pattern recognition which decomposes the input color image into three R, G, and B gray components and adds those components into a single gray image in the input plane. This technique has the merit of a single input channel instead of three input channels. However, we found this technique has some problems with discrimination impossibility in the case of a simple primary color pattern which results in the same gray level through the addition process. Thus, we propose a modified coding technique which selectively recombines the decomposed three R, G, and B gray components instead of the simple adding process. Simulated results show that the modified coding technique can accurately discriminate a variety of kinds of color images.
Airborne Infrared Scanning Imaging System with Rotating Drum for Fire Detection
Song, c ; Chang, Jun ; Cao, Jiao ; Zhang, Lifei ; Wen, Yao ; Wei, Aman ; Li, Jiang ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 340~344
DOI : 10.3807/JOSK.2011.15.4.340
Airborne infrared techniques have been used in wild land fire management for decades. This paper describes a kind of infrared scanning system based on a rotating drum with a tilted porthole underside the plane nose. This design increases the stability of the mechanism system, reduces air resistance and protects inner parts. Aberration characteristics of a tilted ellipsoid porthole are analyzed and an effective solution is invented which makes the system achieve
field of regard. The system's ultimate value of modulation transfer function is near the diffraction limit, which indicates that the performance of the rotating optical system meets the imaging requirements.
Three-dimensional Binocular Holographic Display Using Liquid Crystal Shutter
Kim, Hyun-Eui ; Kim, Hee-Seung ; Jeong, Kyeong-Min ; Park, Jae-Hyeung ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 345~351
DOI : 10.3807/JOSK.2011.15.4.345
We present a novel approach to the holographic three-dimensional display using a liquid crystal shutter for binocular display applications. One of the difficult problems in implementing a binocular holographic three-dimensional display is the extremely narrow viewing angle. This problem is attributed to the spatial light modulator pixel number which restricts the maximum spatial bandwidth of the spatial light modulator. In our proposed method, a beam splitter and liquid crystal shutter are used to present two holograms of a three-dimensional scene to the corresponding eyes. The combination of holographic display and liquid crystal shutter can overcome the problem of the extremely narrow viewing angle, presenting threedimensional images to both eyes with correct accommodation depth cues.
Dual-wavelength Digital Holography Microscope for BGA Measurement Using Partial Coherence Sources
Cho, Hyung-Jun ; Kim, Doo-Cheol ; Yu, Young-Hun ; Jung, Won-Ki ; Shin, Sang-Hoon ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 352~356
DOI : 10.3807/JOSK.2011.15.4.352
Dual-wavelength holography has a better axial range than single-wavelength holography, allowing unambiguous phase imaging. Partial coherence sources reduce coherent noise, resulting in improved reconstructed images. We measured a ball-grid array using dual-wavelength holography with partial coherence sources. This holography method is useful for measurement samples that exhibit coherence noise and have a step height larger than the single wavelength used in holography.
Distance Extraction by Means of Photon-Counting Passive Sensing Combined with Integral Imaging
Yeom, Seok-Won ; Woo, Yong-Hyen ; Baek, Won-Woo ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 357~361
DOI : 10.3807/JOSK.2011.15.4.357
Photon-counting sensing is a widely used technique for low-light-level imaging applications. This paper proposes a distance information extraction method with photon-counting passive sensing under low-lightlevel conditions. The photo-counting passive sensing combined with integral imaging generates a photon-limited elemental image array. Maximum-likelihood estimation (MLE) is used to reconstruct the photon-limited image at certain depth levels. The distance information is extracted at the depth level that minimizes the sum of the standard deviation of the corresponding photo-events in the elemental image array. Experimental and simulation results confirm that the proposed method can extract the distance information of the object under low-light-level conditions.
Effect of Laser Beam Trajectory on Donor Plate in Laser Induced Thermal Printing Process
Lee, Kwang-Won ; Lee, Si-Jin ; Kwon, Jin-Hyuk ; Yi, Jong-Hoon ; Park, Lee-Soon ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 362~367
DOI : 10.3807/JOSK.2011.15.4.362
) film, which was coated on a donor plate, was transferred to an organic light emitting diode (OLED) substrate with help of heat generated by a dithering laser beam. The laser beam was diffracted in an acousto-optic modulator (AOM), then focused on the laser-to-heat converting layer of the donor plate; the focused spot followed trajectories guided by rotation of a Galvano-mirror. Three different functional waveforms, sine wave, square wave, and saw tooth wave were applied to the AOM as modulation signal to generate the dithering beam. The fluorescence microscope images of the donor plate showed that the patterns of removed
film were affected considerably by the modulation waveforms and the phase difference between adjacent dithering beams. Further, the printed images of Alq3 film on the OLED substrate were different from the patterns of removed Alq3 film. Atomic force microscope images indicated that not only direct transfer but also deposition by sublimated vapor of Alq3 contributed to the pattern formation. Printed patterns affected considerably the electricity-to-light conversion characteristics of OLEDs. For uniform transfer, not only the phase relation of dithering beam lines but also adequate waveform were important.
Experimental Study on the Operation of a Keyhole-Shaped Lens in a Microcolumn
Oh, Tae-Sik ; Jin, Sang-Won ; Choi, Sang-Kuk ; Kim, Young-Chul ; Kim, Dae-Wook ; Ahn, Seung-Joon ; Lee, Young-Bok ; Kim, Ho-Seob ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 368~372
DOI : 10.3807/JOSK.2011.15.4.368
An advanced microcolumn is proposed which adopts a modified einzel lens structure. The newly designed einzel lens is composed of four electrodes. The two center electrodes are specially designed electrostatic quadrupole (EQ) einzel lenses having keyhole instead of circular apertures. We constructed the advanced microcolumn with the EQ-einzel lenses, and operated the newly designed microcolumn in single lens mode and double-lens mode. The preliminary results show that the EQ-einzel lens can improve the performance of the micro-column for large sample applications.
Optical Spectroscopic Analysis of Muscle Spasticity for Low-Level Laser Therapy (LLLT)
Lee, Yeon-Ui ; Lee, Sang-Kwan ; Youn, Jong-In ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 373~379
DOI : 10.3807/JOSK.2011.15.4.373
Current therapeutic methods for suppressing muscle spasticity are intensive functional training, surgery, or pharmacological interventions. However, these methods have not been fully supported by confirmed efficacy due to the aggravation of the muscle spasticity in some patients. In this study, a combined system was developed to treat with a low-level laser and to monitor the region of the treatment using an optical spectroscopic probe that measures oxygen saturation and deoxygenation during low-level laser therapy (LLLT). The evaluation of the wavelength dependence for LLLT was performed using a Monte Carlo simulation and the results showed that the greatest amount of heat generation was seen in the deep tissue at
= 830 nm. In the oxy- and deoxygenation measurements during and after the treatment, oxygen-Hb concentration was significantly increased in the laser-irradiated group when compared to the control group. These findings suggest that LLLT using
= 830 nm may be of benefit in accelerating recovery of muscle spasticity. The combined system that we have developed can monitor the physiological condition of muscle spasticity during the laser treatment in real time and may also be applied to various myotonia conditions such as muscle fatigue, back-pain treatment/monitoring, and ulcer due to paralysis.
Post-tuning of Sample Position in Common-path Swept-source Optical Coherence Tomography
Park, Jae-Seok ; Jeong, Myung-Yung ; Kim, Chang-Seok ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 380~385
DOI : 10.3807/JOSK.2011.15.4.380
Common-path interferometers are widely used for endoscopic optical coherence tomography (OCT) because an arbitrary arm length can be chosen for the endoscopic imaging probe. However, the scheme suffers from the limited range of the sample position distance from the end of the imaging probe because the position between the reference reflector and the sample is limited by the optical path-length difference (OPD) to induce an interference signal. In this study, we developed a novel method for compensating the arbitrary sample position in common-path swept-source OCT by adding an extra Mach-Zehnder interferometer in the post-path of the interfered optical signal. Theoretical analysis and an experimental demonstration of imaging depth tuning for the flexible sample position of an endoscopic OCT image are discussed. After post-tuning of sample position distance, the positioning limitation between the reference reflector and the sample can be solved for various sample positions over a range of 26 mm for the cross-sectional images of a fish eye sample.
Simple Spectral Calibration Method and Its Application Using an Index Array for Swept Source Optical Coherence Tomography
Jung, Un-Sang ; Cho, Nam-Hyun ; Kim, Su-Hwan ; Jeong, Hyo-Sang ; Kim, Jee-Hyun ; Ahn, Yeh-Chan ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 386~393
DOI : 10.3807/JOSK.2011.15.4.386
In this study, we report an effective k-domain linearization method with a pre-calibrated indexed look-up table. The method minimizes k-domain nonlinear characteristics of a swept source optical coherence tomography (SS-OCT) system by using two arrays, a sample position shift index and an intensity compensation array. Two arrays are generated from an interference pattern acquired by connecting a Fabry-Perot interferometer (FPI) and an optical spectrum analyzer (OSA) to the system. At real time imaging, the sample position is modified by location movement and intensity compensation with two arrays for linearity of wavenumber. As a result of evaluating point spread functions (PSFs), the signal to noise ratio (SNR) is increased by 9.7 dB. When applied to infrared (IR) sensing card imaging, the SNR is increased by 1.29 dB and the contrast noise ratio (CNR) value is increased by 1.44. The time required for the linearization and intensity compensation is 30 ms for a multi thread method using a central processing unit (CPU) compared to 0.8 ms for compute unified device architecture (CUDA) processing using a graphics processing unit (GPU). We verified that our linearization method is appropriate for applying real time imaging of SS-OCT.
Eight-axis-polishing Machine for Large Off-axis Aspheric Optics
Rhee, Hyug-Gyo ; Yang, Ho-Soon ; Moon, Il-Kweon ; Kihm, Hag-Yong ; Lee, Jae-Hyub ; Lee, Yun-Woo ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 394~397
DOI : 10.3807/JOSK.2011.15.4.394
For the purpose of fabricating off-axis aspheric optics, we propose an 8-axis-polishing machine combined with a testing tower whose height is up to 9 m. The proposed polishing machine was designed and analyzed by using a well-known finite element method. The eight axes of the machine have a synchronized motion generated by a computer, and each axis was calibrated by a heterodyne laser interferometer or an optical encoder. After calibration, the maximum positioning error of the machine was less than 2
within a whole 2 m
2 m area. A typical fabrication result of a
m concave mirror was also described in this manuscript.
Temperature Stabilization of Group Index in Silicon Slotted Photonic Crystal Waveguides
Aghababaeian, Hassan ; Vadjed-Samiei, Mohammad-Hashem ; Granpayeh, Nosrat ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 398~402
DOI : 10.3807/JOSK.2011.15.4.398
In this paper, we have proposed a principle to design wideband, low dispersion and temperature stabilized slow light structure in slotted photonic crystal waveguide (SPCW). The infiltration of the silicon photonic crystal with polymer will enhance the slow light and increase the group index, whereas the different signs of thermo-optic coefficients of polymer and silicon make the proposed structure stable on temperature variation over
and improves the group index-bandwidth products of the designed structure. The SPCW structure is modified to maximize the slow light effect and minimize the dependence of the group index and hence the group velocity dispersion to temperature.
Beam Splitting by the Use of Waveguide Airy Beams
Kim, Kyoung-Youm ; Kim, Sae-Hwa ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 403~406
DOI : 10.3807/JOSK.2011.15.4.403
Here we report Airy beams coupled with waveguide modes. These waveguide Airy (WAiry) beams propagate through layered planar structures inheriting the characteristics of waveguide modes as well as those of Airy beams, such as diffraction-free and accelerating features. In particular, we focus on the WAiry beams associated with backward waveguide modes, showing that the backward feature can alter the trajectories of the WAiry beams significantly. Based on this, we propose a new scheme of waveguide-type polarization/power beam splitters.
Cooperative Spontaneous Emission from Nanocrystals to a Surface Plasmon Polariton in a Metallic Nanowire
Lee, Joong-Hag ; Hong, Suc-Kyoung ; Nam, Seog-Woo ; Kim, Seog-Seong ;
Journal of the Optical Society of Korea, volume 15, issue 4, 2011, Pages 407~414
DOI : 10.3807/JOSK.2011.15.4.407
We analyze the cooperative spontaneous emission of optically excited nanocrystals into surface plasmon polaritons propagating on the surface of a cylindrical metallic nanowire. The spontaneous emission probability of the nanocrystals is obtained by perturbative expansions with and without dipole-dipole interaction among nanocrystals in order to see the cooperative effects. The spontaneous emission probability depends on the radial and axial distributions, as well as on the dipolar orientation of nanocrystals. It is shown that the spontaneous emission probability is strongly influenced by dipole-dipole interaction, axial distribution, and dipolar orientation of nanocrystals for closely spaced nanocrystals.