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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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Performance Comparison of Two Types of Silicon Avalanche Photodetectors Based on N-well/P-substrate and P
/N-well Junctions Fabricated With Standard CMOS Technology
Lee, Myung-Jae ; Choi, Woo-Young ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 1~3
DOI : 10.3807/JOSK.2011.15.1.001
We characterize and analyze silicon avalanche photodetectors (APDs) fabricated with standard complementary metal-oxide-semiconductor (CMOS) technology. Current characteristics, responsivity, avalanche gain, and photodetection bandwidth of CMOS-APDs based on two types of PN junctions, N-well/P-substrate and
/N-well junctions, are compared and analyzed. It is demonstrated that the CMOS-APD using the
/N-well junction has higher responsivity as well as higher photodetection bandwidth than N-well/P-substrate. In addition, the important factors influencing CMOS-APD performance are clarified from this investigation.
Performance Evaluation of Bidirectional Optical Amplifiers for Amplified Passive Optical Network Based on Broadband Light Source Seeded Optical Sources
Kang, Byoung-Wook ; Kim, Chul-Han ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 4~8
DOI : 10.3807/JOSK.2011.15.1.004
We have evaluated the performances of bidirectional optical amplifiers which were suited for the cost-effective implementation of amplified bidirectional passive optical networks (PONs). First, we measured the maximum gains of two simple bidirectional optical amplifiers implemented without using any optical components for the suppression of reflected signals. From the results, the maximum gains of two simple bidirectional amplifiers with a broadband light source (BLS) seeded optical source were limited to be 27 dB due to the reflection-induced in-band crosstalk, when the reflectance coefficients were measured to be -33 dB in both directions. Then, we have also implemented a bidirectional optical amplifier with two band splitters for the amplified bidirectional PON where the two different wavelength bands were allocated to the downstream and upstream signals transmission. In our measurement, we confirmed that the maximum gain of bidirectional optical amplifier with two band splitters could be increased to more than 30 dB owing to the efficient suppression of in-band crosstalk.
Measurement of the Internal Structure of an Optical Waveguide Embedded in a Flexible Optical Circuit Board by Enhancing the Signal Contrast of a Confocal Microscope
Lee, Won-Jun ; Kim, Dae-Chan ; O, Beom-Hoan ; Park, Se-Geun ; Lee, El-Hang ; Lee, Seung-Gol ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 9~14
DOI : 10.3807/JOSK.2011.15.1.009
In this study, the internal structure of an optical waveguide embedded in a flexible optical circuit board is observed with a confocal microscope. In order to increase the light reflection from an internal material interface with a very small index difference, and thus enhance the signal contrast, a theta microscopy scheme has been integrated into a conventional confocal microscope, and a high NA oil-immersion lens has been used. The interface reflectivity is increased from roughly 0.0015% to 0.025% by the proposed method, and the internal structure can thus be successfully measured.
Palmprint Verification Using Multi-scale Gradient Orientation Maps
Kim, Min-Ki ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 15~21
DOI : 10.3807/JOSK.2011.15.1.015
This paper proposes a new approach to palmprint verification based on the gradient, in which a palm image is considered to be a three-dimensional terrain. Principal lines and wrinkles make deep and shallow valleys on a palm landscape. Then the steepest slope direction in each local area is first computed using the Kirsch operator, after which an orientation map is created that represents the dominant slope direction of each pixel. In this study, three orientation maps were made with different scales to represent local and global gradient information. Next, feature matching based on pixel-unit comparison was performed. The experimental results showed that the proposed method is superior to several state-of-the-art methods. In addition, the verification could be greatly improved by fusing orientation maps with different scales.
Analysis of Specific Problems in Laser Scanning Optical System Design
Joo, Won-Don ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 22~29
DOI : 10.3807/JOSK.2011.15.1.022
We analyze aberrations in an optical laser printer system in order to know how to determine an allowable non-uniformity of the movement of a light spot, how to determine allowed variation of spot sizes, and how to minimize the influence of these deviations on technological errors. In this paper, the correction and the tolerance of distortion are analyzed by using the concept of zonal and global distortions. The tolerance of field curvature is also obtained from Gaussian beam properties. In order to reduce the change of the entrance pupil position and to make a more compact laser printer system the minimum size of the rotator is exactly derived from the geometry with the introduction of the shift angle of the input beam.
Precision Evaluation of Three-dimensional Feature Points Measurement by Binocular Vision
Xu, Guan ; Li, Xiaotao ; Su, Jian ; Pan, Hongda ; Tian, Guangdong ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 30~37
DOI : 10.3807/JOSK.2011.15.1.030
Binocular-pair images obtained from two cameras can be used to calculate the three-dimensional (3D) world coordinate of a feature point. However, to apply this method, measurement accuracy of binocular vision depends on some structure factors. This paper presents an experimental study of measurement distance, baseline distance, and baseline direction. Their effects on camera reconstruction accuracy are investigated. The testing set for the binocular model consists of a series of feature points in stereo-pair images and corresponding 3D world coordinates. This paper discusses a method to increase the baseline distance of two cameras for enhancing the accuracy of a binocular vision system. Moreover, there is an inflexion point of the value and distribution of measurement errors when the baseline distance is increased. The accuracy benefit from increasing the baseline distance is not obvious, since the baseline distance exceeds 1000 mm in this experiment. Furthermore, it is observed that the direction errors deduced from the set-up are lower when the main measurement direction is similar to the baseline direction.
Simple Model of Bright-room Contrast Ratio Measurement System for Plasma Display Panels with Contrast Enhancement Film
Beom, Tae-Won ; Park, Gi-Chan ; Park, Jong-Rak ; Kim, Young-Sik ; Zhang, Jun ; Song, Bu-Seup ; Chun, Jong-Pil ; Yoon, Ki-Cheol ; Jang, Won-Gun ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 38~43
DOI : 10.3807/JOSK.2011.15.1.038
We have developed a simple model of a bright-room contrast ratio (BRCR) measurement system for plasma display panels (PDPs) adopting a contrast enhancement film (CEF) by using an illumination design tool. Only four model parameters were used, namely, total ambient illumination power delivered by fluorescent lamps, a panel scattering rate, illuminance of PDP white patterns, and the absorption coefficient of a color adjusting film. These parameters were determined by simple optical measurements and matching simulations. The proposed model was employed to predict the BRCR values of four different CEF samples, and the simulated ones were found to be in agreement with measured ones within about 10% relative-error.
Development of an Illumination Measurement Device for Color Distribution Based on a CIE 1931 XYZ Sensor
Son, Do-Ky ; Cho, Eun-Byeol ; Moon, In-Kyu ; Park, You-Sang ; Lee, Chung-Ghiu ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 44~51
DOI : 10.3807/JOSK.2011.15.1.044
In this paper, an easy-to-use measurement device for illumination distribution is developed. The device consists of a sensor array module, a control module, and a PC interface. The sensor array module incorporates CIE 1931 color sensors and the ARM-based 96 MHz microcontroller in the control module for measurement and data processing. The sensor array module contains 64 color sensors arranged in a
array. The sensitivity of the sensor array module can be adjusted depending on the illumination level to be measured. The measurement data and control signals are exchanged via USB 2.0 standard. To demonstrate the performance of the device, the illumination distribution is measured for colors of red, green, and blue and is graphically shown. The device can be used for measurement of the illumination distribution, design and adjustment of LED illumination.
Stray Light Analysis of High Resolution Camera for a Low-Earth-Orbit Satellite
Park, Jun-Oh ; Jang, Won-Kweon ; Kim, Seong-Hui ; Jang, Hong-Sul ; Lee, Seung-Hoon ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 52~55
DOI : 10.3807/JOSK.2011.15.1.052
We discuss the effect of stray light on a high-precision camera in an LEO(Low Earth Orbit) satellite. The critical objects and illumination objects were sorted to discover the stray light sources in the optical system. Scatter modeling was applied to determine a noise effect on the surface of a detector, and the relative flux of a signal and noise were also calculated. The stable range of reflectivity of the beam splitter was estimated for various scattering models.
Solid-State Laser Mode-Locking Near 1.25 μm Employing a Carbon Nanotube Saturable Absorber Mirror
Cho, Won-Bae ; Choi, Sun-Young ; Kim, Jun-Wan ; Yeom, Dong-Il ; Kim, Ki-Hong ; Rotermund, Fabian ; Lim, Han-Jo ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 56~60
DOI : 10.3807/JOSK.2011.15.1.056
We demonstrate passive mode-locking of a Cr:forsterite laser with a single-walled carbon nanotube saturable absorber mirror (SWCNT-SAM). Without compensation of intra-cavity dispersion, the self-mode-locked laser generates 11.7 ps pulses at a repetition rate of 86 MHz. The dispersion-compensated laser yields ultrashort pulses as short as 80 fs near
at 78 MHz with average output powers up to 295 mW, representing the highest power ever reported for mode-locked solid-state lasers based on saturable absorption of SWCNTs in this spectral region.
Visualization of Epidermis and Dermal Cells in ex vivo Human Skin Using the Confocal and Two-photon Microscopy
Choi, Sang-Hoon ; Kim, Wi-Han ; Lee, Yong-Joong ; Lee, Ho ; Lee, Weon-Ju ; Yang, Jung-Dug ; Shim, Jong-Won ; Kim, Jin-Woong ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 61~67
DOI : 10.3807/JOSK.2011.15.1.061
The confocal laser scanning microscopy and two-photon microscopy was implemented based on a single laser source and an objective lens. We imaged and compared the morphology of identical sites of ex vivo human skin using both microscopes. The back-scattering emission from the sample provided the contrast for the confocal microscopy. The intrinsic autofluorescence and the second harmonic generation were used as the luminescence source for the two-photon microscopy. The wavelength of the Ti:Sapphire laser was tuned at 710 nm, which corresponds to the excitation peak of NADH and FAD in skin tissue. The various cell layers in the epidermis and the papillary dermis were clearly distinguished by both imaging modalities. The two-photon microscopy more clearly visualized the intercellular region and the nucleus of the cell compared to the confocal microscopy. The fibrous structures in the dermis were more clearly resolved by the confocal microscopy. Numerous cells in papillary dermal layer, as deep as
, were observed in both CLSM and two-photon microscopy. While most previous studies focused on fibrous structure imaging (collagen and elastin fiber) in the dermis, we demonstrated that the combined imaging with the CLSM and two-photon microscopy can be applied for the non-invasive study of the population, distribution and metabolism of papillary dermal cells in skin.
Age and Sex Related Changes in Corneal Thickness and Anterior Corneal Curvature in Korean Young Population with Orbscan II Topography System
Lee, Dong-Hee ; Kim, Douk-Hoon ; Park, Seung-Hwan ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 68~73
DOI : 10.3807/JOSK.2011.15.1.068
This study investigated, using the Orbscan II topography system, the influence of age and sex related changes on the corneal thickness and anterior corneal curvature, more specifically the fine structure of the cornea, in a Korean young population. The Orbscan II topography system is a computer-assisted slit-beam scanning technology that can map the anterior section of the cornea. The mean central corneal thickness of all subjects was
. There was no statistical difference (p>0.5) in the mean central corneal thickness between males and females. Sex and age related changes in the mean central corneal thickness had no specific statistical difference (P>0.5). There was a negative correlation between the anterior corneal curvature and the central corneal thickness in all subjects, except for the twenty year olds. However, the thickness relationship between the mean central corneal and the eight paracentral corneal thicknesses had strong statistical differences in all subjects. Also age and sex related changes in the central corneal thickness and the anterior corneal curvature in all subjects had no statistically significant difference, except from 20-26 years old (p>0.05). This information could be a suitable reference basis for future studies in the young population of Asia and for the development of examination tools for corneal refractive surgery.
Development of SD-OCT for Imaging the in vivo Human Tympanic Membrane
Cho, Nam-Hyun ; Jung, Un-Sang ; Kwon, Hyeong-Il ; Jeong, Hyo-Sang ; Kim, Jee-Hyun ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 74~77
DOI : 10.3807/JOSK.2011.15.1.074
We report a novel extension of 840 nm wavelength- based spectral domain optical tomography to in vivo/real-time human middle ear diagnosis. The system was designed to access the middle ear region with a specifically dedicated handheld probe. The real-time displaying feature was mandatory for in vivo imaging human subject with the handheld probe, and the system could provide about 20 frames per second for 2048 pixels by 1000 A-scans without using any graphics process units under the Labview platform. The inner ear structure of a healthy male volunteer was imaged with the developed system with the axial and lateral resolutions of
, respectively. The application of the OCT technology to early diagnose otitis media(OM) is very promising and could be another extensive branch in the OCT field because it provides the depth resolved image including tympanic membrane (TM) and structures below TM whereas the conventional otoscope technique only gives asurface image of the TM.
Solid Immersion Lens Microscope for Spectroscopy of Nanostructure Materials
Yim, Sang-Youp ; Kim, Joon-Heon ; Lee, Jong-Min ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 78~81
DOI : 10.3807/JOSK.2011.15.1.078
We demonstrate a high-spatial-resolution imaging and spectroscopy tool using a solid immersion lens (SIL), a hemispherical lens made of high refractive index glass (n ~2). Photoluminescence (PL) images of single CdSe nanocrystals confirm a numerical aperture enhancement factor of ~2, close to the refractive index of the SIL. In particular, a bare-eye observation of PL signals emitted by single nanocrystals with
densities was possible over an
diameter region. In addition, the PL spectra of single CdSe nanocrystals were successfully measured at room temperature. Thus, this SIL microscope ensures a simple but powerful method for nanostructure spectroscopy.
Numerical Investigation of Tunable Band-pass\band-stop Plasmonic Filters with Hollow-core Circular Ring Resonator
Setayesh, Amir ; Mirnaziry, Sayyed Reza ; Abrishamian, Mohammad Sadegh ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 82~89
DOI : 10.3807/JOSK.2011.15.1.082
In this paper, we numerically study both band-pass and band-stop plasmonic filters based on Metal-Insulator-Metal (MIM) waveguides and circular ring resonators. The band-pass filter consists of two MIM waveguides coupled to each other by a circular ring resonator. The band-stop filter is made up of an MIM waveguide coupled laterally to a circular ring resonator. The propagating modes of Surface Plasmon Polaritons (SPPs) are studied in these structures. By substituting a portion of the ring core with air, while the outer dimensions of the ring resonator are kept constant, we illustrate the possibility of red-shift in resonant wavelengths in order to tune the resonance modes of the proposed filters. This feature is useful for integrated circuits in which we have limitations on the outer dimensions of the filter structure and it is not possible to enlarge the dimension of the ring resonator to reach to longer resonant wavelengths. The results are obtained by a 2D finite-difference time-domain (FDTD) method. The introduced structures have potential applications in plasmonic integrated circuits and can be simply fabricated.
12-year LIDAR Observations of Tropospheric Aerosol over Hefei (31.9°N, 117.2°E), China
Wu, Decheng ; Zhou, Jun ; Liu, Dong ; Wang, Zhenzhu ; Zhong, Zhiqing ; Xie, Chenbo ; Qi, Fudi ; Fan, Aiyuan ; Wang, Yingjian ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 90~95
DOI : 10.3807/JOSK.2011.15.1.090
12-year LIDAR observations of tropospheric aerosol vertical distribution using a Mie scattering LIDAR in Hefei (
) from 1998 to 2009 are presented and analyzed in this paper. Characters of temporal variation and vertical distribution of tropospheric aerosol over Hefei are summarized from the LIDAR measurements. The impacts of natural source and human activities on the aerosol vertical distribution over Hefei could be seen clearly. Dust particles from the north in spring could affect the aerosol distributions below about 12 km over Hefei, and aerosol scale height in April reaches
. Both LIDAR measurements and surface visibility imply that aerosols in the lower troposphere have been increasing since about 2005.
Derivation of the Ambient Nitrogen Dioxide Mixing Ratio over a Traffic Road Site Based on Simultaneous Measurements Using a Ground-based UV Scanning Spectrograph
Lee, Han-Lim ; Noh, Young-Min ; Ryu, Jae-Yong ; Hwang, Jung-Bae ; Won, Yong-Gwan ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 96~102
DOI : 10.3807/JOSK.2011.15.1.096
Simultaneous measurements using a scanning spectrograph system and transmissometer were performed for the first time over an urban site in Gwangju, Korea, to derive the ambient
volume mixing ratio. The differential slant column densities retrieved from the scanning spectrograph system were converted to volume mixing ratios using the light traveling distance along the scanning line of sight derived from the transmissometer light extinction coefficients. To assess the performance of this system, we compared the derived
volume mixing ratios with those measured by an in situ chemiluminescence monitor under various atmospheric conditions. For a cloudless atmosphere, the linear correlation coefficient (R) between the two data sets (i.e., data derived from the scanning spectrograph and from the in situ monitor) was 0.81; the value for a cloudy atmosphere was 0.69. The two sets of
volume mixing ratios were also compared for various wind speeds. We also consider the measurement errors, as estimated from an error propagation analysis.
Wavelet Power Spectrum Estimation for High-resolution Terahertz Time-domain Spectroscopy
Kim, Young-Chan ; Jin, Kyung-Hwan ; Ye, Jong-Chul ; Ahn, Jae-Wook ; Yee, Dae-Su ;
Journal of the Optical Society of Korea, volume 15, issue 1, 2011, Pages 103~108
DOI : 10.3807/JOSK.2011.15.1.103
Recently reported asynchronous-optical-sampling terahertz (THz) time-domain spectroscopy enables high-resolution spectroscopy due to a long time-delay window. However, a long-lasting tail signal following the main pulse is often measured in a time-domain waveform, resulting in spectral fluctuation above a background noise level on a high-resolution THz amplitude spectrum. Here, we adopt the wavelet power spectrum estimation technique (WPSET) to effectively remove the spectral fluctuation without sacrificing spectral features. Effectiveness of the WPSET is verified by investigating a transmission spectrum of water vapor.