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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Korean Journal of Optics and Photonics
Journal Basic Information
Journal DOI :
Optical Society of Korea
Editor in Chief :
Volume & Issues
Volume 20, Issue 6 - Dec 2009
Volume 20, Issue 5 - Oct 2009
Volume 20, Issue 4 - Aug 2009
Volume 20, Issue 3 - Jun 2009
Volume 20, Issue 2 - Apr 2009
Volume 20, Issue 1 - Feb 2009
Selecting the target year
A Terahertz Yagi-Uda Antenna with High Input Impedance
Han, Kyung-Ho ; Nguyen, Troung Khang ; Park, Ik-Mo ; Han, Hae-Wook ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 65~70
DOI : 10.3807/HKH.2009.20.2.065
In this paper, a THz Yagi-Uda antenna with high input impedance is designed. By placing the antenna on a thin substrate, end-fire radiation patterns with high antenna impedance can be obtained even when the substrate has high relative dielectric constant. The proposed Yagi-Uda antenna has high input resistance of approximately
at the resonance frequency which is obtained by using a U-shaped dipole as a driver element. It is expected that the Yagi-Uda antenna on a thin substrate can achieve much higher terahertz output power than the conventional THz antennas.
Field Probe Sensor Based on the Electro-Optic Effect
Kyoung, Un-Hwan ; Kim, Gun-Duk ; Eo, Yun-Seong ; Lee, Sang-Shin ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 71~75
DOI : 10.3807/HKH.2009.20.2.071
A compact electric field probe sensor incorporating two different electro-optic materials of
and GaAs was proposed and fabricated, and it was used to measure the strength of the horizontal and vertical fields generated by a microstrip ring-resonator filter. The sensitivities of the sensors in
and GaAs were
respectively, and their signal to noise ratios were approximately
respectively. And the operating frequency range was up to
. The electric field profile for the test circuit was scanned and found to be in good agreement with that obtained by using the HFSS simulation.
Analysis of Characteristics of Finger-Print Recognition According to Computer Generated Hologram and Its Reconstructed Image
Jeong, Man-Ho ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 76~80
DOI : 10.3807/HKH.2009.20.2.076
Finger-print recognition is achieved by comparing an input finger-print image with the stored images in the computer, and finally by determining agreement or disagreement. Encryption and decryption are necessary in the finger-print recognition process. In these process CGH (Computer Generated Hologram) is used, and finger-print images reconstructed from the CGHs are compared. In this paper, two methods of recognition are used, one is to compare the finger-print images of each other reconstructed from their CGHs and the other is to compare the CGHs to each other directly, to analyze the differences of finger-print recognition capability between these two methods. Experimental results show that the capability of finger-print recognition for comparing the CGHs of the two is about 150 times higher than in case of comparing the reconstructed finger-print images. Especially the changes of characteristics according to modulation types of CGH are analyzed.
Height Measurement by Refractive Index Difference and Digital Holography
Cho, Hyung-Jun ; Kim, Doo-Cheol ; Yu, Young-Hun ; Shin, Sang-Hoon ; Lee, Hyuk-Soo ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 81~86
DOI : 10.3807/HKH.2009.20.2.081
Digital holography and refractive index difference are used to measure a high aspect ratio's patterns. When interference fringes are very closely spaced, the phase data containing high frequencies where
ambiguities cannot be resolved. In this technique, the optical path difference is decreased by decreasing the refractive index difference. As a result, we solve the
ambiguities. Also, this technique is applicable to measure the refractive index if the shape of the sample is known.
Simulation of Distortion in Image Space due to Observer's Rotation Movement in Stereoscopic Display, and Its Correction
Kim, Dong-Wook ; Lee, Kwang-Hoon ; Kim, Sung-Kyu ; Chang, Eun-Young ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 87~93
DOI : 10.3807/HKH.2009.20.2.087
Variation of the observer's viewing position is one of the major causes of image space distortion in the stereoscopic display. Especially, a large image distortion, which is caused by different depth direction positions of the observer's two eyes, is made by the observer's rotation movement in relation to the center of the screen. This is different from distortion of horizontal and depth directional movement of the observer. In this paper, we analyzed distortion of the image space due to the observer's rotation movement and showed the corrected result of distortion through simulation in the stereoscopic display. Finally, we showed that the distortion shape of the observer's rotation movement is different from horizontal and depth directional movement of the observer.
Object-Based Integral Imaging Depth Extraction Using Segmentation
Kang, Jin-Mo ; Jung, Jae-Hyun ; Lee, Byoung-Ho ; Park, Jae-Hyeung ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 94~101
DOI : 10.3807/HKH.2009.20.2.094
A novel method for the reconstruction of 3D shape and texture from elemental images has been proposed. Using this method, we can estimate a full 3D polygonal model of objects with seamless triangulation. But in the triangulation process, all the objects are stitched. This generates phantom surfaces that bridge depth discontinuities between different objects. To solve this problem we need to connect points only within a single object. We adopt a segmentation process to this end. The entire process of the proposed method is as follows. First, the central pixel of each elemental image is computed to extract spatial position of objects by correspondence analysis. Second, the object points of central pixels from neighboring elemental images are projected onto a specific elemental image. Then, the center sub-image is segmented and each object is labeled. We used the normalized cut algorithm for segmentation of the center sub-image. To enhance the speed of segmentation we applied the watershed algorithm before the normalized cut. Using the segmentation results, the subdivision process is applied to pixels only within the same objects. The refined grid is filtered with median and Gaussian filters to improve reconstruction quality. Finally, each vertex is connected and an object-based triangular mesh is formed. We conducted experiments using real objects and verified our proposed method.
Eye-Tracking 3D Display System Using Variable Parallax Barrier and DDC/CI
Che, Ho-Byoung ; Yoo, Young-Rok ; Kim, Jin-Soo ; Lee, Sang-Hun ; Lee, Seung-Hyun ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 102~109
DOI : 10.3807/HKH.2009.20.2.102
In this paper, we introduce an eye-tracking 3D display system using variable parallax barrier and DDC communication. A barrier of variable parallax barrier composed of 4 sub-barriers and a commercially available web camera is utilized to implement the eye-tracking system. The coordinates of a viewer is extracted from the web camera transfer to 3D display via DDD/CI communication. The variable barrier attached to the LCD moves electrically according to the right eye position for 3D images. This system is compared experimentally with the commercial parallax barrier methods.
Uncertainty Evaluation of Color Measurement on Light Sources and Display Devices
Park, Seong-Chong ; Lee, Dong-Hoon ; Kim, Yong-Wan ; Park, Seung-Nam ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 110~117
DOI : 10.3807/HKH.2009.20.2.110
This work introduces the uncertainty evaluation formulation on color measurement of light sources and display devices, such as CIE 1931 (x, y) chromaticity, CIE 1960 (u, v) chromaticity, correlated color temperature, and distribution temperature. All the mentioned quantities are reduced from spectral data in the visible range, for which uncertainties are strongly correlated between different wavelengths. Using matrix algebra we have formulated the uncertainty propagation from the SI- traceable spectral irradiance standard to the individual color related measurement quantities taking the correlation between wavelengths into account. As a result, we have demonstrated uncertainty evaluation examples of 3 types of light sources: CIE illuminant A, LED white light, and LCD white light. This method can be applied to any other quantities based on spectral measurement such as solar irradiance, material color measurement, etc.
Fabrication of Microlens Array Using Photoresist Thermal Reflow
Hwang, Sung-Ki ; Baek, Sang-Hoon ; Kwon, Jin-Hyuk ; Park, Yi-Soon ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 118~122
DOI : 10.3807/HKH.2009.20.2.118
An optical sheet with microlens array (MLA) is designed and fabricated as a substitute for the prism sheets of LCD backlight. Using photoresist thermal reflow, MLAs were fabricated on PET film with thickness of
, and we measured the change of MLA profile in terms of exposure time, reflow temperature and reflow time.
Study of Diffraction Efficiency Values for Photopolymer Films Added TiO
Her, Ki-Young ; Kim, Dae-Heum ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 123~127
DOI : 10.3807/HKH.2009.20.2.123
In order to improve the diffraction efficiency of the photopolymer, we prepared a
added photopolymer and investigated the optical properties. Prepared photopolymer films are based on polyvinyl alcohol (PVA) as a polymer binder, acryl amide (AA) as a photo-polymerizable monomer, triethanolamine (TEOA) as an initiator, and eosin Y as a sensitizer at 532 nm. To prepare the photopolymer films with the uniform thickness, the constant amount (2.5 ml) of the photopolymer solution was dropped on the glass and spread using a spin coater. Then films were dried for 72 hrs in a darkroom (
, 40% RH) prior to the optical measurement. Then, the diffraction efficiencies of both the photopolymer films containing
and non-contained films were measured with the various incident angles (
added photopolymer showed 5% higher diffraction efficiency than neat photopolymer without
addition. The addition of
into the photopolymer showed the high diffraction efficiency (over 70%) at broad range (
) of the incident angle.
Design of Internal Coupling Structure for Touch Panel Devices Using Optical Coupling of a Pen-Shaped Light Source with Optical Waveguides
Park, Dae-Seo ; Kim, Dae-Jong ; O, Beom-Hoan ; Park, Se-Geun ; Lee, El-Hang ; Lee, Seung-Gol ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 128~133
DOI : 10.3807/HKH.2009.20.2.128
In this paper, an optical touch panel device is newly proposed, with operating principle based on the optical coupling between a pointing pen having a built-in light source and perpendicularly crossed optical waveguide arrays. In order to enable an external light to couple into a waveguide core, the auxiliary pyramidal structures are introduced into all intersecting points located periodically along optical waveguides. The shape is optimized for minimizing the unwanted propagation loss due to the same structure by a ray tracing method. For the optical waveguide with the size of
, the bottom width, height, and slope angle of the optimized pyramidal structure are
, respectively. The optical coupling efficiency of about 97.8% and the average propagation loss of 0.3 dB/mm were achieved for the optimized touch panel. Finally, it is found from the tolerance analysis that tilting of the pen up to
can be allowed.
Measurement and Analysis of Light Scattering of Au Pads on PCB Surface to Extract Scattering Parameters
Ko, Nak-Hoon ; Park, Dae-Seo ; Kim, Young-Seok ; O, Beom-Hoan ; Park, Se-Geun ; Lee, El-Hang ; Lee, Seung-Gol ; Choi, Tae-Il ;
Korean Journal of Optics and Photonics, volume 20, issue 2, 2009, Pages 134~140
DOI : 10.3807/HKH.2009.20.2.134
In this study, the influence of surface roughness on light scattering from Au pads on a PCB surface was investigated. Angular distributions of light scattered from Au pads with different surface roughness were measured for several incident angles. Diffusely-scattered light could be separated by using the fact that the amount of specularly-scattered light was directly related to surface roughness. The separated diffuse term was curve-fitted with a physics-based model, and then the related scattering parameters were extracted and compared with measured parameters.