• Korean Journal of Optics and Photonics
• /
• v.10 no.5
• /
• pp.357-363
• /
• 1999

A frequency domain spectroscopic system was constructed to investigate the optical properties of multiple scattering media. The alternating current (AC) and phase lag components of backscattered light were measured by using the heterodyne detection method. Absorption and transport scattering coefficients were computed from the values based on diffusion theory. Predictions showed excellent matches in comparison with actual values of absorption and scattering. Predictable ranges of the optical coefficients were analyzed in terms of the distance between light source and detector, and modulation frequencies. A proposed compact experimental set-up using laser diodes can be utilized to estimate non-invasively the optical properties of multiple scattering media such as biological tissues.

• Proceedings of the Optical Society of Korea Conference
• /
• 2009.02a
• /
• pp.285-285
• /
• 2009

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.1
• /
• pp.92-97
• /
• 2008

This is a research to apply 1310nm single-mode optical fiber to a temperature sensor. The existing study of optical fiber sensor is complicated because it was made with various equipment. To vary scattering, the variation of optical frequency is measured by using Bragg(lattice) or pulse generator and also bulk system is created by YAG laser but there were some difficulties creating experimental environment and it was a problem that the stability of measured data was low. The temperature sensor system using the suggested sBs(stimulated Brillouin scattering:sBs) from this research is much more simplified straight-line system. To improve the trust and accuracy of noises from optical frequency and unclear results, it was analysed by using Neuro-Fuzzy algorithm. we tried to get more correct data than existing system. sBs measure that optical frequency changed due to the variation of temperature. The analyzed change rate of outcome by Fuzzy theory is 1.1 MHz.

• Korean Journal of Optics and Photonics
• /
• v.6 no.4
• /
• pp.324-330
• /
• 1995

Stimulated Brillouin scattering theory is described in an optical fiber. Frequency change with an optical heterodyne method is analyzed between reference signal of a source and stimulated Brillouin scattering signal in an optical fiber. By coupling a source with a few axial modes and an optical fiber ring resonator, Brillouin scattering is studied with a spectrum analyzer. Using reference beating signal of a source, we have reduced the Brillouin beating frequency from 13 GHz range to below GHz. Experimentally, we can see the Brillouin beating frequency from 13 GHz range to below GHz with a dispersion shifted fiber (1.32 GHz), Ti-doped fiber (900 MHz) and single mode optical fiber (870 MHz). MHz).

• Korean Journal of Optics and Photonics
• /
• v.8 no.4
• /
• pp.345-352
• /
• 1997

Recently, in designing optical mask such as 4GDRAM, the scattering effect of electromagnetic wave must be considered. For this reason we claculated directly the mask function using the finite difference time domain(FDTD) method. The modification of image theory with this new mask function could explain clearly the scattering effect at the etched side wall of the submicron optical mask. The characteristics of the various type of alternating PSM were investigated. According to the simulation, the dual wet etch process was the most useful fabrication technique to overcoe the light scattering off at the shifted opening.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.1
• /
• pp.135-140
• /
• 2003

The convergence of finite volume method (FVM) or discrete ordinate method (DOM) is known to degrade for optical thickness greater than unity and large scattering albedo. The present article presents a convergence acceleration procedure for the FVM based on a full approximation storage (FAS) multigrid method. Among a variety of multigrid cycles, the V-cycle is used and the full multigrid algorithm (FMG) is applied to an analysis of radiation in irregular two-dimensional geometry. Solution convergence is discussed for the several cases of various optical thickness and scattering albedo. At small scattering albedo and optical thickness, there is no advantage to using the multigrid method for calculation CPU time. For large scattering albedo greater than 0.5 and optical thickness greater than unity, however, the multigrid method improves the convergence and the solution is rapidly obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.8
• /
• pp.611-617
• /
• 2001

The non-polar optical phonon scattering in the valence band depends on the masses, ratios, and types of mixtures of constituent atoms. Therefore, the random distribution of atoms in alloy semiconductors should be considered in the analysis of scattering mechanisms. For this purpose, the force equations of n atoms in a unit cell are expressed in a n x n matrix form to obtain the angular frequencies due to the acoustic and non-polar optical phonons. And, n is then assumed to be infinity. When this work is compared with other results published elsewhere, it is concluded that the independence of atomic displacement or amplitude of oscillation as ell as the infinite number of atoms in a unit cell must be taken into account for the random distribution of atoms in alloy semiconductors.

• Journal of Information Display
• /
• v.13 no.4
• /
• pp.139-143
• /
• 2012

In this study, optical simulation was used to compare three optical structures that could be applied to the typical organic light-emitting diode to increase the outcoupling efficiency. These were spherical scattering particles (treated as Mie scatterers) embedded in the glass substrate, microlenses formed on the glass substrate, and a diffusing layer (DL) with a Gaussian scattering distribution function inserted between the indium tin oxide (ITO) and the glass substrate. It was found that the application of microlens array and that of scattering particles in the glass substrate exhibited similar enhancements in the outcoupling efficiency when the density and the refractive index of the scattering particles were optimized. The DL located at the interface between the glass and the ITO further enhanced the efficiency because it could further extract the trapped light in the waveguide mode. The appropriate combination of these three structures increased the outcoupling efficiency to about 42%, which is much greater than the typical values of 15-20% when there is no optical structure for light extraction.

• Current Optics and Photonics
• /
• v.3 no.6
• /
• pp.597-604
• /
• 2019

This study was performed to evaluate objective visual quality and ocular scattering in myopic refractive-surgery patients, compared to emmetropes. Optical vision-quality parameters (modulation transfer function (MTF) cutoff and Strehl ratio) and objective scattering index (OSI) were measured using an optical quality analysis system (OQAS II) based on the double-pass technique. In all subjects, the higher the MTF cutoff and Strehl ratio, the lower the OSI and ocular higher-order aberrations (HOAs). The MTF cutoff and Strehl ratio for the laser-assisted subepithelial keratectomy (LASEK) group were lower than those for the emmetropia group, while the OSI, ocular HOAs, and spherical aberration (SA) for the LASEK group were higher than those for emmetropia group. Ocular scattering would be one of the important factors in regard to visual quality. Therefore, the quality of the retinal image in the LASEK patients has been shown to reduce the quality of vision more than in the emmetropes.

• Proceedings of the Optical Society of Korea Conference
• /
• 2005.07a
• /
• pp.186-187
• /
• 2005