• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.116-121
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• 1997

The optical power drift due to temperature variation of a laser diode driven by constant voltage is different from one driven by constant current. When a laser diode is driven by constant current, the optical output decreases as the temperature increases because the population inversion decreases. However, When it is driven by constant voltage, injection current increases with temperature rise, which in turn increases the optical power. As the result, the optical power variation reduces. Experimental results show that when these two components are almost equal and cancel each other, the optical power variation coefficient is very small and the optical output is stable.

• Journal of the Optical Society of Korea
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• v.19 no.2
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• pp.182-187
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• 2015

This paper presents a new graphical method for selecting a pair of optical glasses to simultaneously achromatize and athermalize an imaging lens made of materials in contact. An athermal glass map that plots thermal glass constant versus inverse Abbe number is derived through analysis of optical glasses and plastic materials in visible light. By introducing the equivalent Abbe number and equivalent thermal glass constant, although it is a multi-lens system, we have a simple way to visually identify possible optical materials. Applying this method to design a phone camera lens equipped with quarter inch image sensor having 8-mega pixels, the thermal defocuses over $-20^{\circ}C$ to $+60^{\circ}C$ are reduced to be much less than the depth of focus of the system.

• Proceedings of the Optical Society of Korea Conference
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• 1997.08a
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• pp.13-13
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• 1997

• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.1-6
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• 2016

The performance of a set of low-cost optical components used for measuring the optical density of PM particles was evaluated in the present study. To this end, the set of low-cost optical components was replaced with that of general optical components used to measure the PM optical density under identical experimental conditions. The optical densities measured from the set of general optical components were then compared to those obtained from the set of low-cost optical components. While the optical density is measured, another key parameter, the dimensionless extinction constant of PM particles (which is needed to optically measure the PM concentration) was also determined in the present study. The experimental results indicate that the optical density and PM concentration measurements performed by low-cost optical components are feasible, producing trackable variations in the OD and concentrations compared to values obtained from the set of general optical components.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.153-154
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• 2009

In this study, a new accommodation-dependent crystalline lens with a constant volume and homogeneous refractive index is developed. The human lens parameters, such as curvature and thickness, are calculated at the central parts of the lens, and the asphericity is adjusted at the peripheral parts of the lens due to accommodation. We propose a accommodating schematic eye which is suitable for easy paraxial calculations because the refractive index of the lens remains uniform and constant.

• KSBB Journal
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• v.32 no.1
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• pp.35-45
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• 2017

In this work the optical fiber glucose and lactate biosensors were developed by using fluorescent dye and enzyme immobilized on the end tip of an optical fiber. 3-Glycidyloxypropyl)methyldiethoxysilane (GPTMS), (3-Aminopropyl) trimethoxysilane (APTMS) and Methyltrimethoxysilane (MTMS) were used to immobilize glucose oxidase (GOD), lactate oxidase (LOD) and ruthenium(II) complex (tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II), $Ru(dpp)_3^{2+}$) as oxygen sensitive fluorescent dye. MTMS sol-gel was an excellent supporting material for the immobilization of $Ru(dpp)_3^{2+}$, GOD, and LOD on the optical fiber. Storage stability of the optical fiber glucose sensor was kept constant over 20 days, while the optical fiber lactate sensor had constant storage stability over 17 days. The optical fiber glucose and lactate biosensors also maintained good operational stability for 20 hours and 14 hours, respectively. The activities of the immobilized enzymes were most excellent at pH 7 and at $25^{\circ}C$. On-line monitoring of glucose and lactate in a simulated process was performed with the optical fiber glucose and lactate biosensors. On-line monitoring results were agreed with those of off-line data measured with high performance liquid chromatography (HPLC).

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.256-263
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• 2007

High NA objective design by using SELFOC materials was studied, and two kinds of objective for optical pick-up were designed. The SELFOC materials have radial gradient index distribution, and it gives additional degree of freedom in optical design. Therefore, we expect that optical design of high NA objective without aspheric surface will be possible. In this study, the variation of ms spot diameter was investigated as a function of quadratic constant and refractive index on axis for various combinations of axial thickness and entrance pupil diameter. For the survey, Code V was used for optimization and evaluation of the objective lenses. The result suggested that larger quadratic constant and higher refractive index on axis could give us better imaging performance for all combinations of axial thickness and pupil diameter. Based on the survey, we designed high NA objectives for DVR. There were two kinds of design solution consisting two spherical SELFOC lenses. The solution I had positive-positive lens configuration with short over-all-length, but it had poor off-axial performance compared with the solution II. The solution II had negative-positive lens configuration with good off-axial imaging performance. But the solution II had some disadvantages, long over-all-length and large diameter of the second lens.

• Journal of the Optical Society of Korea
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• v.9 no.2
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• pp.45-48
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• 2005

We investigate effects of the injected ASE (Amplified spontaneous emission) bandwidth on the performance of the wavelength-locked Fabry-Perot laser diodes (F-P LDs) under constant injection power density and constant injection power. For the constant injection power density, we can determine the minimum injection bandwidth by the required intensity noise or the bit-error rate (BER) performance. On the other hand, there exists the optimal ASE bandwidth for the constant injection power to minimize the intensity noise.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.444-450
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• 2010

The traditional approach to inverting aerosol extinction makes use of the assumption of a constant LIDAR ratio in the entire Mie-LIDAR signal profile using the Fernald method. For the large uncertainty in the cloud optical depth caused by the assumed constant LIDAR ratio, an not negligible error of the retrieved aerosol extinction below the cloud will be caused in the backward integration of the Fernald method. A new algorithm to determine aerosol extinction below a cirrus cloud from Mie-LIDAR signals, based on a new cloud boundary detection method and a Mie-LIDAR signal modification method, combined with the backward integration of the Fernald method is developed. The result shows that the cloud boundary detection method is reliable, and the aerosol extinction below the cirrus cloud found by inverting from the modified signal is more efficacious than the one from the measured signal including the cloud-layer. The error due to modification is less than 10% taken in our present example.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.183-186
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• 1991

In order to prepare the functional organic optic meterials, the capacitive coupled gas flow type plasma polymerization apparatus was designed and manufactured. Styrene and para-Xylene monomer were adopt as organic materisl. Optical constant, refrative index, extinction coefficient of organic thin films by the gas flow type plasma polymerization appratus were determined by envelope method using spectrophotometry. The refractive index of plasma polymerized thin films was decreased in accordance to increase of wave length and discharge time. The extinction coefficient was very small compared with refractive index. From the experimental result of optical constant and film thickness, it was considered that the films which had required optical properties and thickness can be prepared by control of polymerization condition.