• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.175-180
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• 2007

In this paper, an aberration free aspherical lens is designed and machined by new design method and the spherical aberration measuring system is developed. It confirmed the propriety of new design method by measuring optical characteristics of machined lens with the new measuring system. The system could measure a spherical aberration quantitatively by using CCD camera, laser, collimator and so on.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.52-55
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• 2002

In this research, the modification method of spherical aberration, and aspherical lens shape design method were investigated. Spherical aberration affects lens's performance directly. Many studies have attempted to remove spherical aberration with a lot of methods in order to reduce the bad effect of spherical aberration. The approach to lens shape design was base on the ray tracing method. From the result, it was confirmed that ray reverse-tracing method was convenient to remove spherical aberration, and could be used very effectively and usefully for aberration-free aspherical lens design.

• Journal of the Korean Statistical Society
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• v.25 no.2
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• pp.277-288
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• 1996

The minimum aberration criterion is commonly used for selecting good fractional factorial designs. In this paper we give same necessary conditions for $3^{n-k}$ fractional factorial designs. We obtain minimum aberration $3^{n-k}$ designs for k = 2 and any n. For k > 2, minimum aberration designs have not found yet. As an alternative, we select a design with minimum aberration among minimum-variance designs.

• Journal of the Optical Society of Korea
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• v.12 no.3
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• pp.186-191
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• 2008

A phase retrieval method using an error reduction algorithm is developed for reconstructing a wavefront aberration of an 100-TW Ti:sapphire laser pulse from the measurement of a focal spot. The phase retrieval method can successfully reconstruct a wavefront aberration of a 100-TW Ti:sapphire laser pulse, and the reconstructed wavefront aberration shows a good agreement with the wavefront aberration measured with a wavefront sensor. The effect of the dynamic range and the intensity noise on the reconstruction is also investigated in reconstructing a wavefront aberration of an 100-TW Ti:sapphire laser pulse.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.128-129
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• 1999

Polygon Mirror Scanning(PMS) is composed of LED array, magnifying lens, polygon mirror and motor. It is important to correct the lens aberrations to gain the image we want to show. In this paper, we have simulated the lens aberration correction to reduce the spherical aberration . We have obtained a aspherical lens which is corrected the spherical aberration.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.315-320
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• 2013

We have investigated the variation of spherical aberration of the anterior and posterior surface in a Korean sample population with various age between 20 to 71 years old. We used Pentacam (Oculus Inc., Germany) to measure the corneal radius, asphericity, and spherical aberration of 290 patients with normal cornea. There were negative correlation between corneal anterior radius and spherical aberration(r = -0.22, p<0.0001), and, there were negative correlation between corneal posterior radius and spherical aberration(r=-0.27, p < 0.0001). There were positive correlation between anterior asphericity and spherical aberration(r = 0.24, p < 0.0001), however there were negative correlation between posterior asphericity and spherical aberration(r = -0.17, p=0.00288).The average of anterior spherical aberration and posterior spherical aberration was $0.482{\pm}0.099{\mu}m$ and $-0.098{\pm}0.029{\mu}m$. The average of spherical aberration was $0.385{\pm}0.097{\mu}m$. There were significant positive correlations between anterior spherical aberration and age(r = 0.227, p<0.0001), and there were positive correlations between posterior aberration and age(r = 0.349, p<0.0001). It is considered that this data can be used as basic information for furture studies for improving the quality of vision of modern human and, through the analysis of the spherical aberration of cornea was to provide a better understanding of the optical part of the Korean's eye.

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.336-342
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• 2012

A low-cost optimal double-prism method is proposed by using the developed MATLAB program to correct chromatic aberration. We present an efficient approach to choose a couple of low-cost glasses to obtain a low aberration double prism. The doublet prisms were made of two lead-free glasses. The relative partial dispersion of the two lead-free glasses is identical and their Abbe numbers are different greatly. The proposed design aims to minimize chromatic aberration, such as in apochromats, for paraxial ray tracing. Finally, an optimization design for real ray tracing can be evaluated by the chromatic aberration curve with a minimal area.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.199-206
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• 2014

Purpose: The present study was aimed to investigate the correlation between higher-order aberration and myopic degree by the analysis of fluctuation of high-order aberration according to the change of myopic degree in certain ranges of myopia and astigmatism. Methods: The high-order aberration in a total of 992 eyes was analyzed by using a LADARWave device employing Hartmann-Shack system, and the relation between high-order aberration and myopia by the change of myopic degree through manifest refraction test. Results: In all subjects, spherical aberration and total coma aberration were significantly increased by the increase of myopic degree, however, trefoil aberration and astigmatic aberration and tetrafoil aberration were decreased. With the group of lower myopic degree, the change of coma aberration was greater by myopic degree and its change was significantly different. The change of spherical aberration by myopic degree was greatly large in the a group of -3.00 D or more and the group of -6.00 D or more where as its change was not large in the group of lower than -3.00 D. The significant decrease of coma aberration was observed only in the group of astigmatic degree of -1.00 D or less when analyzing the correlation between the higher-order aberrations and myopia in the certain groups of astigmatic degree. In the case of spherical aberration, the significant change was shown in all astigmatic groups, however, its increase was larger with the increase of myopic degree in lower degree of astigmatism. The consistent relationship in variations of horizontal and vertical coma aberration in certain myopic and astigmatic groups was neither established nor statistically significant. Conclusions: It is concluded that the correlation between the higher-order aberration and low-order aberration obtained from the results of the present study can help the understanding related to vision quality and the improvement of vision quality.

• Korean Journal of Optics and Photonics
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• v.30 no.1
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• pp.8-14
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• 2019

This paper presents methods to correct and evaluate the chromatic aberration occurring on the cut-off line of a headlamp without additional optical components and alignment process. To correct the chromatic aberration using a geometrical concept, the maximum differences in exit-ray angle between wavelengths are reduced by tilting the convex surface of an aspheric projection lens. To evaluate the chromatic aberration, the position and luminous intensity to be measured are suggested, and the criterion for chromatic aberration is presented through color coordinates. From the evaluation of an automotive headlamp designed using this geometrical method, it is found that the chromatic aberration of the cut-off line is significantly reduced.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.70-75
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• 2004

In this study, the pattern of lens aberration was studied at different injection molding conditions such as injection speed, holding pressure, holding pressure time, mold temperature and cylinder temperature and, then, the results were analyzed with a laser interferometer. It was demonstrated that optimal condition of lens aberration could be achieved by adjustment of injection molding conditions.