• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.57.3-58
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• 2016

We analyze an optical system of a telescope based on Fresnel type objective lens as suggested by Hyde (1999). The Fresnel objective lens can be thin, light-weight and foldable, and therefore it is possible to develop a space telescope with an aperture larger than that of traditional telescopes. Moreover a lens, whatever it is either Fresnel type or conventional, allows much larger fabrication tolerances. We design a medium-sized telescope adopting Fresnel lens as an objective lens for use in space and possibly on the ground. The well-known chromatic aberration of the Fresnel primary lens is corrected by a field lens and another Fresnel lens using Schupmann method. An additional lens is used for forming images. We analyze the chromatic and off-axis aberrations of the proposed system analytically and suggest methods for the minimization of off-axis aberrations and for the operation in wider spectral range. We also conduct ray tracing and optimize the whole optical system with commercial software. Finally we present the design parameters of a telescope with an aperture of 0.5 to 1 meters, enabling diffraction limited operation for a moderate field of view about 10 arc-minutes.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.6_spc
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• pp.687-696
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• 2016

A series of process to design an acoustic lens for underwater imaging is reviewed and the method to evaluate characteristics of the lens is investigated. If the target specification of lens is given, the design process consists of the material selection, evaluation of its properties, lens geometry design, prediction of lens characteristics, manufacturing, and evaluation by measurement. In this study, an actual acoustical lens is made by cutting polymethylpentene block. The characteristics of lens are predicted by the hybrid method, combination of ray tracing and Rayleigh integral. For the direct comparison between the prediction and measurement results, a simulation method based on the equivalent source method is suggested to reflect the actual radiation pattern of transducer used for measurements. Finally, the measurement is conducted in a small water tank to observe the actual characteristics of the manufactured lens.

• Korean Journal of Optics and Photonics
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• v.34 no.6
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• pp.276-282
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• 2023

In this paper, we designed a lighting optical system using a freeform lens as a substitute for expensive gobo lighting. Unlike gobo lighting, freeform lens lighting does not use an image mask, and it can form and project an image directly on the lens surface using only a single lens, thus reducing the cost compared to gobo lighting. In order to verify the performance of freeform lens lighting with these advantages, we conducted an illuminance simulation. As a result, it was confirmed that it can replace gobo lighting because it has an illuminance distribution similar to the image we want to irradiate and a light efficiency of 47% similar to the performance of gobo lighting.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1113-1116
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• 2001

Recently, the needs of non-symmetric spherical lens are increasing. Machining non-symmetric spherical lens by general method is limited. This paper researches grinding machine method for non-symmetric spherical lens and accruable problems at processing lens using CAD/CAM. In addition, this paper researches the relation of curvatures to grinding wheel sizes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.2019-2023
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• 2005

A aspheric lens is one a key point optical element in the optical industry. The feature of a aspheric lens is not to have the spherical aberration. A aspheric lens is also essential element for high-precision and light-weight in the optical machine. Generally it have been used in a tailor progression an aspheric lens modelling much. In this study we applied a lay back-tracer using a index of refraction to draw a creative aspheric lens. And we executed a comparison experiment for refraction situation of shape and straightness experiment to inspect the drawn aspheric lens in this study

• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.43-48
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• 2008

This paper proposes a new method for measuring the power of spherical and cylindrical lens with 6 points light source, which is composed of a LED and six holes, and magnification ellipse fitting algorithm. Each measured diagonal length of 6 points light source is determined by the target lens power. After finding the center position of each light point with threshold method, 3 axis-diagonal lengths were calculated. The long axis and short axis power of cylindrical lens can be calculated by using magnification ellipse fitting algorithm with the magnification relationships between the initial diagonal lengths and the measured diagonal lengths changed by lens power.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.6
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• pp.1-7
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• 2012

Recently an optical diffusion of LED lamps has been studied actively. In this paper, the second lens applied to a cover of the LED lamp was analytically designed to having a wide angle distribution of light without diffuser characteristic by dispersing agent. In this process, We found a major factors that can help improve the performance of the lens. It is the refractive power of the lens, the Mie particle density of phosphor, and the arrangement of the LED. Through the final simulation, we can see the LED lamp is possible to get wide angle light distribution by proper source modeling and second lens designing. Also, we can see this simulated results are entirely consistent with measured data for light distribution. In this research, we present the shape of the second lens with wide angle distribution and derive the important factors for the second lens design.

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.305-313
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• 1996

Lens design method by using equivalent lenses was already introduced, but the method has a limitaion that all lenses should be in the air. Therefore, we often get improper solution in designing cemented lenses. In this study, the lens conversion from thick lens to equivalent lens and its reversal was generalized without any preconditions, and the third order aberration fomulrae were derived for the generalized equivalent lens system. The generalized equivalent lens conversion were applied to typical cemented doublet and triplet, and they show that the third order aberrations of the generalized equivalent lenses have better agreements with their corresponding thick lenses than the previous conversion method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.3
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• pp.3-8
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• 2007

This study is for aspheric lens that is one of a core technology in the optical industry. The feature of a aspheric lens is not to have the spheric aberration. So in optical industry, aspheric lens are essential element to miniaturization, high effectiveness and light weight. In this study we applied a lay back-tracer method using the index of refraction to design aspheric lens. We developed the automatic design program for aspheric lens by user interfacing program VisualLISP in AutoCAD. And we manufactured aspheric lens and measured it.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.964-967
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• 2001

Aspherical lens with the higher numerical aperture has been needed in the optical storage device to increase the recording density on the disk. However, high numerical aperture means the large slope angle at the clear aperture of the lens. Therefore, the measurement and manufacturing technique including the lens molding process for the slope angle should be developed. In this paper, the evaluation technique was described for the optical performance of the aspherical lens. Aspherical form error brings about the wavefront error and the side lobe of the beam intensity profile. A schematic diagram of the aspherical lens manufacturing was drawn to explain the aspherical form error compensation. Finally, form error of the aspherical lens was defined and plotted using the raw data of the Formtalysurf.