• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.275-281
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• 2010

This research's goal is to process directly aspherics with big sagment and thin center thickness. If we can process directly aspherics with big sagment and thin center thickness, we think it greatly helps to reduce the time of developing optical system. We made very thin glass using diamond grinding whetstone regarding the trace of tool and the detailed drawing of tool super precisive aspherics that has 0.46mm center thickness and over $30^{\circ}$ segment, $0.1{\mu}m$ machining accuracy, 15nm surface accuracy. We think this research's result will be effective to open new market because it is applied not only cell phone optical system but also CCTV robot optical system, internet phone optical system. Also we expect to enhance the super strong brittle precisive process's possibility with super precisive processing technique that achieves 0.46mm glass center thickness as first in the world.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.389-390
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• 2006

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.217-222
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• 1990

A general ray tracing scheme has been developed for using a personal computer which trace finite rays through any non-rotationally symmetric system. This scheme may be used for the surface type such as conic section with or without aspherics, toric surfaces, sagittal and tangential cylindrical sections and axicons. Specially, any combinational of decentered, tilted and rotated surfaces has been considered. Before transfering to the next surfaces, the local coordinates are refered back to an initial reference coordinate system. We can get a mathmtical model of a non-rotationally symmetrical finite ray trace running on an inexpensive personal computer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1566-1570
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• 2005

The aspherical lenses are used as optical lens of HMD optical system. The optimum cutting condition of PMMA lens sample with ultra precision SPDT, the diamond tool nose radius, the cutting speed, the feed rate, the depth of cut, and cutting fluid type are found. The demanded surface roughness 10 nm Ra, aspherical form error $1.0\;\mu{m}$ P-V for aspherical lens of optical data storage device are satisfied.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.3
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• pp.9-15
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• 2007

Three methods for grinding: cross grinding, slanted tool axis grinding and parallel grinding, were carried out to study the machinability of tungsten carbide mold for glass formed aspherics lens. In our research, the optimum grinding conditions were investigated in terms of feed-rate, relative velocity of wheel and work piece, tool marks and surface roughness. It is shown that cross grinding are most effective in removal ratio but poor in surface roughness. In addition, tool marks of each method were differentiated on direction and shape.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.427-427
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• 2007

The global applications of aspherics surfaces will expand rapidly on the electronics, optical components, communications, aerospace, defense, and medical optics devices etc. Especially, Asymmetric aspheric prism lens is one of the important parts in HMD(Head Mounted Display) because it affects dominantly on the optical performance of HMD. The mold core is the most important device to produce the plastic lenses by injection molding method. In this study, the mold cores for asymmetric aspheric prism lens were processed using fly-cutting method which is kind of the ultra precision processing and form accuracy and surface roughness of the cores were measured.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.159-162
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• 2010

There are some limitations to advance technology glaring and luminous Intensity uniformity known as the weak point of existing LED lamp. To improve the two weak points, there have been no special alternative methods so far. Instead, one method which is being used such as the twisting secondary lens or arbitrary structure to remove glaring and improve luminous Intensity uniformity. Based on this academic background, it is necessary to be examined on Technology of Optical System to solve the two weak points by using not complicated but simple methods. This paper will examine the angle of reflection in order to improve luminous intensity uniformity. Also, this research will present the method using lighting analysis program to verify a hypothesis. Through the analysis program, we could understand the simulation analysis method and got some problems about the analysis result. After analysis of causes through reinterpretation of problems, we have reached a conclusion that was changed according to reflectivity and the shape of aspherics by main cause which effected luminous Intensity uniformity and glaring.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.313-320
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• 2004

We present a null testing method fer aspheric surfaces, utilizing a phase-shifting diffraction grating interferometer along with a binary amplitude computer generated hologram (CGH). The binary amplitude CGH is designed to compensate for the wavefront between a point source and the aspheric surface under test. The fringe visibility of the grating interferometer is controlled easily by selecting suitable grating diffraction orders for the measurement and reference wavefronts or by optimizing the groove shape of the grating used. The binary amplitude CGH is designed by numerical analysis of ray tracing and fabricated using e-beam lithography for autostigmatic testing. Experimental results of a large-scale aspheric mirror surface are discussed to verify the measurement performance of the proposed diffraction grating interferometer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.191-194
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• 2003

Through using aspheric lens can result in advantages such as an improved optical transfer function, a reduced distortion path or the realization of special image field curvatures. Using the diamond turning method for generating aspherics, the company claim to be able to generate surfaces with a form error of less than $0.33\;{\mu}\;m$ and a surface roughness of less than $0.025\;{\mu}\;m$. In this paper, we are manufacturing thermal image aspheric lens. Thermal image system is electro-optical imaging device which can make visible the difference of infrared energy naturally emitted by objected. In the result of aspherical surface, the form accuracy of about $0.24\;{\mu}\;m$ P-V was obtained and the surface roughness Ra $0.004\;{\mu}\;m$. Also, a brief review of Ultra-precision system Korea photonics technology institute(KOPTI) is present in this paper.

• Korean Journal of Optics and Photonics
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• v.28 no.6
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• pp.290-294
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• 2017

The Cassegrain telescope consists of a primary concave mirror and a secondary convex mirror. In the case of a secondary mirror, it is more difficult to test wavefront error than for a primary mirror, because it reflects the entire testing beam, as it is convex in shape. In this paper we tested the wavefront error of a complex aspheric convex secondary mirror by using the Simpson-Oland-Meckel Hindle test. To separate the systematic errors, such as fabrication error and alignment error of a meniscus lens, we adopted the QN absolute test (pixel-based absolute test using the quasi-Newton method) as well. Finally, we compared the measured result with that of an ASI (Aspheric Stitching Interferometer) made by the QED company, which resulted in an rms difference of only 2.5 nm, showing a similar shape of astigmatism aberration.