• Journal of the Optical Society of Korea
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• v.20 no.3
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• pp.427-430
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• 2016

The effect of the liquid density difference on interface shape of a double-liquid lens is analyzed in detail. The expressions of interface shape of two liquids with liquid density difference are analyzed and fitted with “even asphere”. The imaging analysis of the aspheric interface shape of a double-liquid lens is presented. The results show that the density difference of two liquids can cause the interface to be an aspheric surface, which can improve the image quality of a double-liquid lens. The result provides a new selection for the related further research and a wider application field for liquid lenses.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.290-296
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• 2019

Head-up displays for vehicles play an important role in displaying various information about the safety and convenience of driving on the windshield of the vehicle. In this study, ultra-precision machining was performed and evaluated as a method for machining a large-area aspheric free-form mirror that is applicable to augmented reality technology. Precision diamond cutting is highly accurate and suitable for the production of advanced parts with excellent surface integrity, low surface roughness, and low residual stress. By using an aspheric free-form mold, it is possible to improve the optical transfer function, reduce the distortion path, and realize a special image field curvature. To make such a mold, the diamond cutting method was used, and the result was evaluated using an aspherical shape-measuring machine. As a result, it was possible to the mold with shape accuracy (PV) below $1{\mu}m$ and surface roughness (Ra) below $0.02{\mu}m$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.9
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• pp.808-811
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• 2007

Aspheric glass lens have recently been used in camera phone module because they are more effective than spherical ones. In this paper, the grinding condition of the tungsten carbide molding core has been found after applying DOE to the development of the aspheric glass lens for the 3 Megapixel and 2.5x camera-phone module. Also, the ultra precision grinding process was investigated under this condition by experiment. Re-Ir coating was applied on the ground surface of the tungsten carbide molding core. The influence of Re-Ir coating on the form accuracy and surface roughness of molding core was compared and evaluated. The form accuracy and surface roughness of the molding core were improved by application of Re-Ir coating on the surface of the tungsten carbide molding core.

• Journal of Astronomy and Space Sciences
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• v.31 no.4
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• pp.341-346
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• 2014

A prototype of the GMT FSM has been developed to acquire and to enhance the key technology - mirror fabrication and tip-tilt actuation. The ellipsoidal off-axis mirror has been designed, analyzed, and fabricated from light-weighting to grinding, polishing, and figuring of the mirror surface. The mirror was tested by using an interferometer together with CGHs, which revealed the surface error of 13.7 nm rms in the diameter of 1030 mm. The SCOTS test was employed to independently validate the test results. It measured the surface error to be 17.4 nm rms in the diameter of 1010 mm. Both tests show the optical surface of the FSMP mirror within the required value of 20 nm rms surface error.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.57-62
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• 2009

Recently, with the increasing lightness and miniaturization of high resolution camera phones, the demand for aspheric glass lens has increased because plastic and spherical lens are unable to satisfy the required performance. An aspheric glass lens is fabricated by the high temperature and pressure molding using a tungsten carbide molding core, so precision grinding technology for the molding core surface are required. This paper reports a development of feedrate control grinding method for aspherical molding core using parallel grinding method. A plane molding core was ground using conventional and feedrate control grinding method. The performance of the feedrate control method was evaluated by measurement of surface roughness. The result indicated that the average surface roughness was reduced to 1.5 nm, which is more efficient than the conventional grinding method.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.1
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• pp.93-100
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• 2001

We analyzed aspheric patterns after we investigated zoom lens' constructions and optical capacities of a ordinary designed 35mm camera with an aspheric zoom lens system in this research. As this lens system was the zoom lens system about infinite object point, it was made to get a short back focal length, be able to use a lens unit more close to the image plane, and be used the compact camera which got a viewing system. The zoom ratio of the system was 1 : 2 and it got a positive and negative power's distribution. As it was determined the 35~70 mm focal length range which the most common people used, it might be called economic optical system considered universality. As it was used two aspheric surface, it was used just three lens, compensated the aberration and schemed lens' miniaturization, lightweightization, and the decrease effect of the unit cost of production.

• Korean Journal of Optics and Photonics
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• v.24 no.3
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• pp.111-119
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• 2013

A large aspheric mirror is a key component for large astronomical telescopes and high resolution satellite cameras. Since it is large and has an aspheric form, it is much more difficult to fabricate it compared to the similar size of spherical mirror. Especially, the opto-mechanical design and analysis is critical to reduce the deformation of mirror surface due to the external forces such as gravity or temperature change, as the mirror size is larger and lightweighting ratio is increased. The design requirements for the mirror are different depending on the particular ground and space applications because the environmental conditions are changed. In this paper, we explain the opto-mechanical design and analysis for ground and space applications that are among the most difficult to achieve among several technologies related to development of the large aspheric mirror.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.3
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• pp.124-131
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• 2007

Aspheric glass lenses was fabricated by glass molding press(GMP), which is a plano-aspheric convox shape and intended for use as an optical design of 3 megapixel and 2.5 magnifications zoom in a camera phone module. Transcription ratio of form accuracy (PV) as well as resolution properties was measured for evaluation the molded lens. Form accuracy (PV) of the mold surface was $0.127\;{\mu}m$ in an aspheric and $0.168\;{\mu}m$ in a plano, in case of the molded lens it shows $0.205\;{\mu}m$ and $0.223\;{\mu}m$, respectively. Resolution of the molded lens was measured as a MTF[Contrast]. The molded lens shows contrast of 32.9% at 80 1p/mm and the value is similar with contrast of 33% obtained simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.448-451
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• 2005

An aspheric mirror, which requires less than $\lambda/2\;(\lambda=632.8nm)$ of form error for the $\phi$ 200mm reference curved surface, has been manufactured with an ultra-precision turning machine. We have known through several tests that the deformation patterns of the reflecting surface is related with bolting positions. In this paper the effect of main factors on deformation of a reflector is studied with a FE code. The considered factors are angular velocity, natural frequencies for a mirror, temperature increment during machining. The obtained test results are similar to the deformation shape due to the assumed temperature increment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.11
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• pp.1050-1054
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• 2006

There have been intensive and continuous efforts in the field of DLC coating process because of their feature, like high hardness, high elasticity, abrasion resistance and chemical stability and have been applied widely the industrial areas. In this research, optimal grinding condition was investigated using Microlens Process Machine for the development of aspheric glass lens which is to be used for mobile phone module with 3 mega pixel and 2.5X optical zoom, and tungsten carbide(WC) mold cote was manufactured using high performance ultra precision machining and the effects of DLC coating on the form accuracy(PV) and surface roughness(Ra) of WC mold core was evaluated.