• 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.

• Korean Journal of Optics and Photonics
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• v.18 no.1
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• pp.14-18
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• 2007

Photonic crystal fibers(PCFs) with silica cores within an away of air holes have unique properties. Broad band single-mode and the octave-spanning supercontinuum generation, impossible to achieve in classical fibers, can be realized. The design of PCFs is very flexible. There are two parameters to manipulate: air hole diameter, and lattice pitch. We introduced a fabrication process for control of the parameters to obtain endlessly single mode PCF, which is single mode in a large wavelength range, and highly nonlinear PCF. The numerical analysis and experiments are included.

• Korean Journal of Optics and Photonics
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• v.29 no.1
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• pp.13-18
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• 2018

In this study, we present a symmetry graphical method to design an achromatic optical system composed of many lenses on an achromatic glass map. To take into account the lens spacing and the number of lenses, we use the relative ratio of paraxial ray height at each lens and the concept of an equivalent single lens. Converting an arbitrary optical system into various doublet systems, the most effective doublet is then selected to correct the color aberration, through material selection and the redistribution of the optical power. By designing a fisheye lens using this approach, an achromatic optical system is effectively obtained over the visible waveband.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.7-11
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• 2000

The anti-reflective anti-static (ARAS) optical film is designed using absorbent materials such as ITO, $TiN_xW_y$, Ag by Essential Macleod program. [air ${\mid}TiN_xW_y{\mid}SiO_2{\mid}$ glass] two layer shows wide-band AR coating in the wavelength range of 450~700 nm. The reflectivity, transmittance of this coating are below 0.5%, about 75%, respectively. [air $SiO_2{\mid}TiO_2{\mid}SiO_2{\mid}$, ITO glass] layer can adjust reflectance of below 0.5% with above 97% transmittance. In the [air ${\mid}SiO_2{\mid}TiO_2{\mid}SiO_2{\mid}$ Ag glass] layer, the transmission can be controlled at above 96% with reflectance of 1~2%.

• Korean Journal of Optics and Photonics
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• v.21 no.6
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• pp.235-240
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• 2010

We fabricate highly birefringent photonic crystal fiber with new structure using a stack and draw method. Fabricated fiber has two big air holes, one at each side of the outside air cladding region, leading to core ellipticity during the drawing process. Birefringence of the fabricated Hi-Bi PCF is measured to be $2.29{\times}10^{-4}$ (at 1550 nm).

• Korean Journal of Optics and Photonics
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• v.29 no.4
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• pp.139-148
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• 2018

In this study, aerosol size distributions were retrieved from aerosol optical depth measured over a range of 10 wavelengths from 250 to 1100 nm. The 10 wavelengths were selected where there is no absorption of atmospheric gases. To obtain the solar spectrum, a home-made solar tracking system was developed and calibrated. Using this solar tracking system, total optical depths (TODs) were extracted for the 10 wavelengths using the Langley plot method, and aerosol optical depths (AODs) were obtained after removing the effects of gas absorption and Rayleigh scattering from the TODs. The algorithm for retrieving aerosol size distributions was suggested by assuming a bimodal aerosol size distribution. Aerosol size distributions were retrieved and compared under various arbitrary atmospheric conditions. Finally, we found that our solar tracking spectrometer is useful for retrieving the aerosol size distribution, even though we have little information about the aerosol's refractive index.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.34-42
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• 2005

This paper presents the optimum initial design containing the first and third order properties of the three-group zoom system using lens modules, and the real lens design of the system. The optimum initial design with focal length range of 4.3 mm to 8.6 mm is derived by assigning appropriate first and third order quantities to each module along with the specific constraints required for the system. An initial real lens selected for each group has been designed to match its focal length and the first orders into those of the each lens modules, and then combined to establish an actual zoom system by adjusting the air space between the groups at all zoom positions. The combination of the separately designed groups results in a system which satisfies the first order properties of the zoom system composed of the original lens modules. As a result, by residual aberration correction, we could obtain a zoom system useful in compact digital zoom cameras and mobile phone cameras employing the rear focus method.

• Korean Journal of Optics and Photonics
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• v.20 no.1
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• pp.57-60
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• 2009

We consider introducing an optical thin film to the light guiding wall of a pixel in order to enhance the light guiding efficiency of a CMOS image sensor. Simulating the reflectance as a function of the incidence angle using the Essential Macleod program, we find that the range of total internal reflection is greatly increased for several materials. Particularly when air is chosen as the thin film material, the critical angle of total internal reflection could be shifted to about 50 degrees.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.8-13
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• 2010

Satellite structure should be designed to accommodate and support safely the payload and equipments necessary for its own missions and to secure satellite and payloads from severe launch environments. The launch environments imposed on satellites are quasi-static accelerations, aerodynamic loads, acoustic loads and shock loads. Especially when optical payload is accommodated, satellite structure usually adopts the optical bench consisting of composite material not only to support and secure but also to guarantee good pointing stability against extreme thermal environments. This paper deals with optical bench and support structure which shall be designed to minimize the loads transferred to optical payloads from satellite.

• Journal of the Korea Computer Graphics Society
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• v.9 no.1
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• pp.1-2
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• 2003

본 논문에서는 액체와 기체가 상호작용 하는 현상들에 대한 새로운 유체 애니메이션 기법을 액체 속 공기방울의 예를 사용하여 제시한다. 기존의 자유표면 시뮬레이션 기법들과는 달리 액체와 기체를 함께 시뮬레이션 할 경우에는 기체의 유동과 액체의 유동을 동시에 다루어야 하며 비중 차에 의한 부력과 경계면에서의 표면장력 등을 추가적으로 고려해야 한다. 유체의 토폴로지 변화를 쉽게 다루면서도 수치적 분산을 막기 위하여 유체 역학 분야의 VOF (Volume of Fluid) 기법과 프론트 추적 (Front-tracking) 기법을 혼합하여 사용하였다. 액체와 기체의 경계면은 마칭 큐브즈 알고리즘을 사용하여 폴리곤으로 복원된 후 버텍스 쉐이더 기술들을 사용하여 액체-기체 경계면의 광학적인 특성을 표현할 수 있었다.