• Korean Journal of Optics and Photonics
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• v.22 no.1
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• pp.16-22
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• 2011

We fabricate a measuring system to measure the modulation transfer function (MTF) of a mid-infrared imaging silicon lens by using the knife-edge scanning technique. In particular, we measure on-axial tangential MTF of the silicon lens with the focal length of 50 mm and F-number F/4 in the wavelength band of mid-infrared between $3\;{\mu}m$ and $5\;{\mu}m$. In order to obtain the infinite object, the off-axial parabolic reflector with the focal length of 2.545 m is utilized. In the comparison with measured MTF data and designed MTF values curve, we find that the tolerance of measured MTF data below the spatial frequency of 7 lp/mm is within 2%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.4
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• pp.318-325
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• 2015

Pico satellite has limited surface to install the solar cells due to its extremely limited size. Also, the sun incidence angle with respect to the solar panel continuously varies according to the attitude control strategy and its important parameter for the power generation. In this study, a concentrating photovoltaic system for pico satellite application has been proposed that can enhance the power generation efficiency in case of the unfavorable condition of the sun incidence angle with respect to the solar panel of the satellite using the fresnel lens. To prove the possibility of maximizing the power generation efficiency of the proposed concentrating power system, we have performed the power measurement test using a solar simulator and commercial fresnel lens. And on-orbit analysis of the power generation efficiency using the STK which is a commercial S/W has also been performed based on the test results.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.44.1-44.1
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• 2017

The single lens event OGLE-2015-BLG-1482 has been simultaneously observed from two ground-based surveys and from Spitzer. The Spitzer data exhibit finite-source effects due to the passage of the lens close to or directly over the surface of the source star as seen from Spitzer. Thanks to measurements of the microns parallax and the finite-source effect, we find that the lens of OGLE-2015-BLG-1482 is a very low-mass star with the mass $0.10{\pm}0.02M{\odot}$ or a brown dwarf with the mass $55{\pm}9MJ$, which are respectively located at $DLS=0.80{\pm}0.19kpc$ and $DLS=0.54{\pm}0.08kpc$, and thus it is the first isolated low-mass microlens that has been located in the Galactic bulge. The degeneracy between the two solutions is severe. The fundamental reason for the degeneracy is that the finite-source effect is seen only in a single data point from Spitzer and this single data point gives rise to two ${\rho}$ solutions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.13-19
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• 2012

Ultra Precision Machining Techniques, such as manufacturing Micro Lens Array(MLA), off-axis mirror, $F-{\theta}$ lens for laser printer, are achieved, based on technologies in consequence of development of modern high-precision machining mechanism. Above all, FTS(Fast Tool Servo) and STS(Slow Tool Servo) are more innovative technologies for reducing time and development costs. In this paper, it is described that MLA machining technique by FTS, off-axis mirror machining technique by STS, optics for observing space, and development of infrared aspheric lens for a thermal imaging microscope.

• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.460-462
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• 2001

We have analyzed the characteristics of IR lens mounting with elastomer and applied the results to the mounting of a silicon lens with diameter 117 mm which is the objective of a thermal imaging system. The elastomer, the 577 primerless silicone adhesive (Dow Corning Co.) which is heat cure type, and the mount material, A16061 are used for our analysis. Theoretical analysis gives the result that the space between lens and mount is required to be more than 250 ${\mu}{\textrm}{m}$ under the operational temperature conditions of -40~+6$0^{\circ}C$.

• 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.

• Communications of the Korean Mathematical Society
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• v.4 no.2
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• pp.321-329
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• 1989

• The Bulletin of The Korean Astronomical Society
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• v.34 no.2
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• pp.50.1-50.1
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• 2009

• The Bulletin of The Korean Astronomical Society
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• v.22
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• pp.33.2-34
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• 1997

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.81-87
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• 1997

This paper presents the optimum initial design containing the first and third order properties of the four-group video camera zoom system using lens modules, and its real lens design. The optimum initial design with focal length range of 6.1693 to 58.4065 mm is derived by assigning appropriate first order quantities and third order aberrations to each module along with the specific constraints required for optimization. By scaling the focal length of each lens group, an initial real lens selected for each group has been designed to match its focal length into that of the each lens module, 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 consisting of original lens modules. As a result, by residual aberration correction, we could obtain a zoom system useful in video zoom camera employing the rear focus method.