• Bulletin of the Korean Space Science Society
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• 2009.04a
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• pp.39.3-39.3
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• 2009

• The Bulletin of The Korean Astronomical Society
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• v.34 no.1
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• pp.75.1-75.1
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• 2009

• Journal of the Optical Society of Korea
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• v.13 no.2
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• pp.201-205
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• 2009

We investigated the optimum adhesive thickness for athermalizing an elastomeric lens mount in our space optics application. Theoretical results were compared with finite element solutions using two different models; discrete circular pads and discrete circular pads with columns filling the insertion holes reflecting the reality. A noticeable difference between their optimal thicknesses was observed, and physical interpretation revealed the uncertainty of prevailing athermal equations. A pilot sample was made to check our results and thermo-optical stress was assessed using an interferometer after isothermal load. This study presented insight into preliminary design guidance in elastomeric lens mounting.

• Korean Journal of Optics and Photonics
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• v.31 no.5
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• pp.231-231
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• 2020

• The Bulletin of The Korean Astronomical Society
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• v.31 no.1
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• pp.20.2-20.2
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• 2006

• Journal of the Optical Society of Korea
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• v.15 no.4
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• pp.394-397
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• 2011

For the purpose of fabricating off-axis aspheric optics, we propose an 8-axis-polishing machine combined with a testing tower whose height is up to 9 m. The proposed polishing machine was designed and analyzed by using a well-known finite element method. The eight axes of the machine have a synchronized motion generated by a computer, and each axis was calibrated by a heterodyne laser interferometer or an optical encoder. After calibration, the maximum positioning error of the machine was less than 2 ${\mu}m$ within a whole 2 m ${\times}$ 2 m area. A typical fabrication result of a ${\phi}1.5$ m concave mirror was also described in this manuscript.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.34.2-34.2
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• 2010

We built 7 potential extra-terrestrial planets including the full 3D Earth model with various surface types and 6 planet models, each with uniform surface characteristics. The surface types include ice, tundra, forest, grass, ground and ocean. We then imported these 7 planets into integrated ray tracing(IRT) model to compute their disk averaged spectra and to understand the spectral behavior depending on the geometrical view, illumination phase and seasonal change. The IRT computation show that the 6 planets with uniform surfaces exhibit clear spectral differences from that of the Earth. We then built a phase and seasonal DAS database for the 6 uniform surface planets and used them for parametric spectral decomposition technique to derive the Earth DAS. This computation resulted in the first potential solution to the surface type ratio of the Earth compared to the measured earth surface type ratio. The computational details and the implications are discussed.

• Journal of electromagnetic engineering and science
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• v.17 no.3
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• pp.165-167
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• 2017

We predict the electromagnetic wave propagation in space environments using geometrical optics. The effective indices of the troposphere, stratosphere, and ionosphere are computed, and the reflection, refraction, and attenuation of electromagnetic waves in space environments are calculated based on the ray tracing technique and geometrical optics. The influence of the refractive index and loss of atmosphere and the incident angle of the antenna on electromagnetic wave propagation is discussed.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.3
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• pp.199-205
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• 2014

We propose a new variant of lateral shearing interferometer with a tunable laser source that enables 3D surface profile measurements of freeform optics with high speed, high vertical resolution, large departure, and large field-of-view. We have verified the proposed technique by comparing our measurement result with that of an existing technique and measuring a representative sample of freeform optics. Moreover, we propose a new algorithm that is able to compensate the rotational inaccuracy.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.26.1-26.1
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• 2010

In this report, we present newly improved optical design for the Amon-Ra energy channel and its optical performance. The design is optimized parametrically with emphasis on improved light concentration. And then its performances are computed, first, from a laboratory test simulation using laser method (wave optics approach) and, second, from an in-orbit radiative transfer simulation using IRT method with 3D Earth model (geometrical optics approach). Two simulation test results show clear evidence of energy concentration improvement.