• The Bulletin of The Korean Astronomical Society
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• v.28 no.2
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• pp.51-51
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• 2003

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.26-26
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• 2003

During fabrication process for the large space optical surfaces, the traditional bound abrasive grinding with bronze bond cupped diamond wheel tools leaves the machine marks and the subsurface damage to be removed by subsequent loose abrasive lapping. We explored a new grinding technique for efficient quantitative control of precision CNC grinding for space optics materials such as Zerodur. The facility used is a NANOFORM-600 diamond turning machine with a custom grinding module and a range of resin bond diamond tools. The machining parameters such as grit number, tool rotation speed, work-piece rotation speed, depth of cut and feed rate were altered while grinding the work-piece surfaces of 20-100 mm in diameter. The input grinding variables and the resulting surface quality data were used to build grinding prediction models using empirical and multi-variable regression analysis methods. The effectiveness of the grinding prediction model was then examined by running a series of precision CNC grinding operation with a set of controlled input variables and predicted output surface quality indicators. The experiment details, the results and implications are presented.

• Publications of The Korean Astronomical Society
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• v.22 no.3
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• pp.55-61
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• 2007

The KASINICS (Korea Astronomy and Space science Institute Near Infrared Camera System) is a ground-based near-infrared (NIR) imaging instrument. KASINICS has offner relay optics to reduce unwanted infrared light. For the offner optics, we adopted an ultra precision machining process which is installed at KBSI (Korea Basics Science research Institute). Since the offner relay optics is made of aluminum 6061 metal material, we did several tests to reach the specification. We found that a 0.497mm radius nose bite and 220m/min machining speed are best tool and condition to make this offner optics with the precision machine. In this paper, we report the technical method of ultra precision machining and results of the KASINICS offner optics.

• 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.

• The Bulletin of The Korean Astronomical Society
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• v.28 no.1
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• pp.43-43
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.607-608
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• 2010

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.66-66
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• 2004

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.25-32
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• 2007

• Journal of Space Technology and Applications
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• v.4 no.3
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• pp.185-198
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• 2024

Korea Astronomy and Space science Institute (KASI) partnered with the Australian National University (ANU) to develop the adaptive optics (AO) system at the Geochang observatory with a 100 cm optical telescope for multiple applications, including space geodesy, space situational awareness and Korean space missions. The AO system is designed to get high resolution images of space objects with lower magnitude than 10 by using themselves as a natural guide star, and achieve a Strehl ratio larger than 20% in the environment of good seeing with a fried parameter of 12-15 cm. It will provide the imaging of space objects up to 1,000 km as well as its information including size, shape and orientation to improve its orbit prediction precision for collision avoidance between active satellites and space debris. In this paper, we address not only the design of AO system, but also analyze the images of stellar objects. It is also demonstrated that the AO System is achievable to a near diffraction limited full width at half maximum (FWHM) by analyzing stellar images.

• Journal of the Optical Society of Korea
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• v.10 no.1
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• pp.48-54
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• 2006

White-light scanning interferometry (WLI) and phase shifting interferometry (PSI) are increasingly used for surface topography measurements, particularly for areal measurements. In this paper, we compare surface profiling results obtained from above two optical methods with those obtained from stylus instruments. For moderately rough surfaces ($Ra{\approx}500\;nm$), roughness measurements obtained with WLI and the stylus method seem to provide close agreement on the same roughness samples. For surface roughness measurements in the 50 nm to 300 nm range of Ra, discrepancies between WLI and the stylus method are observed. In some cases the discrepancy is as large as 109% of the value obtained with the stylus method. By contrast, the PSI results are in good agreement with those of the stylus technique.