• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.1-4
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• 2013

For the conventionally polished fused silica substrate, an around 100 nm depth redeposition polishing layer was formed on the top of surface. Polishing compounds, densely embedded in the redeposition polishing layer were the dominant factor that limited the laser induced damage threshold (LIDT) of transmission elements in nanosecond laser systems. Chemical etching, super-precise polishing and ion beam etching were employed in different ways to eliminate these absorbers from the substrate. After that, Antireflection (AR) coatings were deposited on these substrates in the same batch and then tested by 1064 nm nano-pulse laser. It was found that among these techniques only the ion beam etching method, which can effectively remove the polishing compound and did not induce extra absorbers during the disposal process, can successfully improve the LIDT of AR coatings.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.2
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• pp.39-43
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• 2008

Atmospheric pressure plasma polishing (APPP) is a noncontact precision machining technology that uses low temperature plasma chemical reactions to perform atom-scale material removal. APPP is a complicated process, which is affected by many factors. Through a preliminary theoretical analysis and simulation, we confirmed that some of the key factors are the radio frequency (RF) power, the working distance, and the gas ratio. We studied the influence of the RF power and gas ratio on the removal rate using atomic emission spectroscopy, and determined the removal profiles in actual operation using a commercial form talysurf. The experimental results agreed closely with the theoretical simulations and confirmed the effect of the working distance. Finally, we determined the element compositions of the machined surfaces under different gas ratios using X-ray photoelectron spectroscopy to study the influence of the gas ratio in more detail. We achieved a surface roughness of Ra 0.6 nm on silicon wafers with a peak removal rate of approximately 32 $mm^{3}$/min.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.63-68
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• 2018

At present, ultra-precision cutting technology has been studied in Korean research institutes, focusing on development of ultra-precision cutting tool technology and ultra-precision control engineering. However, the developed technologies are still far behind advanced countries. It focuses on metals including aluminum, copper and nickel, and nonmetals including plastics, silicone and germanium which require high precision while using a lathe. It is hard to implement high precision by grinding the aforementioned materials. To address the issue, the ultra-precision cutting technology has been developing by using ultra-precision machine tools very accurate and strong, and diamond tools highly abrasion-resistant. To address this issue, this study aims to conduct ultra-precision cutting by using ECTS (Error Compensation Tool Servo) to improve motion precision of elements and components, and compensate for motion errors in real time. An IR camera is used for analyzing cutting accuracy differences depending on the heat generated in diamond tools in cutting to examine the heat generated in cutting to study cutting accuracy depending on generated heat.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.51-54
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• 2008

A novel stereolithography method using evanescent light has been proposed as a means to realize 100-nanometer resolution. An in-process measurement system with high accuracy has been introduced to the nanostereolithography apparatus. Specifically, an optical microscopic system was developed to monitor the exposure process and a confocal positioning system was established to improve the longitudinal positioning accuracy in the layer-by-layer process. A high-power objective lens, a tube lens, and a charge coupled device (CCD) were included in the optical microscopic system, whereas a laser, a high-power objective lens, a piezoelectric (PZT) stage, a condenser lens, a pinhole, and a photomultiplier (PMT) made up the confocal microscopic system. Two verification experiments were conducted, and the results indicated that the optical microscopic system had a horizontal resolution of 200 nm and that the confocal positioning system provided a depth resolution of 30.8 nm. These results indicate that nanostereolithography can be successfully performed with this system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.75-76
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.103-104
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.671-672
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.455-458
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• 2002

In recent years, precision positioning stage is demanded fur some industrial fields such as semi conductor lithography, ultra precision machining and fabricating of nano structure. In this research, precision multi-axis positioning stage, which consists of pzt actuator, flexure, and capacitance gauge, is designed and developed. The performance of it such as 3-axis positioning, characteristic of motion and resolution is verified.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.259-260
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• 2006

• 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