• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.414-417
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• 2005

Single point diamond turning technique for optical crystals is studied in this paper. The main factors which are influential the machined surface quality are discovered and regularities of machining process are drawn. Optical crystals have found more and more important applications in the field of modern optics. Optical crystals are mostly brittle materials of poor machinability. The traditional machining method is polishing which has many shortcomings such as low production efficiency, poor ability to be automatically controlled and edge effect of the workpiece. The purpose of our research is to find the optimal machining conditions for ductile cutting of optical crystals and to apply the SPDT technique to the manufacturing of ultra precision optical components of brittle material(Ge). Many technical challenges are being tried for the large space infrared telescope, which is one of the major objectives of the National Strategic Technology Road Map (NSTRM).

• 한국공작기계학회논문집
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• 제10권5호
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• pp.31-38
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• 2001

This paper deals with the micro turning property of setting angle using diamond tool. The bed of the system has used the granite which has the thermal and vibrational characteristics superior to the cast iron bed for the common machine tool. To minimize the inner and outer vibration of the fuming system, an air pad system was manufactured and tested. The aero-static spindle system which has the excellent rotation accuracy was designed and manufactured. As a result of the micro-cutting test on aluminum alloy, tool setting angel have effected on surface roughness. From the results, the micro-cutting conditions hope to provide the useful actual data using in industrial fields.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.939-942
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• 2000

Single point diamond turning technique for optical crystals is reported in this paper. The main factors influencing the machined surface quality are discovered and regularities of machining process are drawn. Optical crystals have found more and more important applications in the field of modern optics. Optical crystals are mostly brittle materials of poor machinability. The traditional machining method is polishing which has many shortcomings such as low production efficiency, poor ability to be automatically controlled and edge effect of the workpiece. The purpose of our research is to find the optimum machining conditions for ductile cutting of optical crystals and apply the SPDT technique to the manufacturing of ultra precision optical components of brittle material.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.184-187
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• 2005

This paper is described about the technique of ultra-precision machining for optical parts in HMD system. Machining technique for PMMA and BK7 with single point diamond turning machining is reported in this paper. The main factors influencing on the machined surface quality are discovered and regularities of machining process are drawn. The purpose of our research is to find the optimum machining conditions fur cutting of PMMA and grinding of BK7. Also, apply the SPDTM technique to the manufacturing of ultra precision optical components of HMD system. Aspheric PMMA lens without a polishing process, the surface roughness of 5 nm Ra, and the form error of ${\lambda}/2\;({\lambda}=632.8nm)$ for reference curved surface 30 mm has been required.

• 한국산학기술학회논문지
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• 제20권1호
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• pp.290-296
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• 2019

차량용 HUD는 자동차 전면 유리창에 안전 운전과 편의 운전 관련 다양한 정보를 표시해 주는 장치로 중요한 역할을 수행한다. 본 논문에서는 증강현실 기술에 적용이 가능한 대면적 비구면 자유형상 미러를 가공하기 위해 초정밀 가공기를 이용하여 가공을 실시하였고 그 결과를 측정하였다. 초정밀 다이아몬드 절삭은 정밀도가 높을 뿐만 아니라 표면 거칠기와 잔류 응력을 낮게 할 수 있어서 우수한 표면 무결성을 갖는 고급 부품의 생산에 유리하다. 또한 비구면 자유 형상의 몰드를 사용함으로써 광학 전달 함수의 개선, 왜곡 경로의 감소 및 특수 이미지 필드 곡률의 실현과 같은 장점을 얻을 수 있다. 이와 같은 비구면 자유형상 금형을 가공하기 위한 방법으로는 초정밀가공기를 이용한 다이아몬드 절삭 방법을 사용하였으며, 제작된 비구면 자유형상 미러 금형의 평가는 비구면 형상 측정기를 이용하여 실시하였다. 이러한 방법에 의해 $1{\mu}m$ 이하의 형상 정밀도(PV)와 $0.02{\mu}m$ 이하의 표면 거칠기(Ra)를 갖는 비구면 자유형상 금형을 제작할 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.83-87
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• 2001

A 110 mm diameter aspheric metal secondary mirror for a test model of an earth observation satellite camera was fabricated by ultra-precision single point diamond turning (SPDT). Aluminum alloy for mirror substrates is known to be easily machinable, but not polishable due to its ductility. A harder material, Ni, is usually electrolessly coated on an Al substrate to increase the surface hardness for optical polishing. Aspheric metal secondary mirror without a conventional polishing process, the surface roughness of Ra=10nm, and the form error of $Ra={\lambda}/12({\lambda}=632nm)$ has been required. The purpose of this research is to find the optimum machining conditions for reflector cutting of electroless-Ni coated Al alloy and apply the SPDT technique to the manufacturing of ultra precision optical components of metal aspheric reflector.

• 한국기계가공학회지
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• 제11권2호
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• pp.1-6
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• 2012

Recent ultra-precision machining systems have nano-scale resolution, and can machine various shapes of complex structures using five-axis driven modules. These systems are also multi-functional, which can perform various processes such as planing, milling, turning et al. in one system. Micro machining technology using these systems is being developed for machining fine patterns, hybrid patterns and high aspect-ratio patterns on large-area molds with high productivity. These technology is and will be applied continuously to the fields of optics, display, energy, bio, communications and et al. Domestic and foreign trends of micro machining technologies for flat molds were investigated in this study. Especially, we focused on the types and the characteristics of ultra-precision machining systems and application fields of micro patterns machined by the machining system.

• 한국기계가공학회지
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• 제4권2호
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• pp.31-36
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• 2005

Machining technique for optical crystals with single point diamond turning tool is reported in this paper. The main factors influencing the machined surface quality are studied and regularities of machining process are drawn. Optical crystals have been known to more and more important applications in the field of modern optics. Ge is more brittle material of poor machinability. The traditional machining method is polishing which has many shortcomings such as low production efficiency, poor ability to be automatically controlled and edge effect of the workpiece. The purpose of our research is to find the optimum machining conditions for ductile cutting of Ge and apply the SPDTM technique to the manufacturing of ultra precision optical components of Ge. As a result, the surface roughness is the best when cutting speed is 180m/min, feed rate is 2mm/min, depth of cut is $0.5{\mu}m$ and nose radius of tool is 0.8mm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.891-894
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• 1997

The asphericals lenses are used as objective lens of optical pickup. To examine the design factor the sample product is made before manufacturing of injection mould of lens. The optimum cutting condition of PMMA lens sample with ultra precision SPDT, he main spindle sped, the depth of cut, the feedrate are found. The demanded surface roughness 10nm Ra, aspherical form error 0.5${\mu}{\textrm}{m}$ P-V for aspherical lens of optical data storage device are satisfied.

• 한국정밀공학회지
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• 제30권12호
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• pp.1303-1312
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• 2013

We report an ultra-precision lathe designed to machine micron-scale features on a large-area roll mold. The lathe can machine rolls up to 600 mm in diameter and 2,500 mm in length. All axes use hydrostatic oil bearings to exploit the high-precision, stiffness, and damping characteristics. The headstock spindle and rotary tooling table are driven by frameless direct drive motors, while coreless linear motors are used for the two linear axes. Finite element method modeling reveals that the effects of structural deformation on the machining accuracy are less than $1{\mu}m$. The results of thermal testing show that the maximum temperature rise at the spindle outer surface is approximately $0.5^{\circ}C$. Finally, performance evaluations of the error motion, micro-positioning capability, and fine-pitch machining demonstrate that the lathe is capable of producing optical-quality surfaces with micron-scale patterns with feature sizes as small as $20{\mu}m$ on a large-area roll mold.