• 한국세라믹학회지
• /
• 제36권4호
• /
• pp.417-424
• /
• 1999

Laser lapping of diamond films is performed with focused beam of copper vapor laser. Both spherical and rod-shape laser beam are used. Diamond surface is scanned at various scan speeds(0,125, 0.5, 0.75 mm/sec) and baem shifts (5, 10, 20, 40, 100$\mu\textrm{m}$) At 0.125 mm/sec 10$\mu\textrm{m}$ scan condition the level difference of di-amond surface of about 700$\mu\textrm{m}$ over 20 mm is reduced to 200$\mu\textrm{m}$ In addition surface roughness is also im-proved from 3.53$\mu\textrm{m}$ to 2.47$\mu\textrm{m}$ at 5$\mu\textrm{m}$ beam shift. But at higher beam shift than 10$\mu\textrm{m}$ laser scan makes the surface rougher which is considered to be due to the non uniform spatial distribution of laser en-ergy. It is concluded that homogenized laser beam with high average power is needed for large area laser lapping of diamond films at appreciable rates.

• 대한기계학회논문집A
• /
• 제35권1호
• /
• pp.107-114
• /
• 2011

본 논문에서는 나노 래핑 표면의 형상과 레이저산란 패턴 사이의 실험적 모델링에 관한 연구를 하였다. 우선, 반사표면에서 나타나는 산란광 속성들을 고찰하여 암시야 기반의 레이저산란 검사 메커니즘을 구성하였다. 이 메커니즘을 이용한 레이저산란 패턴 분석의 경우, 나노 래핑 표면 형상으로부터 산란된 레이저산란 성분은 불규칙하게 사선형태로 교차됨을 알 수 있다. 또한, 실험 계획법을 기반으로 도출된 매개변수로 적용된 최적의 레이저산란 영상에서 나노 래핑 표면 거칠기와 레이저산란 성분 사이의 상관관계를 회귀분석법을 이용하여 수학적 모델링을 시도 하였다. 이 모델의 검증을 위해 나노 래핑 표면 3 종류의 거칠기에 대해 50 번의 반복실험을 수행한 결과, 제시된 수학적 모델은 실제 거칠기 값에 근접하게 추정할 수 있음을 보였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2010년도 추계학술대회 논문집
• /
• pp.737-738
• /
• 2010

• 한국정밀공학회지
• /
• 제19권11호
• /
• pp.211-220
• /
• 2002

Optical disk drives read information by replacing a laser beam on the disk track. As information has become larger, the more accurate position control of a laser beam is necessary. In this paper, we report the analysis and fabrication of the micro mirror for optical disk drivers. A coupled simulation of gas flow and structural displacement of the micro mirror using the Finite-Element-Method is applied to this. The mirror was fabricated by using MEMS technology. Especially, the process using the lapping and polishing step after the bonding of the mirror and electrode plates was employed for the Process reliability. The mirror size was 2.5mm${\times}$3mm and it needed about 35V for displacement of 3.2 ${\mu}$.

• 전자공학회논문지A
• /
• 제29A권9호
• /
• pp.36-45
• /
• 1992

The Modified Multi-Quantum Well(MMQWAl) structures have been grown by Mental-Organic chemical Vapor Deposition(MOCVD) method and stripe type MMQW laser diodes have been investigated. In the case of GaAs/AlGaAs superlattice and quantum well growth by MOCVD, the periodicity, interface abruptess, Al compositional uniformity and layer thickness have been confirmed though the shallow angle lapping technique, double crystal x-ray diffractometry (DCXD) and photoluminescence (PL) measurement. stripe-type MMQW laser diodes have been fabricated using the process technology of photolithography, chemical etching, ohmic contact, back side removing and cleaving. As the result of the electrical and opticalmeasurement of these laser diodes, we have achieved the series resistance of $1[\Omega}~2{\Omega}$ by current-voltage measurements, the threshold current of 200-300mA by currnt-light measurements and the lasing wavelength of 8000-8400$\AA$ by lasing spectrum measurements.

• Tribology and Lubricants
• /
• 제26권6호
• /
• pp.311-316
• /
• 2010

Surface texturing of micro dimple or pore-shaped pattern was prepared using a fiber laser system. Surface texturing was designed to have a square pattern with a particular pitch distance for each corresponding density of 5, 10, 20, and 30%. Thermal damages such as bulges and burrs formed during laser irradiation were observed around the dimples. Thermal damages were later removed by lapping using alumina particles of $0.3{\mu}m$ in diameter. Oscillating friction tests were performed against heat-treated high speed steels under lubricated condition. The lubricant used was SAE 5W-30 automotive engine oil. Normal contact pressure and oscillating frequency was 0.28 MPa and 20 Hz, respectively. The tests were continued for 20 minutes, and friction plots were recorded for examination. Results revealed that the coefficient of friction was lowered regardless of texturing density. Moreover, the lowest coefficient of friction was obtained for 10% density texturing. It is attributed to increased lubricity due to the introduction of surface texturing. In addition, it is concluded that the optimum texturing density and pattern must be found for the best lubricity and low friction.

• 한국정밀공학회지
• /
• 제18권11호
• /
• pp.51-57
• /
• 2001

A light beam reflected from a machined surface generally containes information concerning about its surface roughness. This study examines and proposes a surface roughness measurement technique for on-machine measurement of machined surfaces. The technique is based on the measurement of a reflected laser beam pattern and the statistical analysis of its light intensity distribution. The surface roughness was found to be closely related to the standard deviation of the light intensity on the primary axis of the reflected pattern. An image acquisition device is made up of a laser diode, a half mirror, a screen, and a CCD camera. The exact image with the primary and secondary axes of a reflected laser beam pattern is calculated through such image processing algorithm as thresholding, edge detection, image rotation, segmentation, etc. A median filter and a surrounding light correction algorithm are improve the image quality and reduce the measuring error. Using the developed measuring device the effect of screen materials and workpiece and workpiece materials was investigated. Experimental results regarding to relatively high-quality surfaces machined by grinding, polishing, lapping processes have shown the measurement error is within 10% in the range of $0.1{mu}m~0.8{\mu}m R_q.$Therefore, the proposed method is thought to be effectively used when quick measurements is needed with workpieces fixed on the machine.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.94-97
• /
• 2003

A precise fabrication technology of glass is increasingly demanded fer the latest Industrial applications of spherical lenses. micro-optical components, laser applications and so on. Most of cases, the surface roughness of glass is required to be minute for improving the optical characteristics. Then. the machining characteristics of SF-5 glass and quarts glass were studied by using the ELID grinding process to get mirror surface and productivity compared with a general lapping process. A rotary type grinder with ELID generator was used to make the mirror surface of glass and a Mitutoyo surface tester and a nano-hardness tester were also used to measure the grinded surface or glass. As the results of experiments. they showed that the surface roughness(Ra) of SF-5 glass was under 7.8 nm and that of quartz glass was under 3.0 nm using the # 8000 grinder. So, the possibility of highly efficient and accurate surface for optical components can be achieved by the ELID grinding process.

• 센서학회지
• /
• 제11권1호
• /
• pp.39-47
• /
• 2002

광 저장장치는 디스크 트랙에 레이저빔을 위치시켜 정보를 저장한다. 정보의 용량이 증대되면서 좀더 높은 저장 밀도를 요구하게 되었고, 그만큼 정밀한 레이저빔의 위치제어가 필요하게 되었다. 본 논문에서는 광 저장장치용 정전형 마이크로 미러를 MEMS기술을 이용해 제조하고 그 특성을 조사하였다. 마이크로 미러는 벌크 마이크로머시닝 기술에 의하여 제조되었으며, 특히 접합공정이 이루어지고 난 후에 연마공정에 의해서 실리콘 웨이퍼의 두께 및 미러면의 형태를 형성하는 공정을 적용함으로서 제현성을 높였다. 제작된 미러의 크기는 $3.0mm{\times}2.5mm$ 이고, 35V에서 변위는 $3.2{\mu}m$ 였다.