• 한국광학회지
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• 제10권3호
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• pp.221-225
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• 1999

레이저선속의 퍼짐각을 개선하기 위하여 공진기 내부에 선속분할기를 갖는 양영역 공초점 불안정공진기 구리증기레이저를 구성하였다. 기하광학적 배율 M=30인 공진기에서 0.15 mard의 최소 퍼짐각을 얻었고, M=60인 공진기를 사용하여 0.1 mard 의 값을 얻을 수 있었다. 퍼짐각 개선과 관련하여 상대적인 원거리 출력밀도가 최대 130배 증가된 레이저 출력을 얻을 수 있었으며, 자체잠김현상을 보이는 펄스 형태의 레이저 발진이 관측되었다.

• International Journal of Precision Engineering and Manufacturing
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• 제9권3호
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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.

• Restorative Dentistry and Endodontics
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• 제29권5호
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• pp.423-429
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• 2004

The purpose of this study was to evaluate the effect of multiple application of all-in-one dentin adhesive system on microtensile bond strength using confocal laser scanning microscope and microtensile bond strength test. Flat occlusal dentin surfaces were prepared using low-speed diamond saw. In group I, Scotchbond Multipurpose (SM) was applied by manufacturer's recommendation. In group II, after Adper Prompt L-Pop was applied for 15s and light cured for 10s. the second coat was re-applied and light-cured. In group III, after light-curing the second layer. the third coat was re-applied and light-cured. Specimens bonded with a resin-composite were sectioned into resin-dentin stick for measuring the adhesive layer thickness by confocal laser scanning microscope and evaluating micro-tensile bond strength. The adhesive layers of three-step dentin adhesive system. 3 coats of Adper Prompt L-Pop had significantly thicker than SM. 2 coats of Adper Prompt L-Pop (p < 0.05). However. there was no significant differences in bond strengths between SM and 3 coats of Adper Prompt L-Pop (p > 0.05). And SM. 3 coats of Adper Prompt L-Pop had significantly higher than 2 coats of Adper Prompt L-Pop in bond strengths (p < 0.05).

• Restorative Dentistry and Endodontics
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• 제28권5호
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• pp.392-401
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• 2003

The purpose of this study was to evaluate the penetration pattern of dentin adhesives according to the orientation of dentinal tubules with confocal laser scanning microscopy. Specimens having perpendicular. parallel and oblique surface to dentinal tubules were fabricated. The primer of dentin adhesives (ALL $BOND^{\circledR}{\;}2,{\;}CLEARFIL^{TM}$ SE BOND and PQ1) was mixed with fluorescent material. rhodamine B isothio-cyanate (Aldrich Cherm. CO., Milw., USA), It was applied to the specimens according to the instructions of manufactures. The specimens were covered with composite resin (Estelite, shade A2) and then cut to a thickness of 500$\mu\textrm{m}$ with low speed saw (Isomet^{TM}, Buehler. USA). The adhesive pattern of dentin adhesives were observed by fluorescence image using confocal laser scanning microscopy. The results were as follows. 1. For the groups with tubules perpendicular to bonded surface. funnel shape of resin tag was observed in all specimen. However. resin tags were more prominent in phosphoric acid etching system (ALL $BOND^{\circledR}$ 2 and PQ1) than self etching system ($CLEARFIL^{TM}$ SE BOND). 2. For the groups with tubules parallel to bonded surface. rhodamine-labeled primer penetrated into peritubular dentin parallel to the orientation of dentinal tubules. But rhodamine-labeled primer of PQ1 diffused more radially into surrounding intertubular dentin than other dentin adhesive systems. 3. For the groups with tubules oblique to bonded surface. resin tags appeared irregular and discontinuous. But they penetrated deeper into dentinal tubules than other groups.

• 한국광학회지
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• 제22권1호
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• pp.46-52
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• 2011

본 연구에서는 레버 증폭 구조를 이용한 플렉서 기반의 나노 스테이지를 설계, 제작하였다. 제작된 나노 스테이지를 샘플 스테이지로 채용한 공초점현미경을 개발하였다. 2차원 이미징의 구현을 위해서, 기존의 공초점현미경은 레이저를 이미징 평면상에 스캐닝하는 방식으로 구현된다. 본 연구에서는 백 나노미터의 구동정밀도를 가지는 나노 스테이지 위에 놓인 샘플을 2차원으로 스캐닝하면서 2차원 이미지를 구현할 수 있는 공초점현미경을 개발하였다. 플렉서 기반의 나노 스테이지는 이중 판스프링, 변위증폭 레버, PZT 엑추에이터 그리고 변위 센서로 구성 되어 있다. 스테이지의 구동 성능 해석을 위해 상용 유한요소 해석 프로그램을 이용하였다. 현미경에 사용되는 광원은 적색광 레이저이며, 레이저는 여러 광학요소를 거쳐 샘플스테이지의 샘플에 입사되고, 반사된 빛은 광센서인 PMT(Photo Multiplying Tube)로 계측되게 된다. 계측된 빛의 크기를 이용하여서 2차원 이미징을 구현하였다. 개발된 공초점 현미경으로 생쥐 귀의 피부조직을 관찰하여 현미경의 이미징 성능을 검증하였다. 설계된 샘플 스테이지는 기존의 공초점 현미경의 기계적인 Beam 스캐너를 대신함으로써 현미경의 광경로 및 전체시스템을 간소화 하였다.

• 한국정밀공학회지
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• 제26권6호
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• pp.50-58
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• 2009

Micro laser fabrication techniques can potentially be used for the manufacture of microstructures on the thin flat surfaces with large diameter that are frequently used in semiconductor industries. However, the large size of wafers can cause the degraded machining accuracy of the surface because it can be tilted or distorted by geometric errors of machines or the holding fixtures, etc. To overcome these errors the off-line focusing error compensation method is proposed. By using confocal autofocus system, the focusing error profile of machined surface is measured along the pre-determined path and can be compensated at the next machining process by making the corrected motion trajectories. The experimental results for silicon wafers and invar flat surfaces show that the proposed method can compensate the focusing error within the level of below $6.9{\mu}m$ that is the depth of focus required for the laser micromachining process.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.263-268
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• 2004

In the present study, a Nd;YAG Laser (pulse type) was used to emit ultrasonic signals to a test material. In addition, a total ultrasonic investigation system was designed by adopting a Fabry-Perot interferometer, which receives ultrasonic signals without any contact. For non-destructive test SM45C, which contains some flaws was used as a test material. Because it is easy to align light beam in receiver, and the length of the light beam does not change much even if convex mirror leans towards one side, confocal Fabry-Perot interferometer, which has stable frequency, and PI control are used to correct interfered and unstable signals from temperature, fluctuation and time shift of laser frequency. Stable signals are always obtained by the feedback of PI circuit signals in the confocal Fabry-Perot interferometer. The type, size and position of flaws inside the test material were examined by achieving the stabilization of an interferometer. This study presented a useful method, which could quantitatively investigate the fault of objects by using a Fabry-Perot interferometer.

• Journal of the Optical Society of Korea
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• 제9권2호
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• pp.49-53
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• 2005

We report a new configuration of a reflection-type confocal scanning optical microscope system for measuring the refractive index profile of an optical waveguide. Several improvements on the earlier design are proposed; a light emitting diode (LED) at 650 nm wavelength instead of a laser diode (LD) or He-Ne laser is used as a light source for better index precision, and a simple longitudinal linear scanning and curve fitting techniques are adapted instead of a servo control for maintaining an optical confocal arrangement. We have obtained spatial resolution of 700 nm and an index precision of $2\times10^{-4}$. To verify the system's capability, the refractive index profiles of a conventional multimode fiber and a home-made four-mode fiber were examined with our proposed measurement method.

• 한국광학회:학술대회논문집
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• 한국광학회 2007년도 하계학술발표회 논문집
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• pp.71-72
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• 2007

• International Journal of Precision Engineering and Manufacturing
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• 제7권4호
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• pp.3-7
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• 2006

Confocal scanning microscopy is a measurement technique used to observe micrometer and sub-micrometer features due to its high resolution, nondestructive properties, and 3D surface profiling capabilities. The design, implementation, and performance test of a confocal scanning microscopy system are presented in this paper. A short-wavelength laser (405 nm) and an objective lens with a high numerical aperture (0.95) were used to achieve the desired high resolution, while the x- and y-axis scans were implemented using an acousto-optic deflector and galvanomirror, respectively. An objective lens with a piezo-actuator was used to scan the z-axis. A spatial resolution of less than 138 nm was achieved, along with successful 3D surface reconstructions.