• Current Optics and Photonics
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• v.5 no.5
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• pp.524-531
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• 2021

In an integral-imaging microscopy (IIM) system, a microlens array (MLA) is the primary optical element; however, surface errors impede the resolution of a raw image's details. Calibration is a major concern with regard to incorrect projection of the light rays. A ray-tracing-based calibration method for an IIM camera is proposed, to address four errors: MLA decentering, rotational, translational, and subimage-scaling errors. All of these parameters are evaluated using the reference image obtained from the ray-traced white image. The areas and center points of the microlens are estimated using an "8-connected" and a "center-of-gravity" method respectively. The proposed approach significantly improves the rectified-image quality and nonlinear image brightness for an IIM system. Numerical and optical experiments on multiple real objects demonstrate the robustness and effectiveness of our proposed method, which achieves on average a 35% improvement in brightness for an IIM raw image.

• Applied Microscopy
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• v.50
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• pp.22.1-22.6
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• 2020

In-situ transmission electron microscopy (TEM) holders that employ a chip-type specimen stage have been widely utilized in recent years. The specimen on the microelectromechanical system (MEMS)-based chip is commonly prepared by focused ion beam (FIB) milling and ex-situ lift-out (EXLO). However, the FIB-milled thin-foil specimens are inevitably contaminated with Ga⁺ ions. When these specimens are heated for real time observation, the Ga⁺ ions influence the reaction or aggregate in the protection layer. An effective method of removing the Ga residue by Ar⁺ ion milling within FIB system was explored in this study. However, the Ga residue remained in the thin-foil specimen that was extracted by EXLO from the trench after the conduct of Ar⁺ ion milling. To address this drawback, the thin-foil specimen was attached to an FIB lift-out grid, subjected to Ar⁺ ion milling, and subsequently transferred to an MEMS-based chip by EXLO. The removal of the Ga residue was confirmed by energy dispersive spectroscopy.

• Applied Microscopy
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• v.42 no.3
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• pp.147-150
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• 2012

A recently introduced helium ion microscopy (HIM) was employed to observe uncoated pine leaf specimens. Adult leaves were collected from the seedlings of Pinus densiflora and P. rigida, air-dried at room temperature, and observed by HIM without metal coating. Ovoid or round stomata and distinct Florin rings could be discerned. The epicuticular waxes were present in the epistomatal chambers and Florin rings of stomata on the leaf surface. The epicuticular waxes were mostly straight, cylindrical, and ca. 1 ${\mu}m$ in length. The epistomatal chambers of P. rigida were filled with the epicuticular waxes, whereas those of P. densiflora were not filled with the epicuticular waxes. Based on their micromorphology, the epicuticular wax structures of the pine species were identified as tubules. These results suggest that the HIM could be used for the investigation of the plant stomata and epicuticular waxes of uncoated plant leaves. Due to the smaller ion probe and interaction volume, the HIM has advantages over conventional field emission scanning electron microscopy in terms of image resolution and charge neutralization.

• Progress in Superconductivity
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• v.13 no.1
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• pp.28-33
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• 2011

Distribution of the local critical temperature and current density in YBCO coated conductors were analyzed using Low-temperature Scanning Laser and Hall Probe Microscopy (LTSLHPM). We prepared YBCO coated conductors of various bridge types to study the spatial distribution of the critical temperature and the current density in single and multi bridges. LTSLHPM system was modified for detailed linescan or two-dimensional scan both scanning laser and scanning Hall probe method simultaneously. We analyzed the local critical temperature of single and multi bridges from series of several linescans of scanning laser microscopy. We also investigated local current density and hysteresis curve of single bridge from experimental results of scanning Hall probe microscopy.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.580-582
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• 2005

거리가 상당히 먼 곳에서 고가의 장비를 사용하기 위해서는 사용할 연구 인력이 직접 와야 하는 많은 시간적 비용적 문제가 발생한다. 특히 본원에 장비되어 있는 초고전압 투과전자현미경(High Voltage Electron Microscopy - 이하 HVEM)의 경우 고가의 장비로 지역마다 기기를 구비할 수 없어 사용자는 직접 장비가 있는 연구실까지 와서 사용해야 한다. HVEM은 1천만 배율의 성능을 가진 국내 유일은 물론 전 세계적으로도 손꼽히는 고성능의 투과전자현미경으로 NT(Nano Technology), BT(Bio Technology) 연구에 있어서 핵심적인 역할을 하는 청단 연구기기이다. 따라서 본 논문에서는 그리드 컴퓨터 기술을 이용하여 HVEM을 원격제어 하는 시스템을 구축하였다.

• Current Optics and Photonics
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• v.2 no.6
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• pp.595-605
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• 2018

The two-photon process of microscopy provides good spatial resolution and optical sectioning ability when observing quasi-static endogenous fluorescent tissue within an in vivo animal model skin. In order to extend the use of such systems, we developed a two-photon laser scanning microscopy system capable of also capturing $512{\times}512$ pixel images at 90 frames per second. This was made possible by incorporating a 72 facet polygon mirror which was mounted on a 55 kRPM motor to enhance the fast-scan axis speed in the horizontal direction. Using the enhanced temporal resolution of our high-speed two-photon laser scanning microscope, we show that rapid processes, such as fluorescently labeled erythrocytes moving in mouse blood flow at up to 1.2 mm/s, can be achieved.

• Current Optics and Photonics
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• v.4 no.3
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• pp.193-199
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• 2020

In this paper we propose a dark-field digital holographic microscopy system based on 360-degree oblique illumination. This setup is constructed without using a dark-field objective. The principle of 360-degree oblique illumination of vortex beam and dark-field digital holographic microscopy are introduced theoretically and experimentally. By analyzing the reconstructed image of a dark-field digital hologram of a USAF 1951 target, it is proved that the imaging resolution can be improved by this method. And also, comparison and analysis are made on the reconstructed image of a bright-dark field digital hologram of a pumpkin stem slice, the result shows that the imaging contrast is also enhanced with this method, and it is effective for dark-field digital holographic microscopy imaging of large transparent biological samples.

• Applied Microscopy
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• v.38 no.3
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• pp.275-278
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• 2008

Electron tomography (ET) is an electron microscopic technique for obtaining a 3-D image from any electron microscopy specimen and its application in biomedical science has been increased thanks to development of electron microscopy and related technologies during the last decade. There are few researches on ET in Korea during this period. Although the importance of ET has been recognized recently by many researchers, initial approach to electron tomographic research is not easy for beginners. The 4th International Congress on Electron Tomography (4 ICET) was held on Nov $5{\sim}8$, 2006, at San Diego. The program dealt instrumentation, reconstruction algorithm, visualization/quantitative analysis and electron tomographic presentation of biological specimen and nano particles. 1 have summarized oral presentations and analyzed the posters presented on the meeting. Cryo-electron microscopic system was popular system for ET and followed conventional transmission electron microscopic system. Cultured cell line and tissue were most popular specimens analyzed and microorganisms including bacteria and virus also constituted important specimens. This analysis provides a current state of art in ET research and a guide line for practical application of ET and further research strategies.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.4
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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.

• Journal of ILASS-Korea
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• v.21 no.2
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• pp.88-94
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• 2016

In this study digital holographic microscopy system for measurements of 3-D velocities of particles in MR fluid is developed. Holograms are recorded using either a CCD camera with a double pulse laser or a high-speed camera with a continuous laser. To process recorded holograms, the correlation coefficient method is used for focal plane determination of particles. To remove noise and improve the quality of holograms and reconstructed images, a Wiener filter is adopted. The two-threshold and image segmentation methods are used for binary image transformation. For particle pairing, the match probability method is adopted. The developed system will be applied to measurements of the characteristics of unsteady 3-D particle velocities in MR fluids through the next stage of this study.