• 한국공작기계학회논문집
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• 제16권5호
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• pp.115-121
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• 2007

Phase contrast imaging in atomic force microscopy showed a promise as an effective tool for better understanding of micromechanical properties of surfaces at nano scale. A qualitative estimation model for phase contrast images obtained with a tapping mode AFM was developed. This investigation demonstrated the high efficiency of combined analysis of topography and phase contrast images for characterizing nanosurfaces. Phase contrast images allowed estimation of relative stiffness(elastic modulus) of the sample surface. The phase contrast images revealed a significant inhomogeneity of the nano scale worn surfaces. Phase contrast images are also capable of revealing the formation of tribofilms.

• Journal of the Optical Society of Korea
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• 제19권1호
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• pp.22-28
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• 2015

We propose a new method for improving the phase contrast of a multiphase digital holographic microscope using a spatial light modulator (SLM). Using the SLM as the annulus, our method improves the light contrast of the object edge to achieve higher accuracy. We demonstrate a digital holographic microscopy technique that provides a 30% improvement in the phase contrast compared to conventional microscopy, which utilizes a mechanical annulus. The phase-contrast improvement allows the 3D reconstructed hologram to be determined more precisely.

• Tribology and Lubricants
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• 제18권2호
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• pp.138-143
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• 2002

Abstract - Tribofilms formed on won surface protect the DLC coating surface and decrease the fiction coefficient. However it is very difficult to evaluate their micromechanical properties due to their small thickness, inhomogeneity and discontinuity. The phase contrast images in tapping mode atomic farce microscopy allow an estimation of inhomogeneity in micromechanical properties of the sample surface. The purpose of this investigation is to demonstrate how the phase contrast images contribute to the characterization of thin tribofilms.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.299-304
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• 2001

Tribofilms formed on worn surface protect the DLC coating surface and decrease the friction coefficient. However it is very difficult to evaluate their micromechanical properties due to their small thickness, inhomogeneity and discontinuity. The phase contrast images in tapping mode atomic force microscopy allow an estimation of inhomogeneity in micromechanical properties of the sample surface. The purpose of this investigation is to demonstrate how the phase contrast images contribute to the characterization of thin tribofilms.

• 대한의용생체공학회:의공학회지
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• 제33권4호
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• pp.169-176
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• 2012

Tumor cell morphology is closely related to its migratory behaviors. An active tumor cell has a highly irregular shape, whereas a spherical cell is inactive. Thus, quantitative analysis of cell features is crucial to determine tumor malignancy or to test the efficacy of anticancer treatment. We use 3D time-lapse phase-contrast microscopy to analyze single cell morphology because it enables to observe long-term activity of living cells without photobleaching and phototoxicity, which is common in other fluorescence-labeled microscopy. Despite this advantage, there are image-level drawbacks to phase-contrast microscopy, such as local light effect and contrast interference ring. Therefore, we first corrected for non-uniform illumination artifacts and then we use intensity distribution information to detect cell boundary. In phase contrast microscopy image, cell is normally appeared as dark region surrounded by bright halo ring. Due to halo artifact is minimal around the cell body and has non-symmetric diffusion pattern, we calculate cross sectional plane which intersects center of each cell and orthogonal to first principal axis. Then, we extract dark cell region by analyzing intensity profile curve considering local bright peak as halo area. Finally, we calculated the Fourier descriptor that morphological characteristics of cell to classify tumor cells into active and inactive groups. We validated classification accuracy by comparing our findings with manually obtained results.

• Current Optics and Photonics
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• 제7권5호
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• pp.537-544
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• 2023

Differential phase contrast (DPC) microscopy, a central quantitative phase imaging (QPI) technique in cell biology, facilitates label-free, real-time monitoring of intrinsic optical phase variations in biological samples. The existing DPC imaging theory, while important for QPI, is grounded in paraxial diffraction theory. However, this theory lacks accuracy when applied to high numerical aperture (NA) systems that are vital for high-resolution cellular studies. To tackle this limitation, we have, for the first time, formulated a nonparaxial DPC imaging equation with a transmission cross-coefficient (TCC) for high NA DPC microscopy. Our theoretical framework incorporates the apodization of the high NA objective lens, nonparaxial light propagation, and the angular distribution of source intensity or detector sensitivity. Thus, our TCC model deviates significantly from traditional paraxial TCCs, influenced by both NA and the angular variation of illumination or detection. Our nonparaxial imaging theory could enhance phase retrieval accuracy in QPI based on high NA DPC imaging.

• Applied Microscopy
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• 제33권3호
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• pp.169-178
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• 2003

영상이론과 회절 이론을 같은 비중으로 다루고 이들과의 관계를 나타내는 wave optics 이론을 소개하였다. 결맞는 파동 이론과 결 안맞는 파동이론 사이의 차이를 나타내고 Abbe이론과 여러 가지 phase contrast 이론들을 small angle 근사로 접근하였다. 마지막으로 다중 성분 시스템에 대한 파동 광학의 수학적인 방법의 적용을 소개하였다.

• 한국광학회지
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• 제34권6호
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• pp.261-268
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• 2023

본 연구에서는 간단한 구조의 층밀림 간섭계 기반의 정량적 위상 이미징을 위한 미분 간섭 현미경 모듈을 제안한다. 제안하는 모듈은 복굴절성과 편광 광 분할기의 특성을 갖는 기하 위상 소자 중의 하나인 편광 격자를 이용하여 층밀림 간섭계 구조로 구성되고, 편광 카메라를 통해 획득된 4개의 편광 영상으로 정량적인 위상차 영상뿐만 아니라 일반적인 명시야 현미경 영상을 동시에 추출할 수 있다. 또한, 제안하는 모듈의 실시간 영상 획득 가능성, 안정성 및 소형화로 인해 기존의 현미경에 편리하게 적용할 수 있다. 제안하는 시스템을 검증하기 위해 다양한 시편에 대한 명시야 영상 및 위상차 영상을 획득하였고, 또한 이들 영상들을 합성하여 보다 가독성이 높은 시편 영상을 획득하였다.

• 한국광물학회지
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• 제28권2호
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• pp.165-171
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• 2015

부산과 울산의 중심지역에 대해 공기 중의 분진시료를 채취하여, 위상차현미경, 위상차분산현미경, 주사전자현미경 등으로 석면을 분석한 결과, 석면은 검출한계 이하로서 확인되지 않았다. 공기중의 분진시료에는 섬유상물질이 다수 포함되었으나, 이들은 대부분 유기질 섬유인 것으로 나타났다. 무기질 섬유물질로는 암면, 세라믹섬유, 석고 등이 소량 포함되었으며, 비섬유상인 석영, 방해석, 장석등의 광물도 가끔 관찰되었다. 국내의 공기 중 분진의 석면분석은 주로 위상차현미경으로 관찰하는 것으로 규정되어 있으나, 이것만으로는 석면의 식별이 불가능한 것으로 나타났다. 따라서 일본 JIS법과 같이 저온회화 처리 장치에 의한 유기물질 제거 후에 분산염색법으로 석면을 식별하고 계수하는 것이 효율적인 것으로 사료된다.

• Journal of the Optical Society of Korea
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• 제14권2호
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• pp.77-89
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• 2010

Digital holography (DH) is a potentially disruptive new technology for many areas of imaging science, especially in microscopy and metrology. DH offers a number of significant advantages such as the ability to acquire holograms rapidly, availability of complete amplitude and phase information of the optical field, and versatility of the interferometric and image processing techniques. This article provides a review of the digital holography, with an emphasis on its applications in biomedical microscopy. The quantitative phase microscopy by DH is described including some of the special techniques such as optical phase unwrapping and holography of total internal reflection. Tomographic imaging by digital interference holography (DIH) and related methods is described, as well as its applications in ophthalmic imaging and in biometry. Holographic manipulation and monitoring of cells and cellular components is another exciting new area of research. We discuss some of the current issues, trends, and potentials.