TAILIEUCHUNG - HOLOGRAPHY, RESEARCH AND TECHNOLOGIES_2

Tham khảo sách 'holography, research and technologies_2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Part 4 Holographic Applications 10 Quantitative Analysis of Biological Cells Using Digital Holographic Microscopy Natan T. Shaked Lisa L. Satterwhite Matthew T. Rinehart and Adam Wax Department of Biomedical Engineering Fitzpatrick Institute for Photonics Duke University Durham North Carolina 27708 USA 1. Introduction Biological cells are microscopic dynamic objects continuously adjusting their threedimensional sizes shapes and other biophysical features. Wide-field microscopy of cell dynamics can provide a powerful research tool for cell biology studies as well as a potential means for medical diagnosis and monitoring of diseases. Biological cells however are mostly-transparent objects and thus imaging them with conventional intensity-based light microscopy fails to provide adequate optical contrast between the cell and its environment. Although exogenous contrast agents such as fluorescent dyes can be used to solve this problem they might be cytotoxic in the long run and there is a possibility they will influence the cellular behavior. Additionally fluorescent dyes tend to photobleach potentially limiting the imaging time. The contrast problem when imaging biological cells can also be solved by using phase microscopy which records the optical path delays of light passing through the cells and subsequently obtains information on the cellular structure and dynamics without using any exogenous labelling. Since detectors are sensitive to intensity only the phase of the light that has interacted with the cells must first be converted to intensity variations for detection. Widely used methods to achieve this include phase contrast microscopy and differential interference contrast DIC microscopy. However these techniques are not inherently quantitative and present distinct imaging artifacts that typically prevent straightforward extraction of the entire optical path delay profile of the cell. Wide-field digital interferometry WFDI is a label-free holographic technique .

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