RESUMO
Scanning a point light source in close proximity over a sample and recording the scattered or transmitted light intensity point by point allows one to record optical images with a resolution not limited by diffraction. An overview of this technique called scanning near-field optical microscopy (SNOM or NSOM) is given with emphasis on cell- and microbiology. After an introduction, where the basic features of the technique are explained, illustrative examples are presented, such as a HeLa cell, fluorescence labelled human chromosomes, super resolution fluorescence imaging, single molecule imaging and fluorescence resonance energy transfer between a single pair of dye molecules.
Assuntos
Microscopia/instrumentação , Microscopia/métodos , Cromossomos Humanos , Corantes Fluorescentes , Células HeLa/ultraestrutura , Humanos , Hibridização in Situ Fluorescente , Técnicas Microbiológicas/instrumentação , Microscopia de Força Atômica/instrumentação , Microscopia de Força Atômica/métodos , Microscopia Eletrônica de Varredura/instrumentação , Microscopia Eletrônica de Varredura/métodos , Biologia Molecular/métodos , Espectrometria de Fluorescência/métodosRESUMO
The length of the molten zone determines the length of pulled optical fibre tips. Tips produced by laser or filament heating are rather lengthy. By using a foil heater the taper length can be shortened and cone angles in the order of 30 degrees can reproducibly be obtained. For varying the drawing force there is an optimum temperature range where the taper shape is monotonic for the whole tip. The tip end diameter is well below 100 nm for optimized pulling conditions.