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Microscopic techniques
Microscopy involves using microscopes to produce magnified images of small structures. There are two main types of microscopes - light microscopes, which use visible light and lenses, and electron microscopes, which use electron beams. Light microscopes can be brightfield, darkfield, phase contrast, or fluorescent depending on how they illuminate the sample. Electron microscopes like SEM and TEM provide higher magnification but produce black and white images based on scattered or transmitted electrons. Scanning probe microscopy also provides atomic-scale topography images.
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Microscopic techniques
- 1. Microscopy Types of microscopes Lightmicroscopes – UV, Dark field, Phase contrast, Fluorescent and Electron microscope. Dr. S. PARTHASARATHY, M.Sc. (Agri)., Ph.D. Assistant Professor (Plant Pathology)
- 3. Introduction • Microscopy isany technique for producing visible images of structures. • A microscope is an instrument designed to make fine details visible. • Light Microscope • Electron Microscope • Scanning Probe Microscope
- 8. • The opticalmicroscope is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. • Optical and illumination systems are its basic elements.
- 10. Types of lightmicroscope – Bright-field microscope – Dark-field microscope – Phase-contrast microscope – Fluorescence microscopes
- 11. Bright field • “normal”wide-field illumination method • bright background • low contrast Dark field • an opaque disc is placed underneath the condenser lens • scattered light • dark background • high contrast (structural details)
- 12. Polarizing microscope Brightfield/Darkfield Stereo Microscope
- 14. Phase contrast • Principle:Different densities and refractive indices of different parts of cells.
- 16. Fluorescent microscope • Fluorescentcompound which absorbs light at one wavelength and then emits light at longer wavelength.
- 17. Epi-Fluorescence microscope with3 filters 4 Semi Apochromatic objective lenses Inverted Fluorescence Compound Microscope Inverted Microscopes have the condenser and light source above the stage and the objective lenses below.
- 18. SEM Scanned with anelectron beam, and the reflected (or back-scattered) beam of electrons is collected, then displayed at the same scanning rate on a cathode ray tube (similar to a CRT television screen).
- 19. TEM Contrasts in theimage are produced by differences in beam scattering or diffraction produced between various elements of the microstructure.
- 20. Scanning electron microscopeTransmission electron microscope Morphology character Internal structure Electron beams scan over the sample Electron beams pass through the sample Magnification 1,00,00 0X Magnification 5,00,000 X Three dimensional black and white images Produce two dimensional black and white structure Based on scattered electrons or produce images by detecting secondary electron which are emitted from the surface of the sample Based on the transmitted electron two produce image
- 22. Scanning Probe Microscopy •Generates a topographical map, on an atomic scale, that is a representation of surface features and characteristics of the specimen being examined. • Scanning tunneling microscopy (STM), Atomic force microscopy (AFM), Near-field scanning optical microscopy. • Three-dimensional magnified images are generated that provide topographical information about features of interest.
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