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Magnification, Resolution and Illumination. Cell Biology: Magnification and Illumination. Let's take a look at the secret life inside our cells. How large are cells?. Let's put things into perspective. Size is relative…. Is magnification all that matters?Magnification versus Resolution.
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Cell Biology: Magnification and Illumination • Let's take a look at the secret life inside our cells...
How large are cells? Let's put things into perspective....
Is magnification all that matters?Magnification versus Resolution • Is there a limit to magnification? • Does magnification improve resolution? • Resolution of a microscope is its ability to separate small objects which are cose together • Resolution is determined by light/(electron) wavelength; the shorter the wavelength, the higher the resolution • Light microscope resolution is 0.2 μm • Electron microscope resolution is 1 ηm • Scanning Tunnel microscope resolution is 0.01 ηm length 0.01 ηm depth
Light microscope: Magnification Normal maximum magnifications of ocular and objective lenses are 10X and 100X respectively, giving overall maximal magnification of X 1000
Modern Illumination techniques used in light microscopy These techniques modify the light path to generate improved contrast: • Phase contrast micrcoscopy • Cross-polarised (confocal) light microscopy • Dark field microscopy • Fluorescent microscopy
Phase contrast microscopy • Improved contrast, allowing identification of structures in living cells • Allowed us to understand cell division • Won its inventor, Franz Zernike, the NOBEL PRIZE in 1951 • Nobel Prize link to Phase microscope: • Phase Nobel
Contrast Microscopy • Fluorescence contrast techniques • Immunofluorescence techniques • Here is a whole gallery of beautiful images: • Fluorescence Gallery • Cell fluorescence
Electron Microscopy! • Follows the same principles as light microscopy, but shines a beam of electrons rather than light particles • The lower ‘wavelength’ of the electron beam allows incredible resolution • Can visualise particles to the order of a few angstom (10-10m)
Transmission Electron Microscopy • Wellcome scanning microscope • Designed by Ernst Ruska (Heidelberg) in 1938 • He won the Nobel Prize just before his death, in 1986 • First electron microscope was built in Toronto in 1938
Scanning Electron Microscope • Scanning Electron microscope
Scanning Tunneling Microscope • Sharing a Nobel Prize • Scanning tunneling microscopes