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8 Cards in this Set
- Front
- Back
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fluorescence microscope |
variation of bright field microscope uses a mercury arc vapor lamp as a source UV to illuminate the specimen -fluorescent will absorb the illuminating light and emit light at longer wavelength and emit light at longer wavelengths in the visible range -a filter is placed b/w the objective and ocular lenses to prevent all but the longer wavelength light passing to the eyepiece -a special condenser is used so that the bg field is dark, thereby resulting in a high contrast fluorescent image |
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confocal microscope
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similar to fluorescence -uses point illumination -by illuminating only the point of focus> unwanted scattered light is reduced -light rom specimen passes through a pinhole aperture that blocks light not coming form the focal point -reducing stray light from sources not at the focal point improves resolution -technique allows 3D images of the sample to be built from viewing thin sections |
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phase conrast microscope |
-living cells can best be viewed with a phase-contrast microscope -the optics of the microscope translate differences b/w the refractive indices of cellular components and the surrounding medium into differences in light intensity |
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darkfield microscope |
-condenser is designed to prevent light from passing to the objective unless it strikes the specimen -bg is dark -the high contrast between the background and the specimen makes it possible to view living unstained specimens |
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electron microscope |
2 types transmission and scanning. -both use magnetic lenses that focus a beam of e- on the specimen -e- used in this fashion generate a wavelength that may be 100,000 times shorter than of visible light -have resolving powers as much as 400 times that of light microscopes and 200,000 times of that of the human eye |
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TEM |
-bombards a thin specimen with e- -depending on their composition> the components of the specimen transmit, absorb or deflect the electrons -image produced on a photographic plate is a visual translation of this interaction of electrons with the specimen -the TEM exposes many secrets of sub cellular structure -gave scientists their first look at the world of viruses & today permits us to see molecules and atoms |
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SEM |
-designed to generate dramatic 3D pictures of surface detail -an e- beam is moved back and forth over the surface of a metal-coated specimen causing the emission of secondary electrons from the specimen -the secondary electrons produce the stunning images characteristic of scanning e- microscopy |
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KOHLER steps |
1. get a microscope, plug it in, turn it on 2. place specimen slide on the stage 3. select the 4X objective and center using the X and Y micrometer knobs 4. focus the specimen using the coarse focus knob 5. adjust the light level with the light intensity knob 6. select the 10X objective 7. refocus the specimen with the coarse and then with the fine focus knob 8. set the iris diaphragm halfway open(.5) 9. stop down the field-limiting aperture 10. adjust the condenser lens using the condenser lens knob to extinguish the chromatic aberration 11. center the illumination with the illumination centering knobs 12. open the field-limiting aperture to view the full field |
