Microscopy

clappergappawpawUrban and Civil

Nov 16, 2013 (3 years and 9 months ago)

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Electron Microscopes are scientific
instruments that use a beam of highly
energetic electrons to examine objects
on a very fine scale.


Transmission Electron Microscope
: A
beam of electrons is passed through the
specimen. Electrons that pass through
are used to expose film. Areas of the
specimen that scatter electrons appear
dark. False coloring enhances the
image.


As the light passes through the film, it
interacts with the film & specific areas


Light pass through unobstructed, other
areas absorb light and doesn’t let it pass
through


The light that does go through is hits the
lenses found on the other side


The resulting image is projected onto a
screen



Scanning Electron Microscope
: An
electron beam is scanned across the
surface of the specimen, and electrons
are knocked off the surface. Thus, the
surface topography of the specimen
determines the contrast and the content
of the image. False coloring enhances
the image.


A beam of electrons is produced at the
top of the microscope by an electron
gun.


The electron beam follows a vertical
path through the microscope, which is
held within a vacuum.


The beam travels through
electromagnetic fields and lenses


Which focus the beam down toward the
sample.


Once the beam hits the sample,
electrons.


Detectors collect these X
-
rays, back
scattered electrons, and secondary
electrons


Convert them into a signal that is sent to
a screen similar to a television screen.


This produces the final image.

Organelles of a grain of tobacco

Polio Virus

Gills of a fish

Normal Circulating Human Blood