BIO1011 Lecture Notes - Lecture 3: Confocal Microscopy, Phase-Contrast Microscopy, Scanning Electron Microscope
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•There are two key properties of a microscope.
-Magniﬁcation - enlarging the image
-Resolution - ability to see ﬁne detail
Types of Microscopes
•allows us to magnify cells up to 1000 times and to resolve details as small as
•Light microscopy allows us to see cells of 400- 700 um.
•If a cell is 100um will be unable to see the organelles, due the to the resolution
being unable to work, even if you can keep magnifying.
•A bright light must be focused onto the specimen by lenses in the condenser.
•The specimen must be carefully prepared to allow light to go through it.
•Phase contrast microscopy:
•Uses a light microscope with an optical component to take advantage of the
different refractive indexes of light passing through different regions of the
•Employs a light microscope and requires that samples be ﬁxed and stained
in order to reveal cellular details.
•Fluorescent dyes or probes used for staining cells are detected with the aid of a
•This is similar to light microscope except that the illuminating light is passed through
two sets of ﬁlters.
•A specialized type of ﬂuorescence microscope that builds up an image by
scanning the specimen with a laser beam.
•Rather than using light, electrons are used
•There is much greater resolution and magniﬁcation than light microscopes.
•There is a better level of resolution because the wave lengths involved are shorter
than used in light microscopy.
•Electron microscope images are not in colour
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