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The phase-plate increases the phase
difference to half a wavelength. Destructive interference
between the two sorts of light when the image is projected
results in the specimen appearing as a dark object. |
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The Phase Contrast
Microscope
The phase contrast microscope
is widely used for examining such specimens as
biological tissues. It is a type of light microscopy
that enhances contrasts of transparent and colorless
objects by influencing the optical path of light. The
phase contrast microscope is able to show components
in a cell or bacteria, which would be very difficult
to see in an ordinary light microscope.
Altering the Light
Waves
The phase contrast microscope uses the fact that the
light passing trough a transparent part of the
specimen travels slower and, due to this is shifted
compared to the uninfluenced light. This difference
in phase is not visible to the human eye. However,
the change in phase can be increased to half a
wavelength by a transparent phase-plate in the
microscope and thereby causing a difference in
brightness. This makes the transparent object shine
out in contrast to its surroundings.
The Invisible
Can Be Seen
The phase
contrast microscope is a vital instrument in
biological and medical research. When dealing with
transparent and colorless components in a cell,
dyeing is an alternative but at the same time stops
all processes in it. The phase contrast microscope
has made it possible to study living cells, and cell
division is an example of a process that has been
examined in detail with it. The phase contrast
microscope was awarded with the Nobel Prize in
Physics, 1953.
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