The most commonly used microscopy imaging technique is brightfield microscopy, where light is either passed through or reflected off a specimen. However,
there are also techniques known as darkfield microscopy, phase contrast microscopy, differential interference contrast (DIC) microscopy, fluorescence microscopy,
and polarizing microscopy. Each of these methods is best suited for different uses. Research class microscopes allow these techniques to be utilized merely
by switching attachments.
| Brightfield microscopy |
Observation is made by viewing the light passed through or reflected off a specimen.
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Main uses:
Viewing stained specimens
Pathological exams
Blood tests
Wafer inspections
Liquid crystal board inspections |
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HE stained stomach wall at
10X |
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Darkfield microscopy
A special condenser lens is used to illuminate the specimen diagonally, then observe light scattering off it. The field of view is darker than brightfield
microscopy because illumination light does not enter the objective lens.
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Main uses:
Microbiological imaging
Blood tests
Detecting microscopic scratches or irregularities |
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Abdominal wall muscle at
10X |
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Phase contrast microscopy
The optical phenomena of diffraction and interference are used to add light/dark contrast to a transparent specimen for imaging. There is no need to stain
the specimen as in brightfield microscopy, so live specimens can be used.
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Main uses:
Imaging cultured cells
Imaging blood or living cells |
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Abdominal wall muscle at
10X |
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Differential interference contrast (DIC) microscopy
Differential interference contrast microscopy transforms minute differences in refraction indexes of light passing through an unstained specimen, or optical
path differences from the specimen surface shape, into a monochromatic shadow-cast image enabling observation. As with phase contrast microscopy, DIC microscopy
may be used with living specimens. However, it is better suited to thicker specimens.
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Main uses:
Imaging fibrous structure of nerve or muscle
Imaging mitotic spindles
Imaging cellular nucleic structures or other thick unstained specimens
External examination of IC wafer surfaces or polished surfaces of magnetic heads
Observation of crystal growth process
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Abdominal wall muscle at
10X |
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Fluorescence microscopy
Specimen is excited with a specific wavelength of light, then fluorescent emanations are observed.
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Main uses:
Imaging and quantification on calcium ion dynamics in living cells
Assaying antigens in antigen/antibody reactions
Imaging and quantification of intracellular DNA and RNA
Analysis of chromosomal abnormalities
Detection of resists remaining in semiconductor fabrication process
Detection and assaying of foreign particles
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Bovine neck nerve cell at
40X |
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Polarizing microscopy
This technique uses the phenomenon of polarization to add contrast and color to specimen images.
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Main uses:
Analysis of optical properties of rocks, ores, polymers, and experimental materials
Detection of defects in the liquid crystal display element fabrication process
Detection of defects in separation membranes
Imaging magneto-optic disks and bubble memory
Polarization analysis of fine structures within living organisms and cytoskeletons
Gout testing
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