Microscopy imaging techniques

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.

HE stained stomach wall at 10X

Main uses:

Viewing stained specimens
Pathological exams
Blood tests
Wafer inspections
Liquid crystal board inspections

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.

Abdominal wall muscle at 10X

Main uses:

Microbiological imaging
Blood tests
Detecting microscopic scratches or irregularities

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.

Abdominal wall muscle at 10X

Main uses:

Imaging cultured cells
Imaging blood or living cells

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.

Abdominal wall muscle at 10X

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

Fluorescence microscopy

Specimen is excited with a specific wavelength of light, then fluorescent emanations are observed.

Bovine neck nerve cell at 40X

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

Polarizing microscopy

This technique uses the phenomenon of polarization to add contrast and color to specimen images.

Polypropylene at 10X

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