A biological microscope uses transmitted light for observation. However, different observation modes have been developed to use specific light characteristics for specific samples, such as transparent specimens and samples that do not pass light.

The table below shows the features of major observation modes. Each observation mode has been developed to properly use characteristics of light such as scattering, diffraction, polarization, interference, and fluorescence.

Observation modes Features Common observation targets
Brightfield microscopy A general observation mode for biological microscopes, which features a bright field-of-view with transmitted illumination Living organisms, cells
Darkfield microscopy Uses scattered light, not direct light, to make samples shine against a dark field-of-view Microorganisms, cells
Phase contrast microscopy Uses phase (light variations) to convert a sample to brightness contrast for observation Colorless transparent samples, living cells
Polarized light microscopy Illuminates a sample with polarized light to convert it to brightness or color contrast for observation Crystals such as rocks and minerals, polymers
Differential interference contrast microscopy Uses the difference in distances that the transmitted light travels after passing through a sample to generate color or brightness contrast for 3D observation Colorless transparent samples, living cells
Modulation contrast (relief contrast) microscopy Converts the difference in heights of a sample to brightness contrast for 3D observation Cells in plastic containers
Fluorescence microscopy Stains a sample with a fluorescent compound or fluorescent protein such as GFP to observe the part that expresses fluorescence Cells and tissues dyed or labeled with a fluorescent dye, living organisms that exhibit intrinsic fluorescence
Reflected light microscopy Uses reflected light to observe samples that do not pass light Metals
Dispersion staining microscopy Immerses a sample in index oil and uses transmitted light scattered in the oil for observation Detection of asbestos
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