Fluorescence microscopy

Fluorescence microscopy uses fluorescent molecules and selective illumination to visualize structures or molecules in a specimen. Emitted light distinguishes labeled targets from the surrounding background.

Fluorescence: Fluorescence is light emission by a substance after it absorbs electromagnetic radiation, usually at a shorter wavelength. Fluorescent labels emit light after excitation, providing the signal this microscopy detects.
Fluorescent protein: A fluorescent protein is a protein that emits light after excitation, often used as a genetically encoded label. Fluorescent proteins let cells produce labels attached to selected proteins or compartments.
Wide-field fluorescence microscopy: Wide-field fluorescence microscopy illuminates and detects fluorescence across a broad specimen area at once. It is a straightforward approach for thin specimens and rapid imaging.
Bright-field microscopy: Bright-field microscopy forms an image from transmitted light, with specimen regions appearing darker than the illuminated background. It contrasts with fluorescence imaging, which detects emitted light from labeled targets.
Fluorophore: A fluorophore is a molecule or molecular group that absorbs light and emits fluorescence. Fluorophores attach or bind to targets so those structures produce detectable light.
Immunofluorescence: Immunofluorescence uses fluorescently labeled antibodies to detect specific antigens in cells or tissues. It supplies target specificity through antibody binding rather than genetic labeling.
Confocal microscopy: Confocal microscopy rejects out-of-focus light using a spatial pinhole and scans focused illumination across a specimen. Its optical sectioning improves contrast in thicker fluorescent specimens.
Phase-contrast microscopy: Phase-contrast microscopy converts phase shifts in transmitted light into intensity differences in an image. It visualizes transparent specimens without requiring fluorescent labels.
Stokes shift: The Stokes shift is the difference between the wavelengths of light absorbed and emitted by a fluorescent substance. The wavelength shift lets filters separate emitted signal from the illumination used for excitation.
Fluorescence in situ hybridization: Fluorescence in situ hybridization uses fluorescent nucleic-acid probes to locate specific DNA or RNA sequences in cells or tissues. It applies fluorescent labeling to map selected nucleic-acid sequences in place.

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