Photobleaching
Definition
The irreversible photochemical destruction of a fluorophore by repeated excitation. Limits the observation time for low-copy forensic fluorescence samples. Mitigated by antifade mounting media and minimised exposure.
Related terms
- Autofluorescence
- Native fluorescence of endogenous biological molecules (collagen, elastin, NADH, flavins) that produces background signal in fluorescence microscopy, potentially mimicking specific probe signals....
- Birefringence
- The difference between the highest and lowest refractive indices of an anisotropic mineral, seen as a characteristic interference colour between crossed polars....
- Conoscopic Illumination
- A convergent polarised beam mode in which a range of angles is passed through the specimen simultaneously, producing an interference figure (optical...
- Crossed Nicols
- The configuration in which the polariser (below the condenser) and the analyser (above the objective) are oriented at 90 degrees to each...
- DAPI
- 4',6-diamidino-2-phenylindole; a fluorescent dye that binds double-stranded DNA and emits blue (~460 nm) under UV excitation (~360 nm). Standard nuclear counterstain; used...
- Dichroic Mirror
- A spectrally selective beam splitter that reflects shorter (excitation) wavelengths at 45 degrees and transmits longer (emission) wavelengths, forming the core element...
- Epi-Fluorescence Illumination
- Fluorescence excitation through the objective lens from above the specimen, with the same objective collecting the emission. A dichroic mirror directs excitation...
- Extinction Angle
- The angle, measured in degrees on the rotating stage of a petrographic microscope, between a crystallographic reference direction (cleavage trace or crystal...
- Michel-Lévy Chart
- A birefringence-thickness diagram correlating retardation values with the interference colour seen at that retardation under white-light crossed polars. Standard reference for identifying...
- Retardation
- The path difference (in nm) introduced between the fast and slow ray components as they traverse an anisotropic specimen of given thickness...
- Stokes Shift
- The wavelength difference between the excitation peak and the emission peak of a fluorophore. A positive Stokes shift (emission at longer wavelength...
Explained in
- Polarising and Fluorescence MicroscopesThe irreversible photochemical destruction of a fluorophore by repeated excitation. Limits the observation time for low-copy forensic fluorescence samples. Mit...