Fluorescence imaging allows molecules beyond the resolution limit of the light microscope to be visualized. Fluorescence microscopy is a key technique in clinical diagnostic (for example, immunology, pathology, microbiology, cytogenetics) and research environments. Confocal fluorescence microscopy, in particular, has become an essential tool central to the study of structural and molecular dynamics in living cells. Fluorescence enables imaging techniques such as TIRF, FRET, FLIM, FLIP and FRAP. Fluorescence microscopy is also important for identifying fluorescent minerals, contaminants and impurities in materials science, geology, semiconductor inspection, and environmental protection.