The bright-field microscope allows us to view stained or naturally pigmented samples that are highly contrasted. The source of illumination is white light. The components of the sample are visualised thanks to the differences in contrast between them and the surrounding medium.
The confocal microscope allows us to visualize images with different fluorescent labelling, therefore obtaining images of great sharpness and quality because the pictures earned are not contaminated by light emitted outside the focal plane. Thanks to this confocal characteristic, we can perform three-dimensional reconstructions from optical sections.
The variety of fluorescent proteins and multicolour probes that have been developed allows virtually any molecule to be tagged. The ability to visualise protein dynamics in vesicles, organelles, cells and tissues has provided new information about the functioning of cells in both healthy and diseased situations. This information includes the spatio-temporal dynamics of processes, such as mitosis; studies on the dynamics of ions, such as Ca+₂ and changes in the cytoskeleton.
Fluorescence is one of the most widely used physical phenomena in biological and analytical microscopy, mainly because of its high degree of sensitivity and specificity. Fluorescence microscopy allows users to determine the distribution of a single molecule, its quantity and its location within a cell.
Fluorescence microscopes used in research applications are based on a series of optical filters. The filters are usually inserted in a filter block. While the excitation filter selects the wavelengths that excite a particular fluorophore within the sample, the emission filter acts as a kind of quality control, as it only allows the wavelengths of interest emitted by the fluorophore to pass through.