Confocal Microscopy

Confocal microscopy is a type of fluorescence microscopy which uses a laser to excite fluorescence from fluorophores used to label different subsets of a specimen. Fluorescence microscopes are used for imaging cells and tissues that have been fluorescently tagged. What separates confocal microscopy from conventional epi-fluorescence microscopy is its increased resolution when imaging thick specimens, elimination of out-of-focus glare due to spatial filtering, and reduction of light-induced damage to the sample, known as phototoxicity.

Instead of using an incoherent tungsten or mercury lamp source like conventional microscopes, confocal microscopes use a laser to illuminate the sample. The system then collects images at planes at various depths in the sample, known as optical sections, by scanning the laser through different focus positions. Optical sections enable live specimens to be imaged because the sample doesn’t need to be physically sectioned off. The illumination of smaller sections also helps specimens to remain viable longer by significantly reducing the effects of phototoxicity. The amount of light that conventional techniques use for illumination makes it difficult to ensure the vitality of the specimen imaged, which is crucial when capturing biological events.