In two-photon excitation microscopy an infrared laser beam is focused through an objective lens.

These benefits for imaging in scattering tissues were only recognized several years after the invention of two-photon excitation microscopy.

Two-photon excitation microscopy can study living neuronal networks and the communicatory events among neurons(Potter 2012).

Synthetic analogs of glutamic acid that can be activated by ultraviolet light and two-photon excitation microscopy have also been described.

It can be used as an imaging technique in confocal microscopy, two-photon excitation microscopy, and multiphoton tomography.

Confocal laser scanning microscopy and Two-photon excitation microscopy make use of lasers to obtain blur-free images of thick specimens at various depths.

Typically (but not always) two-photon excitation microscopy is used in a 4Pi microscope in combination with an emission pinhole to lower these side lobes to a tolerable level.

Commonly, FCS is employed in the context of optical microscopy, in particular Confocal microscopy or two-photon excitation microscopy.

Two-photon excitation microscopy is a fluorescence imaging technique that allows imaging of living tissue up to a very high depth, that is up to about one millimeter.

Two-photon excitation microscopy : Although they use a related technology (both are laser scanning microscopes), multiphoton fluorescence microscopes are not strictly confocal microscopes.

Two-photon excitation microscopy has shown that microstimulation activates neurons sparsely around the electrode even at low currents (as low as 10 μA) up to distances as far as four millimeters away.

This allows for higher resolution microscopy, because the sample absorbs energy only in the region where two beams of different colors overlap significantly, which can be made much smaller than the excitation volume of a single beam (see two-photon excitation microscopy).