two-photon excitation (2PE)

Two-photon excitation refers to the excitation of a system by two photons arriving simultaneously and via a virtual energy level, commonly used in multiphoton microscopy. The two-photon excitation wavelength tends to be roughly twice the usual one-photon excitation wavelength.

See also: multiphoton excitation, one-photon excitation, three-photon excitation, multiphoton microscopy

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Multiphoton Microscopy

Mode-locked pulsed lasers are used for deep tissue imaging and optical sectioning.