Multiphoton Confocal Microscopes are advanced fluorescence imaging systems that use near-infrared femtosecond pulsed lasers to excite fluorophores through the simultaneous absorption of two or more photons. This nonlinear excitation occurs only at the focal point of the laser, eliminating the need for a pinhole to block out-of-focus light and providing intrinsic optical sectioning. Because near-infrared light penetrates deeper into tissues and causes less scattering and photodamage than visible light, these microscopes are especially suited for imaging thick, living specimens and even intact tissues in vivo.