Winfried Denk, James P Strickler, Watt W Webb: Two-photon laser microscopy. Cornell Research Foundation, Jones Tullar & Cooper, July 23, 1991: US05034613 (287 worldwide citation)

A laser scanning microscope produces molecular excitation in a target material by simultaneous absorption of two photons to thereby provide intrinsic three-dimensional resolution. Fluorophores having single photon absorption in the short (ultraviolet or visible) wavelength range are excited by a str ...