Special Section Guest Editorial: Multiphoton Microscopy: Technical Innovations, Biological Applications, and Clinical Diagnostics

When Maria Goeppert-Mayer made theoretical prediction of the two-photon absorption process over eighty years ago, little could be foreseen of the revolutionary breakthroughs her prediction would contribute to optical microscopy in biological sciences. However, in the past few decades, one of the most exciting developments in optical microscopy has been the extension of nonlinear optical phenomena into the realm of biological imaging.