Book excerpt: For a host of reasons, nonlinear optical spectroscopy is a valuable tool for biochemical applications where minimally invasive diagnostics is desired. Biochemical Applications of Nonlinear Optical Spectroscopy presents the latest technological advances and offers a perspective on future directions in this important field. Written by an international panel of experts, this volume begins with a comparison of nonlinear optical spectroscopy and x-ray crystallography. The text examines the use of multiphoton fluorescence to study chemical phenomena in the skin, the use of nonlinear optics to enhance traditional optical spectroscopy, and the multimodal approach, which incorporates several spectroscopic techniques in one instrument. Later chapters explore Raman microscopy, third-harmonic generation microscopy, and non-linear Raman microspectroscopy. The text explores the promise of beam shaping and the use of broadband laser pulse generated through continuum generation and an optical pulse shaper. Lastly, the book discusses the effects of spatial beam shaping on the generated nonlinear Raman signals in a tightly focused geometry and provides insight into the extension of nonlinear optical spectroscopy to the nanoscale through the use of plasmonic tip-enhanced arrangement. With novel experimental approaches to this technology expanding day-by-day, the book’s balanced coverage from a wide range of international contributors not only elucidates important achievements, but also outlines future directions in this dynamic and promising field.