 For example, Raman microscopy of biological and medical specimens is often performed using red to near-infrared excitation (e.g., 785 nm, or 1064 nm wavelength).Due to typically low absorbances of biological samples in this spectral range, the risk of damaging the specimen as well as autofluorescence emission are reduced, and high penetration depths into tissues can be achieved.However, the intensity of Raman scattering at long wavelengths is low (owing to the ω4 dependence of Raman scattering intensity), leading to long acquisition times.