In coherent Raman scattering microscopy, the sample is examined through the Raman-active modes. Although many molecular modes display a nonzero Raman cross-section, some modes are intrinsically weak and are better viewed through their dipole-allowed (IR-active) transition. A more complete spectroscopic assessment of the sample would thus include a mechanism to prove both Raman and IR-active modes. In this contribution, we combine coherent Raman microscopy with second- and third-order sum-frequency generation microscopy, providing sensitivity to all optically accessible vibrational modes. All techniques can be carried out on the same laser-scanning imaging platform, generating images at fast acquisition rates and with high spatial resolution. We show examples where the combination of these techniques reveal new information about the tissue.
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