Fifth-harmonic and five-photon excitation fluorescence multiphoton microscopy

We report the application of fifth-harmonic and five-photon excitation fluorescence multiphoton microscopy. This novel, to our knowledge, label-free imaging modality has been characterized with spectral and power dependence measurements. The advantages of fifth-harmonic and five-photon excitation fluorescence imaging are higher resolution and use of longer wavelength excitation sources, which may allow deeper penetration depth while still exciting near-UV to blue fluorophores. This imaging modality may find interesting applications in biological research, materials characterization, geologic studies, and semiconductor manufacturing.