Two-photon UV fluorescence excitation of the amino acids by a frequency doubled femtosecond optical parametric oscillator

In this study, we have demonstrated the use of a frequency-doubled femtosecond optical parametric oscillator in generating two-photon excitation that is equivalent to ultraviolet (UV) light with wavelength less than 300 nm. This capability allows observation of some amino acids and enables excitation that is only possible with wavelength in UVB range (290 nm-320 nm).