They also demonstrated that the probe could acquire separate coherent anti-stokes Raman scattering, second harmonic generation and two - photon
excited autofluorescence images of healthy human skin tissue samples with a resolution of 2048 by 2048 pixels for a scanned area of 300 by 300 microns.
FRET sensors face challenges of photobleaching,
autofluorescence, and, in the case of
exciting cyan - excitable donors, phototoxicity.