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Updated: Dec 13, 2025

Characterization of Biological Absorption Spectra Spanning the Visible to the Short-Wave Infrared
Published on: January 10, 2025
Practical two-photon-absorption cross sections and spectra of eosin and hematoxylin
Jacopo Parravicini1,2, Alessandra Tomaselli3, Elton Hasani3,4
1Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Milan, Italy.
Abstract:
We experimentally investigate the two-photon absorption cross sections and spectra of eosin and hematoxylin for applications in nonlinear microscopy. The experiments are carried out on pure samples of the two dyes in DI-water solvent with different concentrations, in the typical range employed in standard staining procedures. Nonlinear fluorescence is excited by a line-shaped beam emitted by a Ti:Sapphire mode-locked laser in the wavelength range from 740 to 880 nm and is detected through a microscope setup. The two-photon absorption spectral response is systematically analyzed and discussed. Finally, the staining is applied on biological tissue samples, which are imaged by two-photon microscopy. Our results show that the employed dyes are fully suitable for applications in nonlinear imaging.
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