1. To characterize human lung lesions by nonlinear microscopy using ex vivo tissues. In particular, to investigate collagen content and ultrastructure with SHG (second harmonic generation) microscopy, to characterize cell and nuclear morphology and lipid vesicle content with THG (third harmonic generation) and CARS (coherent anti-Stokes Raman scattering) microscopy and to conduct spectroscopic and lifetime characterization of MPF (multiphoton fluorescence) signals in cancerous, benign, and normal tissues.