Multi-photon excitation microscopy and confocal microscopy imaging of in vivo human skin: A comparison

We compare here multi-photon excitation microscopy and tandem scanning refl ected light confocal microscopy for the microscopic observation of human sk in in vivo. Multi-photon excitation is induced by a 80-MHz pulse train of f emtosecond laser pulses at 780 nm wavelength. This nonlinear microscopic te chnique is inherently suitable for tissue fluorescence imaging because of i ts deeper penetration depth and lower specimen photodamage. This technique has noninvasively obtained tissue structural information in human epidermis and dermis. Alternatively, tandem scanning confocal light microscopy based on a white light: source can provide video-rate image acquisition with hig h resolution and high contrast. Reflected light confocal methods have been used to obtain images from the skin surface to the epidermal-dermal junctio n. The relative merits of these two techniques can be identified by compari ng three-dimensionally resolved images obtained from the forearm skin of th e same volunteer.