Figure 4: In vivo healthy skin, 760 nm excitation wavelength. The acquisition of the images has been achieved by means of the DermaInspect equipped with the FLIM system, planned, and built by the Photonics Group of the Imperial College of London. (a) The autofluorescent signals of keratinocytes, melanin containing keratinocytes, and melanocytes appear monomorphous, and, in the grey-scale images, they cannot be distinguished from each other. (b) The FLIM image enables the identification of melanin-containing cells based on the different fluorescence decay time values (keratinocytes appear green-blue and melanin containing keratinocytes and melanocytes appear yellow-red).