A system for human age estimation based upon in vivo skin imaging includes a harmonic generation microscopy (HGM) device and an analysis device. The HGM device is configured for observing human skin and forming sectioned images of the human skin of second harmonic generation (SHG), third harmonic generation (THG), and combination of the SHG and the THG of an excitation light scanning the human skin. The analysis device is in communication with the HGM device and configured for processing the sectioned images to reveal relationships between the morphological features of the human skin and chronological age of a human being having the human skin.
