Harmonic Generation Microscopy (IMAGE) Optica Caption This series of harmonic generation microscopy images shows the skin cells of a 24-year-old subject at increasing depths, ranging from the outermost layer of skin (a) to approximately 300 millionths of a meter deep (f). The magenta areas, generated from third harmonics, show skin cells and their nuclei. The green areas, generated from second harmonics, show fibers made of the protein collagen. Credit <i>Biomedical Optics Express</i> Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.