ABSTRACT
Noninvasive in vivo imaging of the upper skin layers has applications in dermatology and cosmetology. Here the importance lies in the ability to investigate the skin structure without taking skin biopsies. However, it is difficult to image skin optically due to the large extinction by scattering and the relatively short scattering lengths. In selecting an imaging technique, one has to make a trade-off between penetration depth and spatial resolution. Available techniques range (in order of decreasing penetration depth and increasing axial resolution) from magnetic resonance imaging, ultrasonography, photoacoustic imaging, optical coherence tomography, and optical coherence microscopy to confocal and multi-photon microscopy. The microscopic techniques have about 200mm penetration depth and up to one-micrometer resolution and are therefore suitable for imaging the upper layers of the skin at the cellular level.
