Rapid in vivo measurement of the topography of human skin by active image triangulation using a digital micromirror device

Background/aims: Topometry is one of the most relevant methods for biophysical research on skin in dermatologic and cosmetic science, because it relates very closely to the perceived quality of skin. Taking silicon replicas of skin sites under investigation and measuring those imprints with mechanical or optical profilometers is still the most frequently used method. Direct measurement of the topography of human skin in vivo by active image triangulation avoids the need to make replicas and seems to be a promising alternative. Methods: The introduction of active image triangulation in conjunction with phase-shift techniques in skin topometry enables a fast and non-invasive measurement of the skin surface in vivo. The main attribute of the proposed system is the projection of a regular sinusoidal intensity pattern with a sophisticated digital projection device onto the surface of skin under a certain angle of incidence. The height information of the structured surface is coded in the distorted intensity pattern, which is recorded by an appropriate video technique. Results: Successful in vivo measurements of selected body sites and measurements on scar, nevus, wound and wrinkles are presented in this paper. Furthermore, irritation of skin, influence of hydration of skin, and differences between youthful and elderly skin can be detected in the measurement results of the new optical system. Conclusions: For measuring the topog raphy of human skin, active image triangulation is appropriate both for macrotopometry (nevus, scar, wound) and for microtopometry (casts, selected body sites). This new non-contact technique allows dynamic measurements of alterations in skin topography as a consequence of certain treatments (e.g., application of ingredient, hydration of skin) without removal of corneocytes or scales. Optical three-dimensional (3D) topometry using active image triangulation appears to offer a significant improvement in speed and flexibility, providing a fast and accurate analysis of skin surface topography.