Cosmetic Assessment of Human Hair by Confocal Microscopy

Confocal microscopy has emerged as a significant advancement over scanning electron microscopy (SEM) for the cosmetic assessment of human hair, due to its ability to observe hair in its natural state with minimal sample preparation and less damage. This technique is used to evaluate the effectiveness of cleansing shampoos, the uniformity of polymer layering, and the impact on hair surface optical properties such as opacity, transparency, and brilliancy. Additionally, the fluorescence channel of confocal microscopy, with the aid of fluorescent probes like rhodamine, allows for the visualization of the hair's internal structure, including the penetration pathways and the arrangement of cortical cells and the medulla. The three-dimensional rendering of hair provided by this technology offers a comprehensive view of the interaction between different hair components, making confocal microscopy an essential tool for cosmetic hair analysis.