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Fringes deformation |
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OBSERVING WITHOUT ALTERING
Measuring colour, sebum secretion, softness of touch, the effects of ageing or sun, implies having non invasive (i.e. painless) methods that in no way harm the skin's integrity, and are both producible and reliable.
Dimensions, physical nature of its components and the way they are organised governed the macroscopic properties of Material. In the case of skin, we are dealing with something extremely complex. As far as thickness is concerned, the epidermis is ten times thinner than the dermis, and the horny layer is ten times thinner than the epidermis in most areas of the body, while the hypodermis can be several times thicker than the dermis.
Apart from these geometrical considerations, the skin is made up of cells, fibres, and liquids which all have very different properties. Furthermore, the way they are organised and their relative quantity differ according to the various areas and layers.
In order to analyse such a complex set of parameters, biophysicists concieved a whole range of specialised tools. Here, we will only be describing those most often used to analyse and observe healthy skin, and to assess the efficiency of cosmetics.
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