High resolution ultra sounds
It is well known that as higher the ultrasound frequency is, the better the resolution and smallest superficial tissue structures visualization and measurements. To diagnose skin changes you need probes from 22 to 100 MHz, which allow you to evaluate the entire skin thickness and for epidermis and dermis sighting examination. The most optimal frequencies in this practice are 33-75 MHz.
Interferometric confocal microscopy
Technique using fringes modulation produced by the interference between a reference surface and the sample coupled to a Z scanning device (piezo). this technique has a Z resolution of a fraction of the wavelenght used over a range of hundred microns. The measurement area depends on the objective used from few he=undred of microns to the square millimeter.