A couple of skin confocal references:
Corcuff and Leveque, "In vivo vision of the human skin with the tandem
scanning microscope," Dermatology 186, 50 (1993)
Corcuff, Bertrand, and Leveque,"Morphometry of human epidermis in vivo
by real-time confocal microscopy," Arch. Dermatol. Res. 285, 475 (1993).
If I remember correctly, they were working in reflection and could get
down to a depth of a couple hundred microns.
David Aziz
Univ. of Arizona