I think that is a specific kind of LASER that is beeing developed to study the skin angiogenesis in flaps.

I am not sure but I've seen paper where they inject contrasting dye in blood cyrculation. Atrer you could see vessels through the skeen on ears. By porabel uv illuminator and fluorecence check you could document this..  Also there are inks which after IV injections will increase the contrast of the under skin vessels.

The dorsal skinfold chamber model may meet your need. By using this model, you can easily observe the blood vessel by intravital fluorescence microscopy after iv injection of FITC .

Oregon Green 488 or CFSE also not toxic and very bright.

von Willebrand antibody works