An optical device for illuminating the vasculature of a mammal using ultraviolet, visible, and/or infrared light is described. The optical device includes an optical fiber encased in a biocompatible sheath, and is dimensioned to lie within an intravascular catheter. When placed within a vascular space and coupled with a suitable light source the optical device illuminates the vascular space and its contents. The faces of the optical fiber are configured to optimize the capture of ultraviolet, visible, and/or infrared light from a light source without the use of active optics.
