An Optical Low Coherence Reflectometer with a spatial resolution of 1.5 micrometers (FWHM) in biological tissue has been developed. This high resolution is obtained using the fluorescence generated by an Ar-laser pumped Ti-Sapphire crystal. Measurements have been performed on freshly excised pig eyes and bovine mesenteric arterial walls, as examples of transparent and diffusive biological tissues, respectively. The improved spatial resolution is used to determine more precisely optical distances and to resolve details of the intima structure.