A probe head for a diagnostic instrument using Raman spectroscopy for tissue measurements, the probe head comprising； a transmission optical fiber, a plurality of collection optical fibers, and a lens to transmit light from the transmission optical fiber to a test site, wherein the ends of the collection optical fibers are beveled or angled. The beveled surfaces can face towards or away from the end of the transmission fiber. Optical elements are used to gather and filter light scattered from tissue, and analysed to identify abnormal tissue.
