A medical device comprising an instrument head integral to the medical device having a distal portion, a light source internal to the instrument head coupled to a first channel, a first polarizing filter positioned within the first channel of the instrument head, a second polarizing filter positioned within the second channel for receiving reflected light from the light source, the reflected light received through a sensor axially aligned with the second channel is disclosed herein. The second channel may comprise a distal opening. The second channel may be configured to restrict light from entering the second channel other than by the distal opening. The first polarizing filter may be configured to polarize light from the light source.
