A light reflector for use with a light source and a light detection mechanism is disclosed. The light source and the light detection mechanism are mounted on a substrate. The light reflector includes a generally hollow portion having a first end and a second end. A reflective surface is disposed upon the first end of the generally hollow portion. The second end is attached to the substrate such that the substrate and the light reflector define a substantially airtight enclosure that is of sufficient size to accommodate therein the light source and the light detection mechanism.