Described herein is a sensor for sensing reflective material. The sensor includes a housing with a transparent window and a sensor mount located in the housing and angled away from a housing wall. A radiation emitter is mounted in the sensor mount and emits radiation along an axis through the transparent window which has an amount of the reflective material located thereon. A radiation detector is mounted in the sensor mount and located adjacent the radiation emitter. The radiation detector is located to receive reflected radiation from the reflective material along another axis. The first axis is angled towards the second axis.
