Patent ID: 8314388

Claim:
An apparatus for sensing a layer of material, with a first surface and a second surface wherein the second surface is coated on a reflective laminant substrate, that comprises: a housing having an operative surface; a radiation source, disposed within the housing, that directs a beam of incident radiation away from the operative surface and into the layer of material through the first surface; a radiation receiver, disposed within the housing, that detects at least a portion of a reflected beam that propagates through the layer of material which is transmissive to radiation; means for reflecting radiation through the layer of material a plurality of times before being detected by the radiation receiver, wherein the means for reflecting radiation comprises a reflective surface that is secured to the operative surface and wherein the layer of material is positioned so that radiation that is transmitted through the layer of material is reflected through the layer of material by the reflective laminant substrate and the reflective surface that face each other with the layer of material being situated in between; a diffuser element attached to the reflective surface; and clear protective layer on the diffuser element.