A substance detection apparatus and method including a light source to emit light to a planar transparent member having a proximal first face and a distal second face opposite the first face, the light from the light source first striking the first face of the planar transparent member. The substance detection apparatus and method including an image capture lens, a polarization filter, an image sensor, and a substance detection processor. The light emitted from the light source is reflected at the substance present on the second face of the planar transparent member, and the image sensor receives light reflected from the substance, via the image capture lens and the polarization filter, to capture an image of the substance present on the second face of the planar transparent member.