Patent ID: 7189960

Claim:
An optical moisture sensor, comprising: a) a solid, elongated body of transparent material having an axis, said body having formed therein first and second axially spaced cavities, each of said cavities being tapered in a direction toward the other; b) a light-emitting device positioned in said first cavity; c) a light-sensing device positioned in said second cavity; d) the walls of said first cavity being so curved that divergent light rays emanating from said light-emitting device are refracted at said first cavity walls into parallelism with each other in said material in a direction toward the surface of said body at an angle to said surface; e) the walls of said second cavity being so curved that parallel light rays impinging thereon from a direction toward said axis are refracted at said second cavity walls into convergence upon said light-sensing device; f) said angle being such that parallel light rays impinging upon said surface are substantially reflected as parallel rays toward said second cavity walls when said surface is exposed to a first fluid, and are substantially refracted outwardly of said body when said surface is exposed to a second fluid.