Patent ID: 8271198

Claim:
A self-contained optical moisture sensor unit comprising: a housing; a substantially planar circuit board disposed substantially horizontally in the housing; at least one light emitter and at least one light detector mounted on the circuit board; a lens having a predetermined geometric shape and being light transmissive, sealingly mounted on the housing, the lens comprising: an inner sensing surface and an outer sensing surface, the outer sensing surface being substantially continuously concave in shape relative to the circuit board, and the inner sensing surface also being substantially continuously concave relative to the circuit board, and at a predetermined distance above the at least one light emitter and at least one light detector wherein the moisture sensor has a radial distance Rd which is from 68% to 80% of the radius of the outer sensing surface of the lens Rs; at least one control circuit to control the at least one light emitter and at least one light detector; and software to analyze at least the data received by the at least one light detector.