Patent ID: 7385215

Claim:
A sensor for sensing the presence of media in contact with the sensor, comprising: a light source emitting an optical signal; a light sensitive receiver positioned to detect a reflection of said optical signal, said light sensitive receiver generating a reflection signal corresponding to an index of refraction of said media; a reflective/refractive interface positioned between said light source and said media; and a processing circuit coupled to said light sensitive receiver, said processing circuit configured to receive said reflection signal and compare said reflection signal with a predetermined threshold value; wherein if said received reflection signal meets or exceeds said threshold value, a determination is made that a first media is in contact with said reflective/refractive interface, and wherein if said received reflection signal is less than said threshold value, a determination is made that said first media is not in contact with said reflective/refractive interface; and wherein said sensor is incorporated in a supercavitational vessel to sense a distance between said supercavitational vessel and a cavity wall formed by operation of said supercavitational vessel.