Optical fiber-based liquid level sensor

A liquid level sensor based on etched D-shaped silica optical fibers is presented. The optical transmission of the sensor depends on the liquid level. The sensor can be realized as a continuous level sensor with a high resolution and requires only one fiber and one optical source and detector. We have demonstrated a sensor with a resolution of similar to 1 mm. The sensor works for liquids with refractive indices greater than similar to 1.45. We show that the sensor response is the same for increasing and decreasing liquid levels. (c) 2007 Society of Photo-Optical Instrumentation Engineers.