OPTICAL IMPEDANCE MODULATION FOR FUEL QUANTITY MEASUREMENT

Optical impedance fluid level sensor that eliminates electricity for measuring fuel quantity in fuel tanks, as well as system and method using the sensor. The optical impedance sensor comprises two optical fibers spaced apart inside a meniscus tube, one to transmit light along its length and the other to receive light along its length. The meniscus tube minimizes the sloshing of fuel level. The fuel level in the tank modulates the optical impedance between the two optical fibers, resulting in changes in the total light received by an optical detector. Depending on fuel tank height, the optical impedance sensor may comprise different embodiments in which the detection apparatus shapes the light to be unidirectional, with light emitted and collected only on one side of the fibers, or omnidirectional, comprising all directions around the optical fibers.