Optical probe for measuring the level of a liquid in a tank

An optical probe suitable for measuring the level of a liquid in a tank, comprising:

• a transparent and refracting optical waveguide suitable for receiving an injection of a collimated light beam at a predetermined angle of incidence, said optical waveguide being configured to internally reflect the collimated light beam according to a total reflection regime in any part of the optical waveguide located in a gaseous medium and to refract the collimated light beam according to a refraction regime in any part of the optical waveguide immersed in a liquid medium, said optical waveguide being capable of switching from the total reflection regime to the refraction regime at the interface between the gaseous medium and the liquid medium;
• mirrors arranged around said optical waveguide and suitable for reversing the path of a collimated light beam refracted by the optical waveguide at the interface between the gaseous medium and the liquid medium;
• and
• a telemetry tool suitable for injecting the light beam in the form of a light pulse into said optical waveguide and for receiving in return the collimated and reversed light beam making it possible to measure the length of the optical path travelled by the light beam and to deduce therefrom the level of the liquid in the tank.