Abstract:
A triaxial constructed needle probe for reliable differentiation of multiphase media, comprises a probe body having a central light conductor having a metallic surface and a distal end of which is to be inserted in the medium, a first electrically insulating sheath disposed around the optical fiber, a hollow cylindrical shield electrode arranged around the first insulating sheath, a second electrically insulating sheath arranged around the shield electrode, and a hollow cylindrical reference electrode arranged around the second insulating sheath, as well as a measuring circuit for measuring the optical refractive index and electrical conductivity of the medium.