A new approach for the measurement of a refractive index is presented, following the introduction of a novel feature based on the selection of a large number of angles of incidence along a direction of symmetry at the prism-ambient interface, without moving the incident beam. This gives rise to very high sensitivities over a refractive index range determined by the divergence of this beam.
The new design for the prism based refractometer sensor presented here is characterized by its high sensitivity over a wide range of refractive indices of the ambient. The refractometer is more robust and user friendly than other such refractometers reported in literature.
The newly designed prism based fiber optical refractometer sensor has been used to determine adulteration in petrol. A procedure for identification of the adulterant and determination of its concentration in a sample of petrol has been reported. Substances like kerosene, diesel, a mixture of these two or of aviation gasoline and kerosene have been used as adulterants.