SIMULTANEOUS HYDROSTATIC-PRESSURE AND TEMPERATURE-MEASUREMENT EMPLOYING AN LP(01)-LP(11) FIBEROPTIC POLARIZATION-SENSITIVE INTERMODAL INTERFEROMETER

A fiber-optic LP01-LP11 polarization-sensitive intermodal interferomet er is proposed to simultaneously measure hydrostatic pressure and temp erature using the same sensing element. In analogy to the case of stra in sensing it was found that the experimental parameters T(p) and T(T) describing the 2pi phase shifts in the interferogram are significantl y different for the X- and Y-polarizations of two polarization modes. This represents a fundamental phenomenon which can be put to use for s imultaneous two-parameter sensing. The results obtained are found to b e in agreement with a recently developed Muller-Stokes formalism descr ibing polarization effects in the case of two-mode interference by mea ns of spatial Stokes parameters. Initial calibration of the two-parame ter simultaneous pressure-and-temperature sensor has been performed up to 100 MPa using a primary pressure standard (deadweight tester Harwo od DWT-35).