Luminescent sensor for an optical temperature-measuring device

Claim 1

In a fiber-optic temperature-measuring device which comprises means providing energizing radiation, a luminescent temperature-measuring transducer means, a detector means to receive radiation from the transducer means and at least one optical fiber means optically linking the means providing the energizing radiation, the transducer means and the detector means, the improvement wherein the transducer means comprises a crystalline sensor material which contains luminescent neodymium ions, at least some of these luminescent ions being so located in the crystal lattice of the sensor material that for each of said at least some luminescent ions each immediately adjacent anion substantially shows inversion symmetry in relation to that luminescent ion said crystalline sensor material being selected from the group consisting of Aa 2 AbNd x R 1-x Ha 6 , Aa 5 Nd x R 1-x Ab 2 Ha 10 , Nd 2 Sn 2 O 7 and Ba(R 0 .5-x Nd x Ta 0 .5)O 3 , where Aa and Ab are alkali metals, Nd is neodymium, R is an optically inactive rare earth metal, Ha is a halogen, Sn is tin, O is oxygen, Ba is barium, Ta is tantalum, and x designates the concentration of neodymium given as a mole fraction and is greater than zero and less than or equal to one.