Glasses for Fiber-Optic Sensors.

Abstract : The work this year has centered on the development of cladding glasses for pressure insensitive fibers. The accomplishments have been: (a) the synthesis of eight glasses of varying composition for the minimization of linear thermal expansion coefficient; (b) the measurement of elastic moduli and thermal expansion coefficients of the aforementioned glasses; (c) the development of glasses with linear thermal expansion coefficients comparable to Pyrex; (d) the fabrication of a cladding preform from one of the NBS produced glasses which was selected for optimum values of bulk modulus and linear thermal expansion coefficient so as to produce a pressure insensitive fiber; (e) the provision of bulk specimens and thin rods to EOTEK Corporation per instructions from the contract monitor; and (f) the filing of an invention disclosure with the NBS patent attorney to ascertain whether the glass compositions formulated at NBS merit a patent. A series of beryllium-free glasses have been formulated that exhibit a high Young's modulus (E), a high bulk modulus (K), and a wide range of expansivities. Several of the glasses exhibit unusually small linear thermal expansion coefficients (alpha) at room temperature. The glasses were formulated with the view of not including Be0 as a constituent because of its potential toxicity.