title: Precision thermal expansion measurements on low expansion optical materials.
abstract: Recent critical applications for ultralow expansion materials have required thermal expansion measurements with very high precision and accuracy. A Fizeau interferometer employing a helium-neon laser has given a precision of +/-0.1 x 10(-6) cm/cm. A second, more rapid method consists of a rod type vitreous silica dilatometer. A stirred water bath is used for specimen temperature control and a high output, linear variable differential transformer serves as the extensometer. Precision of this method is +/-0.5 x 10(-6) cm/cm. Calibration procedures and results for several low expansion materials are discussed.
authors.forename: W A
authors.initials: WA
authors.lastname: Plummer
authors.forename: H E
authors.initials: HE
authors.lastname: Hagy