Modernized state primary standards of the units of thermal quantities

Extending the Temperature Range of the National Primary Standard for the Unit of the Thermal Linear Expansion Coefficient

“…The measurement method and metrological characteristics of the fi rst two dilatometers included in the standard have been described in detail elsewhere [1][2][3]. After approval of the standard GET 24-2007 for temperatures of 90-1800 K, the accuracy with which the CLTE could be measured was increased by a factor of 2-3 to 0.5·10 -9 K -1 and the lower limit of the measureable values was reduced by a factor of fi ve [4,5]. Interference measurements based on a Fizeau interferometer were used in all the standards systems.…”

Interference dilatometers for measuring the thermal coefficient of linear expansion of thermally stable optical materials

“…In particular, this is caused by the different configurations of the samples to be measured by the commercial and standard dilatometers that are used in an SPS and are based on noncontact interference measurements of the variation of the sample's length. 1 It is therefore expedient to use interference dilatometers to solve the problems of monitoring thermally stable optical materials. In this case, facilities for converting the measurement units-the TCLE measures-can be created directly, using an SPS to certify them.…”