State-of-the-art optical materials production, in particular fabrication of unique Sitall materials intended for generation of Mirrors for modern large-size and super-large astronomical telescopes is impossible to do without testing of one of the main physical parameter of material – Coefficient of Thermal Linear Expansion (CTE).

Having created the high-precision testing equipment for CTE checking with purpose to solve its own production tasks, LZOS, JSC offers this equipment to Customers that are needful to have CTE measurements with more high accuracy than standard testing tools can ensure.

Theoretical analysis shows that testing accuracy of low expansion materials is defined first of all by a testing system accuracy of an example linear elongation. Therefore one of the most accurate testing methods is interference one was under lied for creation of the dilatometric installation. At the same time an interference pattern recording and processing is conducted computer controlled in ‘real time’ mode.

Dilatometric Analysis Installation is composed of the interferometric measuring system, the vacuum thermo cryostat where a sample under testing is located in and the monitor and control system on PC base.

The independent metrological researching studies of Dilatometric Installation conducted by experts of Mendeleev Metrology Institute of RF have testified that the tolerance of CTE absolute measurement within 20 degrees range of temperatures does not exceed 2 x 10^-8 K^-1. And when measurement is conducted by a differential method (for example in case when CTE homogeneity within a blank of material is needed to be tested) the tolerance of measurement equals to 0.8 x 10^-8 K^-1. Tolerances could be lower at some conditions of testing.