Measurement Setup to Determine Thermal Expansions from 100 K to 300 K of Ultra Stable Materials Used in Space Applications

In this article we present the status of our new setup to determine coefficients of thermal expansions (CTE) of ultra stable materials at temperatures from 300K down to 100 K. Such low CTE materials are important for dimensionally stable structures in space and terrestrial applications e.g. To enable precise measurements. This setup is an advancement of a measurement facility for CTE determination at room temperature with demonstrated measurements of CTE values down to 10ppb/K - 1. Due to the high temperature differences of the new setup, the mechanical and thermal setup is very important. The mechanical transfer function between interferometer and the device under test (DUT) has to be high and the thermal transfer function has to be very low to achieve the required accuracy. An overview of the new setup and its subsystems is given in this article with a measurement of the sensitivity of the interferometer.