Optical metrology to determine thermal expansions of ultra stable materials used in space applications

We present the status of our measurement system to investigate the coefficient of thermal expansion (CTE) of ultra stable materials. Low CTE materials are important for stable structures in space applications to enable precise measurements. Various material samples were determined with our heterodyne interferometer which offers a noise level below 2 pm/√Hz at frequencies above 0.1 Hz. Our setup is designed such that we are able to measure e.g. CFRP (Carbon Fiber Reinforced Plastic) samples with CTEs of 10^-8 K^-1. Glass ceramics like Zerodur and Clearceram are measured to validate our facility. A measurement of a Clearceram-Z HS sample is shown in this article.