Structural materials with extremely low coecient of thermal expansion (CTE) are crucial to enable ultimate
accuracy in terrestrial as well as in space-based optical metrology due to minimized temperature dependency.
Typical materials, in particular in the context of space-based instrumentation are carbon-ber reinforced plastics
(CFRP), C/SiC, and glass ceramics, e.g. Zerodur, ULE or Clearceram. To determine the CTE of various samples
with high accuracy we utilize a highly symmetric heterodyne interferometer with a noise level below 2 pm√Hz at frequencies above 0.1 Hz. A sample tube made out of the material under investigation is vertically mounted in
an ultra-stable support made of Zerodur. Measurement and reference mirrors of the interferometer are supported
inside the tube using thermally compensated mounts made of Invar36. For determination of the CTE, a sinusoidal
temperature variation is radiatively applied to the tube. One of the essential systematic limitations is a tilt of
the entire tube as a result of temperature variation. This tilt can simultaneously be measured by the DWS
technique and can be used to correct the measurement. Using a Zerodur tube as a reference, it is shown that
this eect can be reduced in post processing to achieve a minimum CTE measurement sensitivity <10 ppb/K.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.