Ulrich Johann

TL;DR: In this paper, an optical dilatometer for high-accuracy and high-resolution absolute measurement of the linear coefficient of thermal expansion (CTEl) is presented, based on a highly symmetric differential heterodyne interferometer, where dimensional changes of a tubular shaped specimen under controlled thermal conditions can be characterized.

TL;DR: The first complete integration and testing of the space-qualified hardware and are the first tests on an optical system level were performed at the Albert Einstein Institute, Hannover, Germany as discussed by the authors.

TL;DR: In this paper, a high-sensitivity heterodyne interferometer implementing differential wavefront sensing for tilt measurement was developed over the last few years, using a baseplate made of Zerodur, a thermally and mechanically highly stable glass ceramic with a coefficient of thermal expansion (CTE) of 2 × 10−8 K−1, is presented.

TL;DR: The spacetime explorer and quantum equivalence principle space test satellite mission, proposed as a medium-size mission within the Cosmic Vision program of the European Space Agency (ESA), aims for testing general relativity with high precision in two experiments by performing a measurement of the gravitational redshift of the Sun and the Moon by comparing terrestrial clocks, and by performing the universality of free fall of matter waves in the gravitational field of Earth comparing the trajectory of two Bose-Einstein condensates of 85Rb and 87Rb as mentioned in this paper.