The Institut für Sonnenphysik (KIS) located in Freiburg, Germany, has installed a high-precision measuring instrument for the world's largest solar telescope, the U.S. National Science Foundation (NSF ...

Fig. 1: Measurement setup of first FPI showing the two glass plates with a diameter of 0.3 m and the gap between them which is about 0.5 mm wide and is tuned to sub-nanometer accuracy in order to ...