Short stories of solutions no. 1/2007

Photo: A. Stephan


ZERODUR® secondary mirror sharpens the eye of the VLT in Chile

Modern astronomy could not do without adaptive telescope mirrors. Made from thin glass substrates, they can be adjusted as needed and, therefore, compensate for image distortions. After all, when the universe is viewed through a telescope, the light received is disturbed by atmospheric influences. As a result, the stars twinkle and appear diffuse.

This is why the eso (European Southern Observatory) has decided to use an adaptive secondary mirror for its Very Large Telescope (VLT) in Chile for the first time. The blank provided by SCHOTT, 1.15 meters in diameter, is thinned down and polished to only two millimeters in thickness and equipped with hundreds of actuators. Like the main 8.2 meter mirror located upstream, it also consists of SCHOTT ZERODUR® glass ceramic and will serve as a prototype for tomorrow’s extremely large telescopes.