Corning and L3Harris build largest convex mirror for Rubin Observatory

20 Aug 2024

3.5 meter-wide, 680 kg glass mirror to help provide deepest views of the Universe.

Glass and glass products manufacturer Corning and defense technologies firm L3Harris Technologies have announced the successful installation of a jointly-produced a 3.5 m-wide, 680 kg glass mirror (11 ft, 1,500 lb) onto the NSF-DOE Vera C. Rubin Observatory in Chile. The mirror, designed and produced in New York State, is the largest convex mirror now in operation, says Corning.

The Rubin Observatory is now one step closer to capturing images of outer space that will allow scientists to identify 10 to 100 times more objects in the solar system, including potentially harmful asteroids. “It will also provide scientists with data that could answer some of the most pressing questions about the Universe,” added the Corning-L3 Harris statement.

Claude Echahamian, VP & General Manager, Corning Advanced Optics, commented, “As part of our latest collaboration, Corning’s team in New York manufactured a telescope mirror made of Corning ULE Glass (Ultra-Low Expansion Glass) glass that will enable crystal clear views of deep space and help scientists reveal millions of previously unknown Solar System objects with more details than ever before.”

‘Century of experience’

The mirror was manufactured in Canton, N.Y., using ULE glass, a titania-silicate glass material invented by Corning in the 1960s with near-zero expansion characteristics – critical to ensuring the telescope keeps its focus. The company said it had “tapped into a century of experience in large-aperture telescope fabrication to create the complex, innovative technology”.

Following that, L3Harris fine-ground, polished and finished the mirror in Rochester, N.Y.. The secondary process is key to the telescope’s performance. L3Harris also designed and built the secondary-mirror assembly, which consists of a stiff-steel mounting plate, 72 axial and six tangent actuators, the mirror-cell electronics and sensors, a thermal control system, and the mirror-control system.

Charles Clarkson, VP and General Manager, Imaging Systems, Space and Airborne Systems, L3Harris, said, “For nearly six decades we have designed and constructed high-end optical systems for space and ground applications. This work continues with the world’s largest active secondary mirror system, built for Rubin Observatory.

“With this milestone, we are closer to pushing scientific frontiers and charting the universe like never before, and we look forward to the science that will be discovered.”

Following funding from the U.S. National Science Foundation and the U.S. Department of Energy, the Rubin Observatory will offer the most comprehensive view of the universe from the Southern Hemisphere than all previous ground-based telescopes combined. The observatory is expected to be fully operational in 2025.