In a significant development, the European Southern Observatory (ESO) has commenced the assembly of the largest optical telescope in the world. The initial shipment of 18 segments of the primary mirror, known as M1, for the Extremely Large Telescope (ELT) has been sent from France to Chile. Once completed, the ELT mirror will consist of a whopping 798 hexagonal segments, making it the largest of its kind worldwide, with a diameter exceeding 39 meters.
The final phase of manufacturing the mirror segments M1, involving their polishing, has been entrusted to Safran Reosc, a company specializing in optical systems. For this complex task, the company has dedicated a specially converted building to accommodate the project’s requirements. Innovative techniques for production automation and measurement have been developed to meet the stringent standards for mirror polishing. Leveraging modern technologies, Safran Reosc has successfully reduced surface irregularities to less than 10 nanometers, which is less than one-thousandth the thickness of a human hair. Ion-beam processing, a cutting-edge technique that eliminates irregularities at the atomic level, has been employed to achieve this unparalleled level of precision. As of November 1, 2023, Safran Reosc has already produced 100 mirror segments at a rate of four elements per week.
The ELT holds immense promise in addressing some of the most vital questions in astronomy today. It will facilitate the study of the solar system, exoplanets, stars, galaxies, and black holes, revolutionizing our understanding of the cosmos. Additionally, the main mirror of the ELT, M1, will capture details that are millions of times more precise than what the human eye can perceive.
The ELT telescope is set to achieve its first technical light in 2028. It will be situated 20 kilometers away from the Very Large Telescope on Mount Cerro Armazones, establishing itself as one of the most advanced astronomical tools available.