Manufacturing and testing of the large lenses for Dark Energy Survey (DES) at SESO

After a brief introduction of what is the Dark Energy Survey (DES) project and which optical instrumentation will be used, the presentation will be mainly focused onto the optical production of the large lenses (up to 1m diameter) constituting the DES Camera (DECAM) located at the focal plane of the main observing telescope. Special emphasis will be made onto the optical manufacturing issues and interferometric testing solutions, including compensation of index inhomogeneities, which have been carried out by SESO especially for the biggest entrance lens (very challenging CV/CX meniscus named C1). Through several examples of typical past realizations or future possible ones for different astronomical projects requiring 1m-class optics, the presentation will conclude by a brief over review of the corresponding existing "state of the art" at SESO for these technologies.