Lsst Mirror System Status: From Design To Fabrication And Integration

In the construction phase since 2014, the Large Synoptic Survey Telescope (LSST) is an 8.4 meter diameter wide-field (3.5 degrees) survey telescope located on the summit of Cerro Pachon in Chile. The reflective telescope uses an 8.4 m f/1.06 concave primary, an annular 3.4 m meniscus convex aspheric secondary and a 5.2 m concave tertiary. The primary and tertiary mirrors are aspheric surfaces figured from a monolithic substrate and referred to as the M1M3 mirror. This unique design offers significant advantages in the reduction of degrees of freedom, improved structural stiffness for the otherwise annular surfaces, and enables a very compact design. The three-mirror system feeds a three-element refractive corrector to produce a 3.5 degree diameter field of view on a 64 cm diameter flat focal surface. This paper describes the current status of the mirror system components and provides an overview of the upcoming milestones including the mirror coating and the mirror system integrated tests prior to summit integration.