Assembly, alignment, and testing of the DECam wide field corrector optics

The DES project is a 5 year imaging survey of the southern sky using the 4m Blanco Telescope at the Cerro Tololo International Observatory in Chile. A new wide field camera with a 2.2 degree diameter field of view has been built to undertake this survey. The alignment of the large lenses for this camera poses a significant challenge as they have to be aligned to a tolerance of ±50 micrometers. This paper presents the assembly and alignment process of the full optical system along with the test results. Also included is the predicted imaging performance from the as-built system.