Assembly integration and testing facility for the x-ray telescope of ATHENA

The optics of ATHENA (Advanced Telescope for High-ENergy Astrophysics) consists of several hundreds of Silicon Pore Optics mirror modules integrated and co-aligned onto a Mirror Assembly Module (MAM). The selected integration process exploits an optical bench to capture the focal plane image of each mirror module when illuminated by an UV plane wave at 218 nm. Each mirror module focuses the collimated beam onto a CCD camera placed at the 12 m focal position of the ATHENA telescope and the acquired point spread function is processed in real time to calculate the centroid position and intensity parameters. This information is used to guide the robot-assisted alignment sequence of the mirror modules. The ATHENA Assembly Integration and Testing (AIT) facility has been designed and is now under construction. It consists of a vertical tower, in which clean room conditions are maintained. Inside the tower, the MAM is supported at ground level on a gravity release system and a robot device above the MAM is used for alignment of the SPO Mirror modules. A paraboloid mirror that collects the light from an ultraviolet point source and generates a single reference plane wave large enough to illuminate the 2.6 m aperture of the X-ray telescope is placed 6 m below the MAM, whereas a CCD camera for the detection of the focused beam is placed at the top of the tower, 12 m above the MAM.