Seminars at FGG

M4 Adaptive Unit Conceptual Design, Prototyping & Preliminary Design of the Optical Test

Speaker: Daniela Tresoldi (Università dell'Insubria)

Date and time: 2009-03-30 11:00

With the optical test we want to sample the flatness of the M4 Adaptive Unit of the E-ELT and of Demonstration Prototype and the corresponding flattening procedure. The requirements to achieve are: WFE (rms) <15 nm for scales smaller than twice inter-actuator spacing and <20 nm for larger scales. Three different sub-systems have been studied, analyzed and optimized that will give all the required information to validate the performances of the Adaptive Unit. • The first sub-system is a stitching interferometric setup (SIS) that will give high spatial resolution. • The second sub-system is a Ritchey-Common test setup. In this way we are able to cover a portion equal to about 55% of the surface of the DP. • The third sub-system is a piston-sensing device (PSD), which will be used to measure the relative piston between the two adjacent optical shells of the DP unit.