Prototype of part of the adaptive support system of the E-ELT

This picture shows a prototype of part of the adaptive support system for the M4 mirror of the E-ELT. It is equivalent in size to 1/14th of the final M4 mirror. The prototype has 350 actuators and co-located sensors. A small section of the thin mirror shell is mounted on the left part of the prototype in the picture. On the right the reference surface is visible as well as the sensors. The actuators are positioned inside the holes of the reference surface. This prototype system has shown very good performance, in line with the challenging requirements for M4.