Adaptive secondary P30 prototype: laboratory results

We present the result of electrical and optical measurements performed on a reduced size adaptive secondary prototype named P30. The design of this concave deformable mirror consists of a thin deformable glass shell whose figure is controlled by electromagnetic actuators and capacitive position senors. Static measurements of the mirror optical figure, performed with a commercial interferometer, have provided the calibration of the internal position sensor. Dynamic test were performed to experimentally derive the mechanical response of the mirror to the electromagnetic actuators in order to design the mirror closed loop control law. The test, although performed on a reduced scale, are representative of the complexity and capabilities of the full size mirror. In fact, all the key-elements of the full size mirror, i.e. central supporting membrane, actuator spacing closed loop control of the device, have been implemented on the prototype.