Multi-actuator adaptive lens in astronomy: in lab test results

Multi-actuator Adaptive Lenses have been recently utilized for the implementation of Adaptive Optics in different scientific fields such as microscopy, in vivo ophthalmic imaging applications or high power laser beam shaping. A multi-actuator adaptive lens is composed by two thin glass plates bonded to two piezoelectric rings with 18 actuators. The space between the two glass plates is filled with a transparent liquid and the actuation of the lens allows a wavefront modulation up to the 4th order of Zernike polynomials with a relatively fast time response (frequency up to 200Hz). These features allow using the adaptive lens in closed loop with wavefront sensor as if it were a deformable mirror. Despite the adaptive lenses performances do not allow their use in extreme astronomical instrumentation as substitutes for deformable mirrors, they are the ideal device for the correction of the non-common path aberrations in order to maximize the performances of the pyramid wavefront sensor. In this paper, we present the laboratory results of a characterization campaign of an adaptive lens prototype manufactured for astronomical applications and its use to correct non-common path aberrations to enhance pyramid wavefront sensor sensitivity.