Large aperture adaptive optics development for ultra high intensity lasers

In this communication we present details of recent developments in adaptive optics at the central laser facility (CLF) for the Vulcan ultra high power laser system. Vulcan is a multibeam Nd:glass laser facility which has recently been upgraded to 1 Petawatt capability. Using the technique of chirped pulse amplification (CPA) on target intensities of 10²¹ Wcm^-2 are achievable. Adaptive optics plays a crucial role in achieving these intensities. A large aperture (130-mm) dynamic wavefront corrector has been developed within the CLF to meet these challenges. The adaptive optic is based on bi-morph technology developed in house and comprises a 64-element low voltage corrective mirror, run in a 10 Hz closed loop with a micro lens array wavefront sensor. The adaptive mirror has been successfully operated in Vulcan to correct the CPA beamline of the laser from 1.2 waves to 0.4 waves of aberration, and thus very close to the diffraction limit.