Wavefront Metrology Developments using Adaptive Optics and Debris Shield Wavefront Measurements

Summary form only given. A real-time closed feedback loop adaptive optics (AO) set-up has been developed for optical wave front qualification at Extreme Light Infrastructure - Nuclear Physics facility that hosts a dual arm 10 PW high power laser system [1]. The AO allows a dynamic wave front correction associated to optical components for high-peak ultra-short femtosecond laser systems. The AO set-up consists in (1) a Shack-Hartman wave front sensor (SHWFS), for measuring optical wave front deviations, (2) a deformable mirror (DM) that changes its shape in order to modify a distorted optical wave front, (3) a real-time closed control software to calculate the corresponding shape that the DM must assume in order to compensate the wave front distortions, and (4) a second SHWFS that provides wave front measuring capabilities for ~ 10 mm and 50 mm, respectively, laser beam diameter [2]. The experiments carried out with the AO set-up include qualification measurements of micrometer thin glasses to be used within the Large Beam Transport System (LBTS) and before focusing optics as irradiation debris shields for parabolic mirrors, as well as micrometer thick plastic films to be implemented in the High Power Laser System (HPLS) for spectral broadening in order to obtain a shorter pulse duration. The wave front qualification experiments have been performed on ultra -thin and malleable alkali -free borosilicate type glass plates of various thicknesses such as 100 gm and 200 pm, respectively, described by high -quality surface roughness and - 95% optical transmission at 800 nm. A preliminary result of the wave front distortion induced by a borosilicate glass plate using a - 10 mm aperture laser beam, is presented in Fig. 1. Further applications consist in implementation of an adaptive helical mirror within the AO platform in order to better simulate the focusing evolution of the distorted laser wave front laser through the qualified optical samples.