The program met the goal producing ultrahigh precision spectroscopy exploiting a new XUV source that I will realize in the framework of an ERC staring grant. The high harmonics generation was placed directly inside the intra-cavity multi-kilowatt beam of a femtosecond laser that operates at multi-megahertz repetition rates. While the ERC project has targeting the proof-of-principle demonstration of high power intra-laser HHG, with this proposal, we want to enable new directions in XUV frequency comb spectroscopy. In the first year, we will focus on understanding the optimum stability parameters of a thin disk laser in intracavity operation. We will experimentally investigate noise properties and target the demonstration of stable IR driving frequency comb at unprecedented high intracavity power levels.