In this paper, we present Yb:KLuW thin disk regenerative amplifier. Due to the relatively low astigmatic convex curvature of 7 m by 22 m of the thin disk we have been able to realize three foldings without mode compensating effort. A maximum pulse energy of 102 µJ after compression was extracted. At a repetition rate of 20 kHz we achieved a pulse duration of 255 fs what is about 7\% over the Fourier limit.