As illustrated [Fig. 6(b)], we see that in cycles using energy levels above , bowing during irradiation can differ significantly from bowing after irradiation has stopped. Bowing during the first irradiation cycle is different compared to the following cycles. Within a couple of hundreds of thousands pulses, the mirrors show a rapid positive bow change. However, after this initial phase, while the irradiation is ongoing, the initially positive direction of bow change turns negative. The higher the applied energy level, the quicker the turn around and the stronger the following negative change. Depending on the applied energy density, this negative change adds up to , , and , respectively, within the first . When the irradiation is stopped, the bow then slightly relaxes toward the initial value. This relaxation adds up to about 1 nm within the first hour. After each of the subsequent cycles, the bow becomes progressively more negative as compared to the starting state.