Temporal wavefront stability of an ultrafast high-power laser beam.

We measured the temporal dynamics of wavefront aberrations in a beam produced by a commercial ultrafast high-power laser with a research-prototype real-time Hartmann-Shack wavefront sensor. Measurements were performed at two different temporal rates for a 7 mm diameter. Results showed that changes in the wavefront aberrations were always lower than 1%. The main contribution to the total root-mean-square (RMS) wavefront error was due to the effects of low order aberrations (defocus and astigmatism), which persisted even after cavity realignment. The potential improvement in the beam quality after correction of the different aberration modes was also shown. Real-time measurements of laser aberrations while modifying cavity parameters might be a useful tool to improve the beam quality.