Wavefront Correction in Vacuum of SULF-1PW Laser Beamline

The focusing quality of high peak power lasers plays a crucial role in laser wakefield electron acceleration investigations. We report here an improvement in the focusing quality of the SULF-1PW laser beamline, planning to drive and generate 5 similar to 10 GeV electron beams. After the wavefront correction in vacuum with an adaptive optical system and the focusing with an f/56 off-axis parabolic mirror, near-diffraction-limited focal spots with a size of 52 x 54 mu m(2) at full width at half maximum are achieved, and the enclosed energy inside this size is similar to 36.6%. Consequently, the focused intensity of similar to 1.66 x 10(19) W/cm(2) can be achieved at 1 PW peak power. Moreover, we also examine the wavefront stability in air and vacuum, respectively. From the statistical analysis of 1900 shots of successive laser pulses at 1 Hz, we identify the wavefront fluctuation resulting from air turbulence and the better correction capacity in vacuum. This work demonstrates the importance and necessity of wavefront correction in vacuum for high peak power lasers.