**5. Conclusions**

Three wide-aperture excimer laser systems created at HCEI were presented. The schemes of small powerful lasers pumped by electric discharge and electron beam were analyzed. It was shown that electron beam–pumped lasers are more efficient for long laser pulse duration (300 ns and more). The formation results of a high-quality and high-power radiation in UV and visible range were reported.

Based on the experimental data, we demonstrated that diffraction-limited laser beams with a large cross section can be amplified in the gas laser system. It was shown that the divergence of amplified UV beam was close to the diffraction-limited beam when its diameter was no greater than 5 cm. But the divergence increased with a further increase of diameter. The wave-front distortions on the turbulent flows in the laser mixture and air were the main reason for it. The minimum divergence of the laser beam 10 μrad was obtained. The pulse energy of the amplified UV radiation at a wavelength of 308 nm with 250 ns pulse duration was 330 J.

The output energy of 1 J was reached in the first pilot experiments of amplification of downchirped 1 ps pulses in femtosecond hybrid laser system THL-100. At the output energy of 0.7 J, the recompression of the amplified pulses in bulk fused silica to the initial duration of 50 fs was realized. This means that a record-breaking peak power ~ 14 TW in the visible spectrum has been attained.
