Two-pass ring amplifier with compensation of a thermally induced birefringence

A two-pass ring YAG amplifier without any active elements for the control of the beam was constructed. The amplifier was suitable for radiation with any time structure. Its operation was investigated in the course of pulsed amplification of radiation from a quasi-cw master oscillator. In this case the output radiation was a time-limited sequence of giant pulses with a controlled off-duty factor, which was particularly convenient in the drilling of holes by laser radiation.