The greatest challenge in the amplification of laser pulses is the correction of the astigmatic thermal lens of a flashlight-pumped and water-cooled laser medium.A special arrangement of prisms and lenses solves the problem. First, two spherical lenses correct the thermal lens as if it were free from astigmatism. Astigmatism proper is compensated by a special combination of prisms turning laser pulses in every orbit in such a way that astigmatism removes distortion from the distorted beam profile. This is achieved independent of the power of the thermal lens and the degree of astigmatism. This property turns out to be very advantageous especially when variable pumping energies are used. In combination with a Pockels cell and a Glan prism, this special combination of prisms at the same time acts as an optical switch for covering laser pulses into and out of the ring resonator and removing them. Anti-astigmatic compensation can be used for all ring resonators with astigmatic laser media.