Study of a compact three-electrode oscillator-amplifier excimer laser system

We present the design and performance details of IANUS, a three-electrode XeCl excimer laser operated as a power-oscillator power-amplifier system, The oscillator, equipped with a generalised self-filtering unstable resonator, delivers a very low divergence laser beam, which is only 1.1 times its own diffraction limit and 1.3 times the diffraction limit of the equivalent gaussian beam. In spite of its long pulsewidth (85 ns FWHM), the single-pass amplified beam reaches a high radiance value of B = 3 x 10(14) W cm(-2) ster(-1). Both the oscillator and the amplified laser beam have excellent pointing stability. The limiting factors and the possible improvements of the IANUS performance are discussed.