Characterization of a novel two-stage KrF laser with high-pulse energy and low-beam divergence

We present experimental results on the performance of a novel two-stage KrF excimer laser designed and constructed to drive a laser plasma XUV source, an application which requires high pulse energy and high beam quality in order to produce XUV radiation with high efficiency. The system consists of two high power laser modules that can be configured as power oscillator-power amplifier (popa), or as an injection seeded system. In the first case the pulse energy and beam divergence amount to 1.5 J and 0.15 X 0.12 mrad (FWHM), respectively, in the second case 0.95 J and 0.07 X 0.13 mrad. At 50 Hz the power amounts to 67 and 42 W. Progress in excimer laser engineering has led to many improvements that give more reliability at higher pulse energies and higher average power, while maintaining beam properties essential for the application under study. The aim of this work is to develop the laser plasma for x-ray lithography, i.e., to construct a prototype source with a high XUV flux as an alternative to electron storage rings.