Abstract: A high average power, high brightness solid state laser system. A laser produces a first pulse laser beam with a high pulse frequency. A pulse spacing selector removes from the first pulse laser beam more than 80 percent of the pulses to produce a second pulse laser beam having a series of periodically spaced short pulses in excess of 1,000 pulses per second. A laser amplifier amplifies the second pulse train to produce an amplified pulse laser beam which is focused to produce pulses with brightness levels in excess of 10.sup.11 Watts/cm.sup.2. A preferred embodiment produces an amplified pulse laser beam having an average power in the range of 1 KW, an average pulse frequency of 12,000 pulses per second with pulses having brightness levels in excess of 10.sup.14 Watts/cm.sup.2 at a 20 .mu.m diameter spot which is steered rapidly to simulate a larger spot size. These beams are useful in producing X-ray sources for lithography.