ABSTRACT
Since the first demonstration of the laboratory x-ray lasers 20 years ago (Matthews 1985, Suckewer 1985), there has been significant progress in demonstrating x-ray amplification based on various pumping schemes, characterizing and improving their performances, and developing the x-ray laser applications. Especially noteworthy in recent years is the rapid progress in developing compact x-ray lasers. In this report, historical perspective of the x-ray laser research is given, with emphases on major achievements, recent progress and interesting physics issues some of which remain unresolved.
