抄録
Extension of lasing to shorter wavelengths, especially into the x-ray region, has been a longstandingsubject in the scientific research. After various efforts over many years, soft x-ray amplificationhas been demonstrated in 1984. Rapid progress has been made since then in improvingthe performance of the x-ray lasers. Recent development of the ultrashort, high powerlasers opens a new possibility for developing compact, high rep-rate x-ray lasers.
