A brief history of short wavelength coherent radiation sources

Almost contemporaneously with the building of the first optical laser at wavelength 694 nm in 1960, theoretical speculation and experiments were underway to produce lasing at shorter wavelengths in the x-ray range. This paper presents a brief review of plasma-based x-ray lasers. Plasma-based x-ray laser research has increased understanding of the atomic physics of plasmas and developed a suite of short wavelength lasers suitable for applications. The history of the development of soft x-ray lasers created by the irradiation of solid targets with pumping optical pulses is examined after setting the work in context with a summary of work covering a broad range of short wavelength coherent sources. The results of methods developed to characterise plasmas-based soft x-ray lasers are discussed.