VIEWPOINT Free - Electron Laser Does

L ight is perhaps the pre-eminent scientific tool, not just for observing objects but also for manipulating them. Near the visible part of the spectrum, conventional laser light is especially important thanks to its coherence and tunability, which give scientists fine control of the light beam in space and frequency. But conventional lasers do not operate in the extreme ultraviolet (XUV) wavelength band, usually defined as the range 10–100 nm, let alone at shorter wavelengths. Going beyond the ultraviolet would allow, for example, better imaging resolution to be obtained. One means of generating XUV radiation is the free-electron laser (FEL). FELs provide short-wavelength versions of many of the capabilities of conventional lasers, including coherence, polarization control, ultrashort pulse durations, and high intensities. In a new study, Primož Rebernik Ribič at the Elettra Sincrotrone Trieste research center in Italy and colleagues [1] have carried a different laser capability—vortex radiation [2]—over to XUV wavelengths for the first time with a FEL.