Compact spectrometer for the analysis of high-harmonics content ofextreme-ultraviolet free-electron-laser radiation

摘要

We present the design and characterization of the spectrometer to be used at the FLASH facility (DESY, Hamburg) to characterize the spectral properties of free-electron-laser radiation in terms of high harmonics content. The spectrometer is sensitive in the 2-40 nm region. The optical design consists of two spherical gratings with variable groove spacing and a extreme-ultraviolet-enhanced CCD detector. The instrument design and characterization are presented.