Time-compensated extreme-UV and soft x-ray monochromator for ultrashort high-order harmonic pulses

The optical design of a time-compensated monochromator for high-order harmo nic pulses in the extreme-UV (EU-V) and soft x-ray regions is presented. Th e system consists of two grazing-incidence mirrors used as collimating and refocusing elements and two multilayer normal-incidence plane mirrors illum inated in parallel light that rotate along a vertical axis parallel to thei r planes to select the wavelength, and remain parallel to guarantee the con stant direction of the exit beam: this is performed by rotating and transla ting, at the same time, one of the two mirrors along an axis parallel to th e exit direction. The system has constant exit direction in the whole worki ng spectral region. The pulse time duration is not altered up to few femtos econds. A system operating in the 9-32 nm region is described.