Suppression of higher diffraction orders in the extreme ultraviolet range by a reflective quasi-random square...

Higher diffraction orders of a grating introduce so-called harmonics contamination that leads to ambiguity in the spectral data. They are also present in "monochromatic" output beams processed by grating monochromators at synchrotron radiation facilities, making calibration results of optical elements and detectors imprecise. The paper describes a new design of a reflective quasi-random square nano-pillar array grating to reduce the amount of data of the grating relief pattern that is 10 cm in size and suppresses higher diffraction orders in the extreme ultraviolet range. In addition, a laboratory-scale grating monochromator equipped with the grating has been developed to test its spectroscopy characteristics at grazing incidence. The results illustrate that it can suppress higher diffraction orders and maintain the spectral resolving power as an ordinary grating at grazing incidence. The grating has great potential in harmonics suppression in the field of synchrotron radiation, spectral diagnostics of plasma, and astrophysics.