Spectroscopic measurement and evaluation study on soft x-ray optical elements. Development of laminar-type replica grating for a soft x-ray flat field spectrograph

Laminar-type varied-line-spacing gratings had been developed with the holographic method. The performance of the original gratings also had been investigated comparing with mechanically ruled replica gratings and it was found that new gratins have advantages on suppress the higher order light and stray light over the replica gratings. In this study, we fabricated a replica grating from the master holographic grating having a groove density of 1200 lines/mm because of their higher productivity and marketability than the original grating. The diffraction efficiency and the spectral resolution of the replica grating as well as the master holographic grating and the mechanically ruled replica grating were measured in a spectral range of 5-18 nm by use of a synchrotron light source and a laboratory soft X-ray generator emitting the C-K band (4.36 nm), respectively. The replica grating showed equivalent diffraction efficiency and spectral resolution with those of the master grating without significant deterioration due to replication. (author)