Performance of laminar-type holographic grating for a soft X-ray flat field spectrograph in the 0.7-6 nm region

Koike, Masato; Sano, Kazuo*; Gullikson, E. M.*; Harada, Yoshihisa*; Kumata, Hideki*

Review of Scientific Instruments, 74(2), p.1156 - 1158, 2003/02

https://doi.org/10.1063/1.1533097

Laminar-type holographic grating having a groove density of 2400 lines/mm was designed and fabricated for use with a soft X-ray flat field spectrograph covering the 0.7-6 nm region. The varied-line-spaced grating pattern was generated by use of an aspheric wave-front recording system and the laminar-type grooves were formed by a reactive ion-etching method. The performance of the grating was evaluated by using a molybdenum K X-ray generator and a spectrograph with a CCD imaging detector. Also the absolute diffraction efficiencies of 0th, 1st, 2nd, and 3rd spectral orders were measured by use of the reflectometers installed at synchrotron radiation beamlines. The experimental results showed that the holographic grating indicated comparable spectral resolution and maximum first-order diffraction efficiency (2%) at 2 nm with a replica grating made from a mechanically ruled varied-line-spacing grating, and it also showed higher efficiency in 1.0nm region and lower level higher order light over the whole wavelength range than the replica grating.