Abstract
Blazed gratings are of dedicated interest for the monochromatization of synchrotron radiation when a high photon flux is required, such as, for example, in resonant inelastic X-ray scattering experiments or when the use of laminar gratings is excluded due to too high flux densities and expected damage, for example at free-electron laser beamlines. Their availability became a bottleneck since the decommissioning of the grating manufacture facility at Carl Zeiss in Oberkochen. To resolve this situation a new technological laboratory was established at the Helmholtz Zentrum Berlin, including instrumentation from Carl Zeiss. Besides the upgraded ZEISS equipment, an advanced grating production line has been developed, including a new ultra-precise ruling machine, ion etching technology as well as laser interference lithography. While the old ZEISS ruling machine GTM-6 allows ruling for a grating length up to 170 mm, the new GTM-24 will have the capacity for 600 mm (24 inch) gratings with groove densities between 50 lines mm-1 and 1200 lines mm-1. A new ion etching machine with a scanning radiofrequency excited ion beam (HF) source allows gratings to be etched into substrates of up to 500 mm length. For a final at-wavelength characterization, a new reflectometer at a new Optics beamline at the BESSY-II storage ring is under operation. This paper reports on the status of the grating fabrication, the measured quality of fabricated items by ex situ and insitu metrology, and future development goals.
Highlights
Diffraction gratings are key components in the application of UV, VUV and soft X-ray radiation at synchrotron radiation and free-electron laser (FEL) facilities
Based on a cooperation agreement between Zeiss and the Helmholtz Zentrum Berlin (HZB), a technology line was established in Berlin to provide and develop diffraction gratings for synchrotron, FEL and astronomy applications
This paper describes the technological processes necessary for a successful manufacture and metrology of gratings starting with the preparation and metrology of grating blanks (x2), and the required nano-technology for laminar gratings (x3) and blazed gratings (x4)
Summary
Diffraction gratings are key components in the application of UV, VUV and soft X-ray radiation at synchrotron radiation and free-electron laser (FEL) facilities. Photondiag2017 workshop density variation in one or two dimensions is defined by a higher-order polynomial (Harada et al, 1984; Reininger, 2011) The manufacture of such optical components which have a laminar or a blazed groove profile requires a complex nano-technological process line including ultra-precise metrology, a groove-shaping process of utmost precision as well as ion beam etching (IBE) to etch the final groove profile into the substrate (Nelles et al, 2001). Such gratings are usually processed on substrates of quartz glass or single-crystal silicon. A fast qualitative check to monitor this parameter is possible by aligning the grating under the Littrow condition in front of a Fizeau phase-shifting interferometer which allows viewing of the quality of the wavefront in higher diffraction order (Loechel et al, 2013)
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