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2023
Conference Paper
Titel
Optimization of diamond machined gratings for low light scattering and highest diffraction efficiencies
Abstract
Optical instruments for earth observation often rely on high performance spectroscopy. One key element in this technology is the dispersing element. Typically used grating designs in Littrow or Offner spectrometers are blazed or binary phase gratings. The diffraction efficiency of these elements is decisive for the radiometric accuracy of the instrument [1]. One highly effective and accurate technology for the manufacturing of optical gratings is diamond machining. It offers the opportunity to manufacture gratings even on curved base geometries. However, this is achieved by using at least three machine-controlled axes, all contributing to fabrication tolerances and thus reducing the accuracy of the grating shape [2]. The accuracy of the grating features is secured by the use of microscopic analysis and white light interferometry. But, besides of the error impact from mistuned geometric features, dispersive elements with their large surface area are susceptible to light scattering that leads to a reduced spectral purity and lower grating efficiencies. Especially diamond machining with two or more simultaneously moving linear or rotating axes is an excellent source for light scattering. This publication discusses the influence of the manufacturing technology on the grating performance by analysing their optical impact through light scattering measurements. Further, the paper demonstrates the possibility to enhance the performance of diamondmachined gratings by varying process variables as machine parameters or by changing the substrate material. It shows the potential of combining classic feature analysis with light scattering analysis to enhance the optical performance of dispersive elements significantly.
Author(s)