Multifacet echelle grating for intensity broadening on spectral plane fabricated by rotating ion-beam etching

This paper describes a new type of multifacet echelle grating (MFEG) for use in an echelle spectrometer. This new type of echelle grating broadens the spectral distribution on the spectral plane. We built a geometric model of MFEG to analyze the influence of the blaze angle and number of facet shapes on the spectral evolution. A dual-facet echelle grating and a four-facet echelle grating with different parameters were fabricated by rotating ion-beam etching with a self-shadowing rotating mask, based on the existing single-facet echelle grating (SFEG) with a line density of 52.7 g/mm and a blaze angle of 63.5°. The distributions of diffraction efficiency for different orders were measured with a He-Ne laser (632.8 nm); furthermore, these echelle gratings were applied in an echelle spectrometer (ICP-OES, Plasma2000), and testing spectra were obtained. The experimental results demonstrate that the MFEG can broaden the intensity distribution on the spectral plane, overcoming the weak spectral margin signal of SFEG spectrometers.