High-dispersion TIR-GRISMs with flattened angular dispersion profile
Martin Heusinger, Thomas Flügel-Paul, Kevin Grabowski, Dirk Michaelis, Stefan Risse, Uwe D. Zeitner
Abstract
Modern grating imaging spectrographs typically show aberrations due to the nonlinear dependence of angular dispersion on wavelength. This error can be reduced by a combination of diffracting and refracting components (grating and prism). Here, we present a dispersive optical component, namely, total internal reflection (TIR) grating + prism, with a grating attached to one facet of a prism. The elements work within the limit of TIR and exhibit three advantages compared to standard diffraction gratings: first, high diffraction efficiency up to 98%; second, enormous angular dispersion up to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msup> <mml:mn>0.75</mml:mn> <mml:mo>∘</mml:mo> </mml:msup> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">n</mml:mi> </mml:mrow> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> ; and third, a nearly constant angular dispersion profile. As an example, the fabrication of such a disperser designed for the short-wave infrared2 spectral range is demonstrated. We report on details of the manufacturing process, which relies on a dedicated combination of technologies, i.e., electron beam lithography, atomic layer deposition, and hydrophilic direct bonding.