Fabrication of toroidal and coma-corrected toroidal diffraction gratings from spherical master gratings using elastically deformable substrates: a progress report
Abstract
A technique has been developed that permits toroidal, and coma-corrected toroidal, diffraction gratings to be replicated from spherical master gratings with the use of elastically-deformable substrates. Toroidal gratings correct astigmatism and, thus make it possible to construct stigmatic spectrometers that employ a single reflective diffraction grating. These spectrometers are particularly useful for the extreme-ultraviolet (EUV) wavelength range, where reflection coefficients are low, since the single optical surface provides for dispersion, focusing, and astigmatism correction. The fabrication procedures for the pure toroidal, and coma-corrected toroidal, gratings are described, and initial test results are presented. The use of the toroidal gratings in a high-resolution sounding-rocket EUV spectroheliometer (HiRES), and in both the coronal diagnostics spectrometer (CDS) and the ultraviolet coronagraph spectrometer (UVCS) on the ESA/NASA Solar and Heliospheric Observatory (SOHO) mission, is described briefly, and the use of this technique for the fabrication of a coma-corrected toroidal grating for the prime Rowland spectrograph of the FUSE/Lyman mission is discussed.
- Publication:
-
Space Astronomical Telescopes and Instruments
- Pub Date:
- September 1991
- DOI:
- 10.1117/12.46744
- Bibcode:
- 1991SPIE.1494..472H
- Keywords:
-
- Diffraction Patterns;
- Extreme Ultraviolet Radiation;
- Gratings (Spectra);
- Imaging Spectrometers;
- Emission Spectra;
- Spaceborne Astronomy;
- Substrates;
- Optics