18 August 2005 High resolution absorption spectroscopy using externally dispersed interferometry
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We describe the use of Externally Dispersed Interferometry (EDI) for high-resolution absorption spectroscopy. By adding a small fixed-delay interferometer to a dispersive spectrograph, a precise fiducial grid in wavelength is created over the entire spectrograph bandwidth. The fiducial grid interacts with narrow spectral features in the input spectrum to create a moire pattern. EDI uses the moire pattern to obtain new information about the spectra that is otherwise unavailable, thereby improving spectrograph performance. We describe the theory and practice of EDI spectrometers and demonstrate improvements in the spectral resolution of conventional spectrographs by a factor of 2 to 6. The improvement of spectral resolution offered by EDI can readily benefit space instruments operating from the near IR to the far UV by reducing spectrograph size or increasing instantaneous bandwidth.
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Jerry Edelstein, David J. Erskine, "High resolution absorption spectroscopy using externally dispersed interferometry", Proc. SPIE 5898, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XIV, 589811 (18 August 2005); doi: 10.1117/12.618061; https://doi.org/10.1117/12.618061

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