A transmission hologram for slitless spectrophotometry on a convergent telescope beam. 1. Focus and resolution

Journal Article · 21 July 2021 · Monthly Notices of the Royal Astronomical Society

DOI: https://doi.org/10.1093/mnras/stab2109 · OSTI ID:1982518

Moniez, M. ^[1]; Neveu, J.  ^[1]; Dagoret-Campagne, S. ^[1]; Gentet, Y. ^[2]; Le Guillou, L. ^[3]; Bongard, S. ^[4]; Copin, Y. ^[4]; Coughlin, M. ^[5]

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1. Université Paris-Saclay, Orsay (France)
2. Laboratoire Ultimate Holography, Saint-Aubin (France)
3. Sorbonne Univ., Paris (France)
4. LSST Dark Energy Science Collaboration (LSST DESC)
5. LSST Dark Energy Science Collaboration (LSST DESC), et al.

We report in this paper the test of a plane holographic optical element to be used as an aberration-corrected grating for a slitless spectrograph, inserted in a convergent telescope beam. Our long-term objective is the optimization of a specific hologram to switch the auxiliary telescope imager of the Vera Rubin Observatory into an accurate slitless spectrograph, dedicated to the atmospheric transmission measurement. We present and discuss here the promising results of tests performed with prototype holograms at the CTIO $$0.9\,$$m telescope during a run of 17 nights in 2017 May–June. After their on-sky geometrical characterization, the performances of the holograms as aberration-balanced dispersive optical elements have been established by analysing spectra obtained from spectrophotometric standard stars and narrow-band emitter planetary nebulae. Thanks to their additional optical function, our holographic disperser prototypes allow us to produce significantly better focused spectra within the full visible wavelength domain $$[370,1050]\,$$nm than a regular grating, which suffers from strong defocusing and aberrations when used in similar conditions. We show that the resolution of our slitless on-axis spectrograph equipped with the hologram approaches its theoretical performance. While estimating the benefits of a hologram for the spectrum resolution, the roadmap to produce a competitive holographic element for the Vera Rubin Observatory auxiliary telescope has been established.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
• Sponsoring Organization: USDOE
• Contributing Organization: The LSST Dark Energy Science Collaboration
• Grant/Contract Number: AC02-05CH11231; AC02-76SF00515
• OSTI ID: 1982518
• Journal Information: Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 4 Vol. 506; ISSN 0035-8711
• Publisher: Oxford University PressCopyright Statement
• Country of Publication: United States
• Language: English