{
  "abstract": "The Hobby--Eberly Telescope High Resolution Spectrograph (HET--HRS) is undergoing a major instrument upgrade to improve its performance over the 360--1000 nm wavelength range. As part of this effort, a new fiber-feed system has been developed to increase throughput and enhance illumination stability. This paper presents the optical and opto-mechanical designs of the upgraded HRS Input Head Module Package and lens-based Double Scramblers. The Input Head incorporates a static Atmospheric Dispersion Corrector (ADC) and relay optics optimized for the HET operational zenith-angle range, reducing the residual atmospheric dispersion to less than 0.42 arcsec while improving wavelength-dependent fiber coupling. Separate Double Scrambler designs were developed for the 260 \\textmu m and 320 \\textmu m science fibers to exchange the near-field and far-field illumination distributions. Geometrical image analyses demonstrate stable near-field and far-field illumination, reduced coupling losses, and acceptable angular acceptance across both fiber geometries. The opto-mechanical designs supporting the Input Head and Double Scrambler are also presented to provide the alignment accuracy and mechanical stability required for the upgraded fiber-feed system. These results establish the proposed architecture as a practical solution for improving the optical performance and illumination stability of HET--HRS.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.16505",
  "author_total": 4,
  "authors": [
    {
      "name": "Devika K Divakar"
    },
    {
      "name": "Joseph Strubhar"
    },
    {
      "name": "Andrew Pinckney"
    },
    {
      "name": "Phillip MacQueen"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7wxdj2y9c1fwt.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.16505",
  "fulltext_url": null,
  "id": "7wxdj2y9c1fwt",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.16505",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.IM"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.16505",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-15",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7wxdj2y9c1fwt.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:41Z",
      "native_id": "2609.16505",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.16505"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    }
  ],
  "title": "Design of an atmospheric dispersion corrector and double scrambler for improved fiber coupling and illumination uniformity for the HET HRS",
  "title_text": "Design of an atmospheric dispersion corrector and double scrambler for improved fiber coupling and illumination uniformity for the HET HRS",
  "type": "preprint",
  "updated_at": "2026-10-30T12:21:41Z",
  "url": "https://research.draconitic.com/paper/7wxdj2y9c1fwt",
  "venue": "arXiv",
  "versions": []
}