{
  "abstract": "Significance: Fluorescence imaging remains largely qualitative and device-specific, limiting reproducibility and intersystem comparisons. SI-traceable radiometric characterization requires calibrated sources suitable for transferring known radiance to imaging systems. Aim: Establish and evaluate a compact, calibrated solid-state radiometric emitter target (RET) for SI-traceable radiance transfer, and assess methods for evaluating radiance invariance, imager responsivity, and extension of radiance transfer to digitally defined regions of interest (ROIs). Approach: The radiance invariance of an LED-based RET was evaluated by measuring its radiance across varying source-to-aperture distances and collection apertures. A previously described radiance-transfer formalism based on calibrated source radiance and collection geometry was implemented to determine imager responsivity (R{lambda}), which was evaluated across varying working distances and lens apertures. Grubbs and MAD outlier tests and one-way ANOVA were used to assess radiance and responsivity invariance. Finally, responsivity obtained using digitally defined ROIs was compared with matched physical apertures to assess ROI-based radiance transfer. Results: The measured RET radiance remained invariant across the tested source-to-aperture distances and collection apertures, with no significant differences observed across distance (p = 0.88) or aperture (p = 0.15). Imager responsivity remained stable across working distances for both tested lens configurations (p = 0.48 and p > 0.99). Responsivity was also invariant across lens apertures, except for deviations at f/11 that were consistent with practical aperture tolerances. Digitally defined ROIs reproduced responsivity values obtained using matched physical apertures, demonstrating that the radiance-transfer approach can be extended to image-defined regions. Conclusions: The presented methods provide an approach for evaluating compact LED-based sources for invariant-radiance emission and suitability for SI-traceable radiance transfer. The characterized RET supported stable imager responsivity across changes in imaging geometry and extension to digitally defined ROIs. These methods can be adapted to other LED-based sources, with further angular characterization and uncertainty analysis needed to establish broader applicability.",
  "abstract_shown": true,
  "affiliations": [
    "QUEL Imaging"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "A. J. Ruiz"
    },
    {
      "name": "E. A. Robledo"
    },
    {
      "name": "E. A. Littler"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/frqbjw0vgzw44.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.09.27.754831",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.09.27.754831v1.full",
  "id": "frqbjw0vgzw44",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.09.27.754831v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "bioengineering"
    ],
    [
      "openalex",
      "2202|Calibration and Measurement Techniques"
    ]
  ],
  "openalex": "W7214604717",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.09.27.754831v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-27",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/frqbjw0vgzw44.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:24:51Z",
      "native_id": "10.64898/2026.09.27.754831",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.09.27.754831v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "biorxiv:bioengineering",
      "subfield": "systems-synthetic"
    }
  ],
  "title": "Radiance-Invariance Evaluation of a Compact LED-Based Source for Imager Radiance Transfer",
  "title_text": "Radiance-Invariance Evaluation of a Compact LED-Based Source for Imager Radiance Transfer",
  "type": "preprint",
  "updated_at": "2026-10-30T12:24:51Z",
  "url": "https://research.draconitic.com/paper/frqbjw0vgzw44",
  "venue": "bioRxiv",
  "versions": []
}