arXiv subjects

Nicholas R. Wenner

Publications and source records attributed to Nicholas R. Wenner.

3 recordsLinked to original sources

arXiv2026

Spec-S5: A Next-Generation All-Sky Spectroscopic Facility Enabling Large-Scale Surveys for Cosmology and Astrophysics

The Stage-5 Spectroscopic Experiment (Spec-S5) is a next-generation, all-sky spectroscopic facility designed to address fundamental questions in cosmology and astrophysics. Building on the legacy of the Dark Energy Spectroscopic Instrument (DESI), Spec-S5 will upgrade two existing 4-m telescopes into 6-m, wide-field observatories, each equipped with a highly multiplexed spectrograph capable of measuring 13,000 spectra simultaneously. This overview paper summarizes the science motivation, system architecture, and integration strategy of the project. Spec-S5 will deliver a more than tenfold increase in spectroscopic capability, enabling transformative surveys in the post-Rubin, post-DESI era and advancing our understanding of dark matter, dark energy, and cosmic structure formation.

astro-ph.IM↗

arXiv2026

Linear motion (R-FLEX) for minature 6.2 mm pitch optical fiber position robots with polar (R-theta) kinematics

R-FLEX is a compact, low-part-count flexure-based radial positioning mechanism designed for the next generation of massively parallel fiber-fed spectroscopic telescope instruments. Current instruments such as the Dark Energy Spectroscopic Instrument (DESI) employ 5,000 robotic fiber positioners at 10.4 mm pitch, whereas future surveys require 2.5-3x higher packing density, necessitating new positioning technologies. The R-FLEX mechanism converts small rotations at the flexure base into large, nearly tilt-free radial motion at the fiber tip, achieving naturally low-backlash linear motion within a compact 5.8 mm diameter package. Coupled with a rotating theta-stage, this enables overlapping circular patrol areas at 6.2 mm pitch, as envisioned for projects like Spec-S5. Development proceeded through parametric modeling and optimization, finite element analysis, fabrication, and prototype testing. Prototype units characterized by optical centroiding achieved a corrected radial accuracy consistently better than 4 um RMS over a 3.9 mm travel range, with maximum fiber tilt 0.092 deg, defocus 42 um over the required range, and durability over more than 400,000 targets per robot across operating and survival temperature extremes. Preliminary Spec-S5 accuracy, defocus, and fiber tilt requirements are specified for the complete R-theta robot, and these radial-stage results exceed those requirements, leaving margin for the companion theta-stage. A parametric optimization pipeline makes R-FLEX a versatile, mass-producible platform that can be re-optimized for precision-positioning applications beyond Spec-S5. This offers the precision, compactness, and reliability needed to collect hundreds of millions of spectra for new studies of the large-scale structure of the universe.

astro-ph.IM↗

arXiv2025

Design and performance of "R-FLEX", a flexure-based fiber positioning robot for spectroscopic cosmology

We present the design, fabrication, and testing of R-FLEX, a novel flexure mechanism for next-generation fiber-fed astronomical instruments. As the current Dark Energy Spectroscopic Instrument (DESI) revolutionizes cosmology with over 56 million collected spectra using 5,000 robotic fiber positioners at 10.4 mm pitch, we project that future instruments will require 2.5-3x smaller fiber robots by area. R-FLEX enables precision radial motion for fiber robots mountable at 6.2 mm pitch, delivering repeatable positioning accuracy $\leq$ 5 $μ$m over a 4 mm travel range. The travel range extends outside the robot's mechanical envelope, providing complete patrol coverage of the focal surface. The R-FLEX design must meet challenging requirements for parasitic motion < 30 $μ$m, angular misalignment < 0.3°, 1 million cycle lifetime, operating in a mountaintop telescope environment, and is suitable for mass production of $\sim$30,000 units.

astro-ph.IM↗