{'fraction_non_alphanumeric': 0.024193548387096774, 'fraction_numerical': 0.01488833746898263, 'mean_word_length': 5.086792452830188, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
SDSS-V local volume mapper objective optics

The Sloan Digital Sky Survey V (SDSS-V) is an all-sky spectroscopic survey of <6 million objects, designed to decode the history of the Milky Way, reveal the inner working of the stars, investigate the origin of solar systems, and track the growth of supermassive black holes across the Universe. The Local Volume Mapper (LVM) is one of three surveys that form SDSS-V, and it consists of four telescopes optimized for broad visible-wavelength coverage of 360-980 nm feeding three fiber-fed R∼4000 spectrographs. Each telescope comprises a siderostat and an optical table that hosts powered refracting optics in a triplet configuration, hardware for image de-rotation, image acquisition and guiding systems, and a focal plane assembly. The optical design of LVM balances the science requirements for broad wavelength coverage and spaxel size with the focal ratio imposed by the spectrograph fibers and microlenses. Initial design was completed and optimized in Zemax OpticStudio software. The resulting lenses were fabricated by a vendor and assembled at Carnegie Observatories. Final testing will be on-sky at Las Campanas Observatory in Chile during commissioning in 2022. The assembly process includes bonding of the triplet lenses using Dow Corning SYLGARD 184 Silicone Elastomer (“Sylgard 184”) and mounting in a cell that travels on a motorized focusing stage on the optical table. We present details of the Sylgard 184 bonding process, a basic bonding procedure, recovery from a stress feature in two bonds, and removal of Sylgard during imperfect applications.