Powerful and novel telescope design is key to pushing the available limits of astronomical sciences and a segmented primary is an attractive approach. For the Nautilus Space mission, a segmented lens has been proposed to replace large monolithic primary optics for the purpose of survey faint objects like exo-planets as well as time-domain astrophysics observations. Enabling technology for Nautilus is an ultra-lightweight multi-order diffractive engineered (MODE) lens that replaces bulky primary mirrors. The MODE lens consists of multiple, identical, molded segments. This is because the complicated optical design of both the diffractive surfaces is not easily manufacturable by traditional fabrication methods. Besides, the molding approach for identical segmented optics allows for a cost-efficient process. Conversely, the fusion of segmented optics demands high precision metrology and a delicate assembly strategy. We propose an in-process metrology technique that mitigates post-assembly process complications. This system monitors the co-phase character of the segmented optics during UV cured assembly, guiding the overall process.
The LUCI (LBT Utility Camera in the Infrared) instruments are a pair of near infrared (NIR) imagers and spectrographs for the Large Binocular Telescope (LBT) that include a set of cryogenic exchangeable focal plane masks. Although LUCI covers the NIR zJHK bands at different resolutions with existing gratings, it is not currently possible to get zJHK in a single exposure with a single LUCI which is required for some planetary science programs. To produce a simultaneous zJHK spectrum with a single LUCI, we designed a system consisting of small and simple optical elements to fit within the limited space in the focal plane mask frame to cross-disperse fixed short slits. This system, called MOBIUS (Mask-Oriented Breadboard Implementation for Unscrambling Spectra), consists of a double-folding mirror, a collimating spherical mirror with 180 mm radius of curvature, and a dispersing prism with the rear surface mirror-coated. MOBIUS disperses the input slit perpendicular to the dispersion direction of the gratings in LUCI. The resulting order separation is at least ∼2.7 arcsecond, allowing a slit length of up to ∼2.3 arcsec without mixing orders at the LUCI image plane. Since MOBIUS would be introduced into the existing light path via the exchangeable slit mask mechanism, no modification to the current LUCI instrument is needed. Eventually, binocular observations combining one of the Multi-Object Double Spectrographs (MODS) with LUCI+MOBIUS at the LBT will provide simultaneous coverage from 0.3 to 2.4 μm for studies of asteroids and other faint solar system bodies.