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CHIME (Copernicus Hyperspectral Imaging Mission for the Environment) is part of ESA’s Sentinel Expansion Program for which OHB System AG in Oberpfaffenhofen, Germany has been selected as the instrument prime contractor. In this paper we present the development of the ultra-stable stiffness architecture for the instrument structure. Backed by a trade study of different structural concepts with a focus on the opto-mechanical decoupling, assembly integration and test accessibility, and the demanding optical performance criteria, we derive a robust solution: The main stiffness element is a central monolithic CFRP (Carbon Fiber Reinforced Plastic) torus, on which several sub-elements are mounted for precise positioning of the highly-sensitive optical elements, creating a modular 3D optical bench. We demonstrate the use of topology optimization for design concept finding considering mass and performance criteria. The paper concludes with the results from a breadboard test campaign and an outlook on the next development steps.

A Hosted Arctic Imager (HAI) concept is currently being investigated as part of ESA’s Polaris program. HAI intends to fulfil the needs for providing weather and atmospheric services in the polar regions enabling e.g. near-real-time observations of Atmospheric Motion Vectors of the Arctic and Nordic regions, similar to the measurements offered by its Meteosat counterparts in GEO, such as SEVIRI on MSG and FCI on MTG. The compact hosted-payload multispectral imager operates from a High Elliptical Orbit in 12 spectral bands from 0.4μm to 13.3μm at a Ground Sampling Distance of 1-3km. The optical concepts employs a split design into a wavelength-optimized VIS and a (N)IR telescope, built as all-metal free-form optics, where a hole in the first mirror of the (N)IR telescope presents the entrance aperture of the VIS telescope. Our instrument design maximizes the re-use of heritage technology, e.g. for detectors, scanner, and calibration elements, in order to enable a low-risk fast-track development program.

4MOST is a fibre-fed, multi-object spectroscopic survey facility to be installed on the VISTA telescope at ESO's Paranal observatory. This paper presents the final mechanical design of the optical fibre route from the fibre positioner at the focal plane of VISTA to the fibre-slits within the high- and low-resolution spectrographs below the azimuth platform. The technical challenges are to provide a safe, durable and efficient fibre route for over 2400 fibres. To accommodate the movements of the telescope, a Cassegrain Cable Wrap and a novel elevation chain concept has been prototyped and extensively tested to validate the design solutions.

4MOST (4-meter Multi-Object Spectroscopic Telescope) is a wide-field, fiber-feed, high-multiplex spectroscopic survey facility to be installed on the 4-meter ESO telescope VISTA in Chile. It consists of two identical low resolution spectrographs and one high resolution spectrograph. The instrument is presently in the preliminary design phase and expected to get operational end of 2022. The high resolution spectrograph will afford simultaneous observations of up to 812 targets - over a hexagonal field of view of ~ 4.1 sq.degrees on sky - with a spectral resolution R>18,000 covering a wavelength range from 393 to 679nm in three channels. In this paper we present the optical and mechanical design of the high resolution spectrograph (HRS) as prepared for the review at ESO, Garching. The expected performance including the highly multiplexed fiber slit concept is simulated and its impact on the optical performance given. We show the thermal and finite element analyses and the resulting stability of the spectrograph under operational conditions.

ARGOS is the Laser Guide Star and Wavefront sensing facility for the Large Binocular Telescope. With first laser light on sky in 2013, the system is currently undergoing commissioning at the telescope. We present the overall status and design, as well as first results on sky. Aiming for a wide field ground layer correction, ARGOS is designed as a multi- Rayleigh beacon adaptive optics system. A total of six powerful pulsed lasers are creating the laser guide stars in constellations above each of the LBTs primary mirrors. With a range gated detection in the wavefront sensors, and the adaptive correction by the deformable secondary’s, we expect ARGOS to enhance the image quality over a large range of seeing conditions. With the two wide field imaging and spectroscopic instruments LUCI1 and LUCI2 as receivers, a wide range of scientific programs will benefit from ARGOS. With an increased resolution, higher encircled energy, both imaging and MOS spectroscopy will be boosted in signal to noise by a large amount. Apart from the wide field correction ARGOS delivers in its ground layer mode, we already foresee the implementation of a hybrid Sodium with Rayleigh beacon combination for a diffraction limited AO performance.

ARGOS the Advanced Rayleigh guided Ground layer adaptive Optics System for the LBT (Large Binocular Telescope) is built by a German-Italian-American consortium. It will be a seeing reducer correcting the turbulence in the lower atmosphere over a field of 2' radius. In such way we expect to improve the spatial resolution over the seeing of about a factor of two and more and to increase the throughput for spectroscopy accordingly. In its initial implementation, ARGOS will feed the two near-infrared spectrograph and imager - LUCI I and LUCI II. The system consist of six Rayleigh lasers - three per eye of the LBT. The lasers are launched from the back of the adaptive secondary mirror of the LBT. ARGOS has one wavefront sensor unit per primary mirror of the LBT, each of the units with three Shack-Hartmann sensors, which are imaged on one detector. In 2010 and 2011, we already mounted parts of the instrument at the telescope to provide an environment for the main sub-systems. The commissioning of the instrument will start in 2012 in a staged approach. We will give an overview of ARGOS and its goals and report about the status and new challenges we encountered during the building phase. Finally we will give an outlook of the upcoming work, how we will operate it and further possibilities the system enables by design.

LUCIFER 1 is the rst of two identical camera-spectrograph units installed at the LBT (Large Binocular Telescope) on Mount Graham in Arizona. Its commissioning took place between September 2008 and November 2009 and has immediately been followed by science operations since December 2009. LUCIFER has a 4x4 arcminute eld of view. It is equipped with a 2048x2048 pixel HAWAII-2 array, suitable lters (broad-band z, J, H, K & Ks plus 12 medium and narrow band near-infrared lters) and three gratings for spectroscopy for a resolution of up to 15000. LUCIFER has 3 cameras: two specic for seeing limited imaging (the N3.75 camera, with 0.12"/pixel) and spectroscopy (the N1.8 camera, with 0.25"/pixel) and one for diraction limited observations (the N30 camera). We report here about the completed seeing-limited commissioning, thus using only two of the cameras.

The LUCIFER-MOS unit is the full cryogenic mask-exchange unit for the near-infrared multi-object spectrograph LUCIFER at the Large Binocular Telescope. We present the design and functionality of this unique device. In LUCIFER the masks are stored, handled, and placed in the focal plane under cryogenic conditions at all times, resulting in very low thermal background emission from the masks during observations. All mask manipulations are done by a novel cryogenic mask handling robot that can individually address up to 33 fixed and user-provided masks and place them in the focal plane with high accuracy. A complete mask exchange cycle is done in less than five minutes and can be run in every instrument position and state reducing instrument setup time during science observations to a minimum. Exchange of old and new MOS masks is likewise done under cryogenic conditions using a unique exchange drive mechanism and two auxiliary cryostats that attach to the main instrument cryostat.

LUCIFER1 is a NIR camera and spectrograph installed at the Large Binocular Telescope (LBT). Working in the wavelength range of 0.9-2.5micron, the instrument is designed for direct imaging and spectroscopy with 3 different cameras. A set of longslit masks as well as up to 23 user defined (MOS) masks are available. The set of user defined masks can be exchanged while the instrument is at operating temperature. Extensive tests have been done on the electro-mechanical functions, image motion due to flexure, optical quality, instrument software, calibration and especially on the multi-object spectroscopy. Also a detailed characterization of the instrument's properties in the different observing modes has been carried out. Results are presented and compared to the specifications.

LUCIFER is a NIR spectrograph and imager (wavelength range 0.9 to 2.5 micron) for the Large BinocularTelescope (LBT) on Mt. Graham, Arizona, working at cryogenic temperatures of less than 70K. Two instrumentsare built by a consortium of “ve German institutes and will be mounted at the bent Gregorian foci of the twoindividual telescope mirrors. Three exchangable cameras are available for imaging and spectroscopy: two ofthem are optimized for seeing-limited conditions, a third camera for the diraction limited case will be used withthe LBT adaptive secondary mirror working. Up to 33 exchangeable masks are available for longslit or multi-object spectroscopy (MOS) over the full “eld of vie w (FOV). Both MOS-units (LUCIFER 1 and LUCIFER2) and the auxiliary cryostats together with the control electronics have been completed. The observationalsoftware-package is in its “nal stage of preparation.After the total integration of LUCIFER 1 extensive tes ts were done for all electro-mechanical functions andthe veri“cation of the instrument started. The results of the tests are presented in detail and are compared withthe speci“cations.Keywords: Instrumentation, Infrared, Testing, Multi-Object Spectroscopy, Cryogenic Mechanisms