arXiv subjects

Jörg-Uwe Pott

Publications and source records attributed to Jörg-Uwe Pott.

At least 19 recordsLinked to original sources

arXiv2026

Shocks, Winds, and a Torus: The Large Binocular Telescope Interferometer (LBTI) Resolves the Active Nucleus of NGC 4151

We present mid-infrared (MIR) observations of the Seyfert 1 galaxy NGC 4151 using the Large Binocular Telescope Interferometer (LBTI). We took open-loop Fizeau images with 66-104 mas (5.8-9.1 pc) resolution in the N-band (at $8.7$ and $10.5~μm$), using the full resolution of the LBTI -- equivalent to that of a 28.8 m telescope. These images were complemented by AO imaging in the LM-bands ($3.7$ and $4.8~μm$), with 50-62 mas (4.4-5.4 pc) resolution. These images bridge the scales between previous Very Large Telescope Interferometer (VLTI)/MIDI and VLT/VISIR data, delivering ELT-like imaging resolution in the N-band. We resolve a dusty torus, (diameter 32 pc, PA$=125^{\circ}$), and detect dusty clouds within the narrow line region. Matching the resolution across four bands, we measured spatially-resolved SEDs of the central $\sim 100$ pc. Modified blackbody fitting revealed dust temperature and extinction profiles, indicating both heating from the accretion disk and additional shock heating due to the radio jet. The spatial coincidence of ionized emission (e.g., [Fe II] and [O III]), extended MIR structures, and radio features further supports the interpretation of shock heating. Comparison with NGC 1068 tests the Unified Model of Active Galactic Nuclei (Unified Model of AGN): Structures are similar, despite differences in orientation and Eddington ratio. NGC 4151's torus is smaller than NGC 1068's following a $r\propto L^{0.5}$ scaling. These thirty-meter-telescope class observations of NGC 4151 and NGC 1068 highlight the need to revise MIR radiative transfer models of AGN to account for jet-related heating.

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arXiv2025

Broad line region echo from highly accreting intermediate-mass black hole candidate SDSS J144850.08+160803.1. The first probe of intra-night variability and reverberation mapping

Elusive intermediate-mass black holes (IMBHs) can be used as ``time-squeezing'' machines, enabling studies of AGN geometry via reverberation mapping on much shorter timescales than their supermassive siblings. Constraints on the BLR radius for IMBH candidates across a broad range of Eddington ratios help probe the unexplored faint end of the radius-luminosity ($R-L$) relation in AGNs. This opens up the opportunity to build a more robust $M_{BH}$ estimator. The present study is aimed at: (a) confirming a highly accreting IMBH candidate and (b) demonstrating the feasibility of the first photometric BLR RM campaign for IMBHs with high Eddington rates. SDSS J144850.08+160803.1 was identified as an IMBH candidate from a broad H$α$-selected spectroscopic sample from SDSS. We carried out XMM-Newton X-ray observations to confirm its AGN status, along with narrowband H$α$ and broadband SDSS g' monitoring over five months (March-July 2024) using a 60-cm telescope at the Caucasus Mountain Observatory. These time series allowed us both to probe the short-timescale variability and extract the time lag between the BLR and AD continuum. XMM-Newton detected J1448+16 as a bright X-ray point source with a photon index of $Γ= 2.32^{+0.15}_{-0.13}$ and X-ray luminosity of $L_{2-10\,\rm{keV}}=(3.3^{+0.5}_{-0.4})\times10^{41}$ erg s$^{-1}$, confirming its AGN activity. From the SDSS optical spectrum and X-ray properties, we estimated a BH mass of $\sim(0.9-2.4)~\times10^{5}M_{\odot}$ and Eddington rate of $\sim37-112\%$. We report high-amplitude $\sim55\%$ intra-night ($\sim1.7$~h) H$α$ variability for this IMBH and extract a tentative BLR RM radius estimate of $\sim1-8~\mathrm{days}$. This work is a proof of concept for further high-Eddington-rate IMBH variability studies and BLR RM campaigns, which will be essential for an efficient calibration of the $R-L$ relation at the faint end.

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arXiv2025

Modal Identification of Mirror Vibrations at the VLT using Accelerometer Data

Recent advances in ground-based astronomy have made it possible to create optical telescopes with primary mirrors up to 40 m in size. With growing mirror diameter, the suppression of non-atmospheric disturbances becomes increasingly important. Precise knowledge of the movement of telescope mirrors is essential for understanding and compensating for vibration-based perturbations. A model from VLT accelerometer data for each individual mirror is developed, while the influence of wind buffeting is accounted for by a von Karman wind model. To describe the relevant rigid body motion, we consider the piston, tip and tilt modes of the mirrors. The identification is validated by comparing the power spectral density of the measured and identified modes. Additionally, we assess the robustness of the approach by calculating the identification error over different sections of the data. The study indicates that the employed methods are adequate for the identification of modal telescope vibrations. It is anticipated that said findings will serve as a significant foundation for the development of advanced model-based AO controllers for large telescopes, such as linear quadratic Gaussian control.

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arXiv2025

Simulation of Wavefront-based Disturbance Observers for Large Telescopes

The performance of future observatories such as the Extremely Large Telescope is mainly limited by atmospheric turbulence and structural vibrations of the optical assembly. To further enhance the mitigation performance of adaptive optics, real-time information about the disturbances acting on the control loop is needed. Current systems therefore employ a combination of wavefront sensor- and accelerometer-based filters. In this work, methods using only data from natural- and laser guide star (NGS, LGS) measurements are presented, as telescopes like the Very Large Telescope already have multiple fast and high-resolution wavefront sensors installed. This approach also avoids the costly installation and operation of additional accelerometers on the optical elements. We introduce two innovative disturbance observer schemes to sense both turbulence and vibration information. A multi-rate estimator for atmospheric influences is based on Kalman filter theory and can incorporate NGS and LGS signals at different loop rates. The estimator for structural perturbations uses Gaussian process regression and can be implemented in an offline and online configuration. We validate the filter designs with data from a realistic end-to-end adaptive optics model with randomly generated turbulence and vibrations. The simulation is fed with on-sky data from the Adaptive Optics Facility of the Very Large Telescope. The presented disturbance observer schemes demonstrate promising results and may be considered as potential alternatives or extensions to existing techniques such as linear-quadratic controllers with Kalman filtering (LQG).

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arXiv2025

Direct imaging of AGN outflows and their origin with the 23 m Large Binocular Telescope

Active galactic nuclei (AGNs) are a key component of galaxy evolution due to feedback on the host from its supermassive black hole. The morphology of warm, in- and outflowing dusty material can reveal the nature of the onset of feedback, AGN feeding, and the unified model of AGN. Here we use the Large Binocular Telescope Interferometer (LBTI) to image the dense, obscuring disk and extended dusty outflow region of NGC 1068. In Fizeau imaging mode the LBTI synthesizes the equivalent resolution of a 22.8 m telescope. The 8.7 $μ$m Fizeau images of NGC 1068 {have an effective resolution of $47\times90$ mas ($3.3\times6.2$ pc)} in a 5" field of view after performing PSF deconvolution techniques described here. This is the only extragalactic source to be Fizeau imaged using the LBTI, and the images bridge the scales measured with the Very Large Telescope Interferometer (VLTI; 0.5-5 pc) and those of single telescopes such as JWST and Keck ($>15$ pc). The images detect and spatially resolve the low surface brightness mid-infrared (MIR) features in the AGN disk/wind region that are over-resolved by the VLTI. The images show strong correlation between MIR dust emission and near-infrared (NIR) emission of highly excited atomic lines observed by SINFONI. Such LBTI imaging is a precursor to infrared imaging using the upcoming generation of extremely large telescopes, with angular resolutions up to 6x better than JWST, the largest space telescope in orbit.

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arXiv2023

The dusty heart of Circinus II. Scrutinizing the LM-band dust morphology using MATISSE

In this paper we present the first-ever $L$- and $M$-band interferometric observations of Circinus, building upon a recent $N$-band analysis. We used these observations to reconstruct images and fit Gaussian models to the $L$ and $M$ bands. Our findings reveal a thin edge-on disk whose width is marginally resolved and is the spectral continuation of the disk imaged in the $N$ band to shorter wavelengths. Additionally, we find a point-like source in the $L$ and $M$ bands that, based on the $LMN$-band spectral energy distribution fit, corresponds to the $N$-band point source. We also demonstrate that there is no trace of direct sightlines to hot dust surfaces in the circumnuclear dust structure of Circinus. By assuming the dust is present, we find that obscuration of A$_{\rm V} \gtrsim 250$ mag is necessary to reproduce the measured fluxes. Hence, the imaged disk could play the role of the obscuring "torus" in the unified scheme of active galactic nuclei. Furthermore, we explored the parameter space of the disk + hyperbolic cone radiative transfer models and identify a simple modification at the base of the cone. Adding a cluster of clumps just above the disk and inside the base of the hyperbolic cone provides a much better match to the observed temperature distribution in the central aperture. This aligns well with the radiation-driven fountain models that have recently emerged. Only the unique combination of sensitivity and spatial resolution of the VLTI allows such models to be scrutinized and constrained in detail. We plan to test the applicability of this detailed dust structure to other MATISSE-observed active galactic nuclei in the future.

astro-ph.GA↗

arXiv2023

A complex dust morphology in the high-luminosity AGN Mrk 876

Recent models for the inner structure of active galactic nuclei (AGN) advocate the presence of a radiatively accelerated, dusty outflow launched from the outer regions of the accretion disk. Here we present the first near-infrared (near-IR) variable (rms) spectrum for the high-luminosity, nearby AGN Mrk 876. We find that it tracks the accretion disk spectrum out to longer wavelengths than the mean spectrum due to a reduced dust emission. The implied outer accretion disk radius is consistent with the infrared results predicted by a contemporaneous optical accretion disk reverberation mapping campaign and much larger than the self-gravity radius. The reduced flux variability of the hot dust could be either due to the presence of a secondary, constant dust component in the mean spectrum or introduced by the destructive superposition of the dust and accretion disk variability signals or some combination of both. Assuming thermal equilibrium for optically thin dust, we derive the luminosity-based dust radius for different grain properties using our measurement of the temperature. We find that in all cases considered the values are significantly larger than the dust response time measured by IR photometric monitoring campaigns, with the least discrepancy present relative to the result for a wavelength-independent dust emissivity law, i.e. a blackbody, which is appropriate for large grain sizes. This result can be well explained by assuming a flared, disk-like structure for the hot dust.

astro-ph.GA↗

arXiv2022

The dusty heart of Circinus: I. Imaging the circumnuclear dust in N-band

Active galactic nuclei play a key role in the evolution of galaxies, but their inner workings and physical connection to the host are poorly understood due to a lack of angular resolution. Infrared interferometry makes it possible to resolve the circumnuclear dust in the nearby Seyfert 2 galaxy, Circinus. Previous observations have revealed complex structures and polar dust emission but interpretation was limited to simple models. MATISSE makes it possible to image these structures for the first time. We observed the Circinus Galaxy with VLTI/MATISSE, producing 150 correlated flux spectra and 100 closure phase spectra. We reconstructed images in the N-band at ~10 mas resolution. We fit blackbody functions with dust extinction to several aperture-extracted fluxes from the images to produce a temperature distribution of central dusty structures. We find significant substructure in the circumnuclear dust: central unresolved flux of ~0.5 Jy, a thin disk 1.9 pc in diameter oriented along ~45 deg,and a ~4x1.5 pc polar emission extending orthogonal to the disk. The polar emission exhibits patchiness, which we attribute to clumpy dust. Flux enhancements to the east and west of the disk are seen for the first time. We distinguish the temperature profiles of the disk and of the polar emission: the disk shows a steep temperature gradient indicative of denser material; the polar profile is flatter, indicating clumpiness and/or lower dust density. The unresolved flux is fitted with a high temperature, ~370 K. The polar dust remains warm (~200 K) out to 1.5 pc from the disk. The recovered morphology and temperature distribution resembles modeling of accretion disks with radiation-driven winds at large scales, but we placed new constraints on the subparsec dust. The subparsec features imaged here place new constraints on the physical modeling of circumnuclear dust in active galaxies.

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arXiv2021

P-REx II. Off-line Performance on VLTI/GRAVITY

For sensitive optical interferometry, it is crucial to control the evolution of the optical path difference (OPD) of the wavefront between the individual telescopes of the array. The OPD between a pair of telescopes is induced by differential optical properties such as atmospheric refraction, telescope alignment, etc. This has classically been measured using a fringe tracker that provides corrections to a piston actuator to account for this difference. An auxiliary method, known as the Piston Reconstruction Experiment (P-REx) has been developed to measure the OPD, or differential 'piston' of the wavefront, induced by the atmosphere at each telescope. Previously, this method was outlined and results obtained from LBT adaptive optics (AO) data for a single telescope aperture were presented. P-REx has now been applied off-line to previously acquired VLT's GRAVITY CIAO wavefront sensing data to estimate the atmospheric OPD for the six VLTI baselines. Comparisons with the OPD obtained from the VLTI GRAVITY fringe tracker were made. The results indicate that the telescope and instrumental noise of the combined VLTI and GRAVITY systems dominate over the atmospheric turbulence contributions. However, good agreement between simulated and on-sky P-REx data indicates that if the telescope and instrumental noise were reduced to atmospheric piston noise levels, P-REx has the potential to reduce the OPD root mean square of piston turbulence by up to a factor of 10 for frequencies down to 1 Hz. In such conditions, P-REx will assist in pushing the sensitivity limits of optical fringe tracking with long baseline interferometers.

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arXiv2021

Spatially Resolving the Kinematics of the $\lesssim 100\,μ$as Quasar Broad-line Region Using Spectroastrometry II. The First Tentative Detection in a Luminous Quasar at $z=2.3$

Direct measurements of the masses of supermassive black holes (SMBHs) are key to understanding their growth and constrain their symbiotic relationship to their host galaxies. However, current methods used to directly measure black hole masses in active quasars become challenging or impossible beyond $z\gtrsim0.2$. Spectroastrometry (SA) measures the spatial centroid of an object's spectrum as a function of wavelength, delivering angular resolution far better than the point-spread function (PSF) for high signal-to-noise ratio observations. We observed the luminous quasar SDSS J212329.47--005052.9 at $z=2.279$ with the aim of resolving its $\sim100μ\mathrm{as}$ H$α$ broad emission-line region (BLR), and present the first SA constraints on the size and kinematic structure of the BLR. Using a novel pipeline to extract the SA signal and reliable uncertainties, we achieved a centroiding precision of $\simeq100μ\mathrm{as}$, or $>2000\times$ smaller than the $K$-band AO-corrected PSF, yielding a tentative $3.2σ$ detection of an SA signal from the BLR. Modeling the BLR emission as arising from an inclined rotating disk with a mixture of coherent and random motions we constrain $r_\mathrm{BLR}=454^{+565}_{-162}\,μ\mathrm{as}$ ($3.71^{+4.65}_{-1.28}\,\mathrm{pc}$), providing a $95\%$ confidence upper limit on the black hole mass $M_\mathrm{BH}\,\sin^2\,i \leq1.8 \times10^9\,\mathrm{M}_\odot$. Our results agree with the $r_\mathrm{BLR}-L$ relation measured for lower-$z$ quasars, but expands its dynamic range by an order of magnitude in luminosity. We did not detect the potentially stronger SA signal from the narrow-line region, but discuss in detail why it may be absent. Already with existing instrumentation, SA can deliver $\sim6\times$ smaller uncertainties ($\sim15\,μ\mathrm{as}$) than achieved here, enabling $\sim10\%$ measurements of SMBH masses in high-$z$ quasars.

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arXiv2021

On-sky results for the novel integrated micro-lens ring tip-tilt sensor

We present the first on-sky results of the micro-lens ring tip-tilt (MLR-TT) sensor. This sensor utilizes a 3D printed micro-lens ring feeding six multi-mode fibers to sense misaligned light, allowing centroid reconstruction. A tip-tilt mirror allows the beam to be corrected, increasing the amount of light coupled into a centrally positioned single-mode (science) fiber. The sensor was tested with the iLocater acquisition camera at the Large Binocular Telescope in November 2019. The limit on the maximum achieved root mean square reconstruction accuracy was found to be 0.19 $λ$/D in both tip and tilt, of which approximately 50% of the power originates at frequencies below 10 Hz. We show the reconstruction accuracy is highly dependent on the estimated Strehl ratio and simulations support the assumption that residual adaptive optics aberrations are the main limit to the reconstruction accuracy. We conclude that this sensor is ideally suited to remove post-adaptive optics non-common path tip tilt residuals. We discuss the next steps for the concept development, including optimizations of the lens and fiber, tuning of the correction algorithm and selection of optimal science cases.

astro-ph.IM↗

arXiv2021

The Subarcsecond Mid-Infrared View of Local Active Galactic Nuclei. IV. The L- and M-band Imaging Atlas

We present the largest currently existing subarcsecond 3-5 $μ$m atlas of 119 local ($z < 0.3$) active galactic nuclei (AGN). This atlas includes AGN of 5 subtypes: 22 are Seyfert 1; 5 are intermediate Seyferts; 46 are Seyfert 2; 26 are LINERs; and 20 are composites/starbursts. Each AGN was observed with VLT ISAAC in the $L$- and/or $M$-bands between 2000 and 2013. We detect at 3$σ$ confidence 92 sources in the $L$-band and 83 sources in the $M$-band. We separate the flux into unresolved nuclear flux and resolved flux through two-Gaussian fitting. We report the nuclear flux, extended flux, apparent size, and position angle of each source, giving $3σ$ upper-limits for sources which are undetected. Using WISE W1- and W2-band photometry we derive relations predicting the nuclear $L$ and $M$ fluxes for Sy1 and Sy2 AGN based on their W1-W2 color and WISE fluxes. Lastly, we compare the measured mid-infrared colors to those predicted by dusty torus models SKIRTOR, CLUMPY, CAT3D, and CAT3D-WIND, finding best agreement with the latter. We find that models including polar winds best reproduce the 3-5$μ$m colors, indicating that winds are an important component of dusty torus models. We find that several AGN are bluer than models predict. We discuss several explanations for this and find that it is most plausibly stellar light contamination within the ISAAC $L$-band nuclear fluxes.

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arXiv2021

Hunting for intermediate-mass black holes in globular clusters: an astrometric study of NGC 6441

We present an astrometric study of the proper motions (PMs) in the core of the globular cluster NGC 6441. The core of this cluster has a high density and observations with current instrumentation are very challenging. We combine ground-based, high-angular-resolution NACO@VLT images with Hubble Space Telescope ACS/HRC data and measure PMs with a temporal baseline of 15 yr for about 1400 stars in the centermost 15 arcseconds of the cluster. We reach a PM precision of $\sim$30 $μ$as yr$^{-1}$ for bright, well-measured stars. Our results for the velocity dispersion are in good agreement with other studies and extend already-existing analyses of the stellar kinematics of NGC 6441 to its centermost region never probed before. In the innermost arcsecond of the cluster, we measure a velocity dispersion of (19.1 $\pm$ 2.0) km s$^{-1}$ for evolved stars. Because of its high mass, NGC 6441 is a promising candidate for harbouring an intermediate-mass black hole (IMBH). We combine our measurements with additional data from the literature and compute dynamical models of the cluster. We find an upper limit of $M_{\rm IMBH} < 1.32 \times 10^4\,\textrm{M}_\odot$ but we can neither confirm nor rule out its presence. We also refine the dynamical distance of the cluster to $12.74^{+0.16}_{-0.15}$ kpc. Although the hunt for an IMBH in NGC 6441 is not yet concluded, our results show how future observations with extremely-large telescopes will benefit from the long temporal baseline offered by existing high-angular-resolution data.

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arXiv2021

An innovative integral field unit upgrade with 3D-printed micro-lenses for the RHEA at Subaru

In the new era of Extremely Large Telescopes (ELTs) currently under construction, challenging requirements drive spectrograph designs towards techniques that efficiently use a facility's light collection power. Operating in the single-mode (SM) regime, close to the diffraction limit, reduces the footprint of the instrument compared to a conventional high-resolving power spectrograph. The custom built injection fiber system with 3D-printed micro-lenses on top of it for the replicable high-resolution exoplanet and asteroseismology spectrograph at Subaru in combination with extreme adaptive optics of SCExAO, proved its high efficiency in a lab environment, manifesting up to ~77% of the theoretical predicted performance.

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arXiv2020

The HOSTS survey for exozodiacal dust: Observational results from the complete survey

The Large Binocular Telescope Interferometer (LBTI) enables nulling interferometric observations across the N band (8 to 13 um) to suppress a star's bright light and probe for faint circumstellar emission. We present and statistically analyze the results from the LBTI/HOSTS (Hunt for Observable Signatures of Terrestrial Systems) survey for exozodiacal dust. By comparing our measurements to model predictions based on the Solar zodiacal dust in the N band, we estimate a 1 sigma median sensitivity of 23 zodis for early type stars and 48 zodis for Sun-like stars, where 1 zodi is the surface density of habitable zone (HZ) dust in the Solar system. Of the 38 stars observed, 10 show significant excess. A clear correlation of our detections with the presence of cold dust in the systems was found, but none with the stellar spectral type or age. The majority of Sun-like stars have relatively low HZ dust levels (best-fit median: 3 zodis, 1 sigma upper limit: 9 zodis, 95% confidence: 27 zodis based on our N band measurements), while ~20% are significantly more dusty. The Solar system's HZ dust content is consistent with being typical. Our median HZ dust level would not be a major limitation to the direct imaging search for Earth-like exoplanets, but more precise constraints are still required, in particular to evaluate the impact of exozodiacal dust for the spectroscopic characterization of imaged exo-Earth candidates.

astro-ph.SR↗

arXiv2019

Focal Plane Tip-Tilt Sensing for Improved Single-Mode Fiber Coupling using a 3D-printed Microlens-Ring

Modern extreme adaptive optics (AO) systems achieving diffraction-limited performance open up new possibilities for instrumentation. Especially important for the fields of spectroscopy and interferometry is that it enables the prospect to couple light into single-mode fibers (SMFs). However, due to their small size, efficient coupling is very sensitive to the quality of the fiber alignment, beam drifts and higher-frequency tip-tilt aberrations caused by telescope mechanics and vibrations. These residual aberrations are not always sensed and corrected by the AO system, leading to unacceptable losses. This is particularly severe for the Extremely Large Telescopes, where their huge structure will mean vibrations increase and optimal AO solutions are even more difficult to implement. We have created a focal plane sensor to correct for residual aberrations by surrounding the SMF with six Multi-mode fibers (MMFs). On each of the MMFs sits a printed freeform lens, making up a six-element micro-lens ring to refract the light into these surrounding MMFs and thus minimizing light loss in the gap between the fiber cores. This means when the beam is near diffraction limited and centered almost all light couples to the SMF. When the beam is misaligned, it couples to the surrounding cores, which are read out by a detector and processed by the DARC software driving a tip-tilt mirror. Currently we are aiming to detect and correct only tip-tilt aberrations. However, choosing to surround the central fiber with six sensing locations potentially allows us to investigate higher order correction modes. Here we present the design and performance our prototype system. This has been designed for use with the iLocater fiber injection system at the LBT and can easily be scaled to larger telescopes. We present test results from the KOOL laboratory and initial integration with the iLocater instrument.

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arXiv2019

SOWAT: Speckle Observations With Alleviated Turbulence

Adaptive optics (AO) systems and image reconstruction algorithms are indispensable tools when it comes to high-precision astrometry. In this paper, we analyze the potential of combining both techniques, i.e. by applying image reconstruction on partially AO corrected short exposures. Therefore we simulate speckle clouds with and without AO corrections and create synthetic observations. We apply holographic image reconstruction to the obtained observations and find that (i) the residual wavefronts decorrelate slowlier and to a lower limit when AO systems are used, (ii) the same reference stars yield a better reconstruction, and (iii) using fainter reference stars we achieve a similar image quality. These results suggest that holographic imaging of speckle observations is feasible with 2-3 times longer integration times and 3mag fainter reference stars, to obtain diffraction-limited imaging from low-order AO systems that are less restricted in sky-coverage than typical high-order AO systems.

astro-ph.IM↗

arXiv2018

Micro-lens array as tip-tilt sensor for single-mode fiber coupling

We introduce a design for a tip-tilt sensor with integrated single-mode fiber coupling for use with the front-end prototype of the iLocater spectrograph at the Large Binocular Telescope to detect vibrations that occur within the optical train. This sensor is made up of a micro-lens array printed on top of a fiber bundle consisting of a central single-mode fiber and six surrounding multi-mode fibers. The design in based on a previous prototype that utilized a multi-core fiber with seven single-mode fibers. With this updated design, we are able to achieve a better sensing throughput. We report on the modeled performance: if the beam is perfectly aligned, 69% light is coupled into the central single-mode fiber feeding the scientific instrument. When the beam is not aligned, some of the light will be coupled into the outer sensing fibers, providing the position of the beam for tip-tilt correction. For this design we show that there is a linear response in the sensing fibers when the beam is subject to tip-tilt movement. Furthermore we introduce an adaptive optics testbed, which we call the Koenigstuhl Observatory Opto-mechatronics Laboratory (KOOL), this testbed currently simulates vibrations at the Large Binocular Telescope, and in collaboration we have extended it to allow single-mode fiber coupling tests.

astro-ph.IM↗