arXiv subjects

Peter Bizenberger

Publications and source records attributed to Peter Bizenberger.

9 recordsLinked to original sources

arXiv2026

Development of an adaptive optics testbed at MPIA for the ELT/Planetary Camera and Spectrograph (PCS)

The Planetary Camera and Spectrograph (PCS) is a proposed second-generation instrument for the Extremely Large Telescope (ELT), dedicated to the direct imaging and characterization of exoplanets. To meet its demanding science requirements, PCS will incorporate an extreme adaptive optics (AO) system, building upon the heritage of existing ELT AO instruments such as ELT/METIS, as well as high-contrast AO systems at the ELT and the VLT, including SPHERE and its upcoming upgrade, SAXO+. PCS development requires extensive research and development to advance critical AO technologies. In this work, we present the Max Planck Institute for Astronomy (MPIA) plan for a modular testbed to validate key components and control strategies. This testbed will integrate two deformable mirrors, including a DM prototype developed by Bertin-ALPAO in collaboration with ESO, with an estimated delivery in 2029. The facility will enable testing of different Fourier filtering wavefront sensors, including novel mask designs, while exploring different control architectures, such as woofer-tweeter configurations with a single wavefront sensor for both deformable mirrors or fully independent AO stages. Additionally, the testbed will leverage MPIA's expertise in real-time computer development to experiment with advanced control strategies, including predictive control and machine learning-enhanced AO techniques. This contribution presents the current status of PCS development at MPIA, highlighting the ongoing R\&D efforts to mature its AO system for high-contrast imaging with the ELT.

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arXiv2026

Charge migration characterization in the METIS H2RG detectors

The Mid-infrared ELT Imager and Spectrograph (METIS) is one of the first-light instruments of the Extremely Large Telescope (ELT). For the L and M band, the instrument makes use of Teledyne's H2RG detectors, known to be affected by charge migration, also known as the brighter-fatter effect (BFE). In the H2RG detectors this manifests as photo-electrons moving from a central bright pixel to neighboring pixels as the depletion region of the central pixel shrinks with accumulated charge. Due to its effect of `blurring' information, it especially affects direct imaging, transit, and high-resolution spectroscopy applications. We aim to characterize its effect in the METIS H2RG detectors, such that we can remove it without losing information.

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arXiv2026

Assembly, integration, and verification of MITESI: an optical testbed for simulating the ELT in the laboratory

MITESI is an optical testbed which simulates key characteristics of the ELT, ultimately producing an artificial natural guide star. It was designed primarily to enable testing of the METIS instrument's SCAO system in closed loop. In this contribution, we discuss the assembly, integration and verification process of the testbed, taking the project from design to assembled hardware.

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arXiv2022

Validating the Local Volume Mapper acquisition and guiding hardware

The Local Volume Mapper (LVM) project is one of three surveys that form the Sloan Digital Sky Survey V. It will map the interstellar gas emission in a large fraction of the southern sky using wide-field integral field spectroscopy. Four 16-cm telescopes in siderostat configuration feed the integral field units (IFUs). A reliable acquisition and guiding (A&G) strategy will help ensure that we meet our science goals. Each of the telescopes hosts commercial CMOS cameras used for A&G. In this work, we present our validation of the camera performance. Our tests show that the cameras have a readout noise of around 5.6e- and a dark current of 21e-/s, when operated at the ideal gain setting and at an ambient temperature of 20{\deg}C. To ensure their performance at a high-altitude observing site, such as the Las Campanas Observatory, we studied the thermal behaviour of the cameras at different ambient pressures and with different passive cooling solutions. Using the measured properties, we calculated the brightness limit for guiding exposures. With a 5 s exposure time, we reach a depth of around 16.5 Gaia gmag with a signal-to-noise ratio (SNR)>5. Using Gaia Early Data Release 3, we verified that there are sufficient guide stars for each of the around 25000 survey pointings. For accurate acquisition, we also need to know the focal plane geometry. We present an approach that combines on-chip astrometry and using a point source microscope to measure the relative positions of the IFU lenslets and the individual CMOS pixels to around 2 $\mu$m accuracy.

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arXiv2020

Infrared wavefront sensing for adaptive optics assisted Galactic Center observations with the VLT interferometer and GRAVITY: operation and results

This article describes the operation of the near-infrared wavefront sensing based Adaptive Optics (AO) system CIAO. The Coudé Infrared Adaptive Optics (CIAO) system is a central auxiliary component of the Very Large Telescope (VLT) interferometer (VLTI). It enables in particular the observations of the Galactic Center (GC) using the GRAVITY instrument. GRAVITY is a highly specialized beam combiner, a device that coherently combines the light of the four 8-m telescopes and finally records interferometric measurements in the K-band on 6 baselines simultaneously. CIAO compensates for phase disturbances caused by atmospheric turbulence, which all four 8 m Unit Telescopes (UT) experience during observation. Each of the four CIAO units generates an almost diffraction-limited image quality at its UT, which ensures that maximum flux of the observed stellar object enters the fibers of the GRAVITY beam combiner. We present CIAO performance data obtained in the first 3 years of operation as a function of weather conditions. We describe how CIAO is configured and used for observations with GRAVITY. In addition, we focus on the outstanding features of the near-infrared sensitive Saphira detector, which is used for the first time on Paranal, and show how it works as a wavefront sensor detector.

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arXiv2019

Development of the Warm Astrometric Mask for MICADO astrometry calibration

The achievement of $μ$arcsec relative astrometry with ground-based, near infrared, extremely large telescopes requires a significant endeavour of calibration strategies. In this paper we address the removal of instrument optical distortions coming from the ELT first light instrument MICADO and its adaptive optics system MAORY by means of an astrometric calibration mask. The results of the test campaign on a prototype mask (scale 1:2) has probed the manufacturing precision down to $\sim$ 50nm/1mm scale, leading to a relative precision $δσ\sim 5e-5$. The assessed manufacturing precision indicates that an astrometric relative precision of $δσ\sim 5e-5 = \frac{50μas}{1 arcsec}$ is in principle achievable, disclosing $μ$arcsec near infrared astrometry behind an extremely large telescope. The impact of $\sim$ 10-100 nm error residuals on the mask pinholes position is tolerable at a calibration level as confirmed by ray tracing simulations of realistic MICADO distortion patterns affected by mid spatial frequencies residuals. We demonstrated that the MICADO astrometric precision of 50 $μ$as is achievable also in presence of a mid spatial frequencies pattern and manufacturing errors of the WAM by fitting the distorted WAM pattern seen through the instrument with a 10$^{th}$ order Legendre polynomial.

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arXiv2018

The MICADO first light imager for the ELT: overview, operation, simulation

MICADO will enable the ELT to perform diffraction limited near-infrared observations at first light. The instrument's capabilities focus on imaging (including astrometric and high contrast) as well as single object spectroscopy. This contribution looks at how requirements from the observing modes have driven the instrument design and functionality. Using examples from specific science cases, and making use of the data simulation tool, an outline is presented of what we can expect the instrument to achieve.

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arXiv2014

Laboratory Results and Status Update for Pathfinder at LBT, The LINC-NIRVANA NGS Ground- Layer AO Subsystem

The full LINC-NIRVANA instrument will be one of the most complex ground-based astronomical systems ever built. It will consist of multiple subsystems, including two multi-conjugate ground layer AO systems (MCAO) that drive the LBT adaptive secondaries, two mid-high layer AO systems with their own Xynetics 349 actuator DM's , a fringe tracker, a beam combiner, and the NIR science camera. In order to mitigate risk, we take a modular approach to instrument testing and commissioning by decoupling these subsystems individually. The first subsystem tested on-sky will be one of the ground-layer AO systems, part of a test-bed known as the Pathfinder. The Pathfinder consists of a 12-star pyramid wavefront sensor (PWFS) that drives one of the LBT's adaptive secondaries, a support structure known as "The Foot," and the infrared test camera (IRTC), which is used for acquisition and alignment. The 12 natural guide stars are acquired by moveable arms called "star enlargers," each of which contains its own optical path. The Pathfinder was shipped from MPIA in Heidelberg, Germany to the LBT mountain lab on Mt. Graham, Arizona in February 2013. The system was unpacked, assembled in the LBT clean room, and internally optically aligned. We present the results of our system tests, including star enlarger alignment and system alignment. We also present our immediate plans for on-sky closed loop tests on the LBT scheduled for late Fall. Because plans for all ELTs call for ground layer correction, the Pathfinder provides valuable preliminary information not only for the full LINC-NIRVANA system, but also for future advanced MCAO systems.

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arXiv2000

Achieving a wide field near infrared camera for the Calar Alto 3.5m telescope

The ongoing development of large infrared array detectors has enabled wide field, deep surveys to be undertaken. There are, however, a number of challenges in building an infrared instrument which has both excellent optical quality and high sensitivity over a wide field. We discuss these problems in the context of building a wide field imaging camera for the 3.5m telescope at Calar Alto with the new 2K*2K HgCdTe HAWAII-2 focal plane array. Our final design is a prime focus camera with a 15' field-of-view, called Omega 2000. To achieve excellent optical quality over the whole field, we have had to dispense with the reimaging optics and cold Lyot stop. We show that creative baffling schemes, including the use of undersized baffles, can compensate for the lost K band sensitivity. A moving baffle will be employed in Omega 2000 to allow full transmission in the non-thermal J and H bands.

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