Dr. Eloy Hernandez Profile

Dr. Eloy Hernandez

Postdoctoral researcher at Leibniz-Institut fur Astrophysik Potsdam

SPIE Involvement:

Author

Area of Expertise:

Photonics , Detectors , Optical fibres , NIR instrumentation , Numerical simulations

Publications (15)

Proceedings Article | 27 August 2024 Presentation + Paper

Assessment and removal of thin tearing resembling structures in deep-depletion CCDs

Eloy Hernandez, Javier Reyes, Olga Bellido-Tirado, Domingo Alvarez, Genoveva Micheva, Stella Vješnica, Roelof de Jong, Hakan Önel

Proceedings Volume 13103, 131030I (2024) https://doi.org/10.1117/12.3017636

KEYWORDS: Astronomical detectors, Detector development, Fluctuations and noise, Sensors, Charge-coupled devices, CCD image sensors, Spectrographs, Light emitting diodes, Ultraviolet light emitting diodes

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The 4-Metre Multi-Object Spectrograph Telescope (4MOST) is a second-generation instrument build for ESO’s VISTA telescope in Chile, enabling large-scale spectroscopic surveys of the night sky. 4MOST will complement several European space-based observatories and future ground-based survey facilities, furthering our understanding of the universe. The instrument uses over 2 400 science optical fibres to collect and transmit light simultaneously from various astronomical targets to three spectrographs. Two thirds of the fibres will go to low-resolutions spectrographs and the remaining to a high-resolution spectrograph. Each spectrograph has three channels. Each channel uses a charge-coupled device (CCD) 231-C6 from Teledyne e2v, which gives a total of 9 science detectors. The detectors have a resolution of 6k × 6k with a pixel size of 15 μm which accounts for a total image area of 92.2mm × 92.4 mm. The image area has four separately connected sections that allow the read-out to be conducted through four output circuits. The data acquisition and signal processing unit of each detector is a new general detector controller (NGC), which is a versatile platform for infrared and optical detectors developed by ESO that is already employed in several state-of-the-art instruments. During the testing phase of the different spectrographs, flat frames were acquired that showed an unidentified image structure manifesting mostly as diagonal lines across all quadrants with central-to-edge preferential pathways. The observed fingerprint showed a slightly elevated charge amount over a few pixels wide when compared to the rest of the array. Due to the dynamic variation of the affected pixels across successive frames, the feasibility of mitigating the described phenomenon through calibration was impractical. While large format CCDs of this nature find extensive application, and the NGC is a prevalent choice for ESO instrumentation, the observation of this particular artifact appears to be previously undocumented, although it shows some similarities with the tearing patterns observed in other deep-depletion devices which are associated with field distortions in thick silicon. In this work, we describe, evaluate, and present a removal technique for the undefined image structure observed in the science detectors of the 4MOST instrument.

Proceedings Article | 19 July 2024 Poster

Compact Arrayed Waveguide Stacked Multi-Object Spectrograph (CAWSMOS): design concept and preliminary results

Kalaga Madhav, Eloy Hernandez, Stella Vješnica, Alan Günther, Svend-Marian Bauer, Hakan Önel, Martin Roth

Proceedings Volume 13096, 13096A6 (2024) https://doi.org/10.1117/12.3020178

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Proceedings Article | 18 July 2024 Presentation + Paper

WST: Widefield Spectroscopic Telescope: addressing the instrumentation challenges of a new 12m class telescope dedicated to widefield multi-object and integral field spectroscopy

David Lee, Joël D. Vernet, Roland Bacon, Alexandre Jeanneau, Ernesto Oliva, Anna Brucalassi, Andrea Tozzi, José Araiza-Durán, Andrea Bianco, Jan Kragt, Ramon Navarro, Bianca Garilli, Kjetil Dohlen, Jean-Paul Kneib, Ricardo Araujo, Maxime Rombach, Eloy Hernandez, Roelof de Jong, Andreas Kelz, Stephen Watson, Tom Louth, Ian Bryson, Elizabeth George, Norbert Hubin, Julia Bryant, Jon Lawrence

Proceedings Volume 13096, 130960N (2024) https://doi.org/10.1117/12.3018257

KEYWORDS: Telescopes, Spectrographs, Design, Spectroscopes, Mirrors, CMOS sensors, Sensors, Optical design

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Proceedings Article | 18 July 2024 Presentation + Paper

Preliminary results of the Potsdam Arrayed Waveguide Spectrograph

Eloy Hernandez, Alan Günther, Stella Vješnica, Svend-Marian Bauer, Andreas Stoll, Hakan Önel, Kalaga Madhav, Martin Roth

Proceedings Volume 13096, 130960L (2024) https://doi.org/10.1117/12.3018014

KEYWORDS: Arrayed waveguide gratings, Sensors, Waveguides, Spectrographs, Cryostats, Near infrared spectroscopy, Astrophotonics, Frequency combs

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Arrayed waveguide gratings (AWG) have gained attention as promising integrated spectrographs for ground-based telescopes, airborne applications, and spaceborne instrumentation due to their low mass, diffraction limit characteristics, thermal stability, and robustness against vibrations and misalignment. The Potsdam Arrayed Waveguide Spectrograph (PAWS) is a cross-dispersive instrument based on an integrated photonic spectrograph (IPS) that is optimized for the astronomical H-Band and was designed and developed by innoFSPEC at the Leibniz Institute for Astrophysics Potsdam (AIP). The main element is a second-generation AWG that is fibre coupled and works as a first dispersive element. To work as an IPS, the dispersed light of the AWG is sampled at the output facet and magnified by a microscope objective. The light is then fed into a free-space optical system housed in a cryostat working at 140 K. An afocal relay re-images the exit pupil of the microscope into the plane of a cross-dispersive element containing a diffractive grating. Subsequently, an objective focuses the resulting echellogram on a Teledyne 2k × 2k H2RG near-infrared array working at 80 K. To validate the functionality of the system, different light sources have been used. A tunable laser source generated an echellogram through frame stacking. Furthermore, the cross-dispersed output of a supercontinuum source and of an in-house developed frequency comb system were recorded under varying input conditions of the AWG, successfully achieving first light laboratory measurements. Throughout multiple cycles and measurements of the instrument, several parameters and characteristics were identified, providing opportunities for optimization to enhance the instrument’s performance and facilitate the miniaturization of future iterations. In this manuscript, we will provide a concise overview of the PAWS instrument, the preliminary results of laboratory measurements, and lessons learned to improve the future iterations of the next generation near-infrared cross-dispersed integrated photonic spectrograph. PAWS represents a pioneering demonstration of an astronomy optimized AWG chip, showcasing the advantageous capabilities of integrated photonic spectrograph.

Proceedings Article | 17 March 2023 Presentation + Paper

Astrophotonics: photonic integrated circuits for astronomical instrumentation

Martin Roth, Kalaga Madhav, Andreas Stoll, Daniel Bodenmüller, Aline Dinkelaker, Aashia Rahman, Eloy Hernandez, Alan Günther, Stella Vjesnica

Proceedings Volume 12424, 124240B (2023) https://doi.org/10.1117/12.2655630

KEYWORDS: Arrayed waveguide gratings, Waveguides, Astronomy, Spectrographs, Photonic integrated circuits, Frequency combs, Telescopes, Spectral resolution, Design and modelling, Beam combiners

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Proceedings Article | 29 August 2022 Poster + Paper

The BlueMUSE calibration unit: phase-A studies

Martin Roth, Peter Weilbacher, Andreas Kelz, Kalaga Madhav, Eloy Hernandez, Johan Richard, Rémy Giroud, Roland Bacon

Proceedings Volume 12184, 121845S (2022) https://doi.org/10.1117/12.2629630

KEYWORDS: Calibration, Lamps, Fabry–Perot interferometers, Spectrographs, Frequency combs, Velocity measurements, Telescopes

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Proceedings Article | 29 August 2022 Presentation + Paper

System integration of the Potsdam Arrayed Waveguide Spectrograph (PAWS)

Eloy Hernandez, Alan Günther, Svend-Marian Bauer, Christian Dani Guzmán, Christer Sandin, Andreas Stoll, Stella Vjesnica, Kalaga Madhav, Martin M. Roth

Proceedings Volume 12184, 121841O (2022) https://doi.org/10.1117/12.2627318

KEYWORDS: Sensors, Temperature metrology, Cryocoolers, Cryogenics, Bridges, Computer aided design, Molybdenum, Spectrographs, Mirrors, Electronics

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Proceedings Article | 26 August 2022 Poster + Paper

On-sky experiment of the discrete beam combiner: lessons learned and strategies for improved calibration of the transfer function

Abani Shankar Nayak, Lucas Labadie, Tarun Sharma, Simone Piacentini, Giacomo Corrielli, Roberto Osellame, Ettore Pedretti, Aline Dinkelaker, Eloy Hernandez, Kalaga Madhav, Martin Roth

Proceedings Volume 12183, 121832H (2022) https://doi.org/10.1117/12.2629673

KEYWORDS: Visibility, Waveguides, Cameras, Sensors, Photometry, Calibration, Telescopes, Photodetectors, Interferometry, Integrated optics

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Proceedings Article | 13 December 2020 Poster + Presentation + Paper

Optomechanical design of PAWS, the Potsdam Arrayed Waveguide Spectrograph

Eloy Hernandez, Andreas Stoll, Svend-Marian Bauer, Amokrane Berdja, Rafael Bernardi, Dani Guzman, Alan Günther, Kalaga Madhav, Martin Roth, Christer Sandin, Constanza Villanueva

Proceedings Volume 11451, 114515O (2020) https://doi.org/10.1117/12.2562174

KEYWORDS: Waveguides, Spectrographs, Single mode fibers, Optical design, Telescopes, Calibration, Microscopes, Free space optics, Integrated photonics, Astronomy

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Proceedings Article | 6 January 2020 Paper

PRAXIS: an OH suppression optimised near infrared spectrograph

S. Ellis, J. Bland-Hawthorn, S. Bauer, S. Case, R. Content, T. Fechner, D. Giannone, R. Haynes, E. Hernandez, A. Horton, U. Klauser, J. Lawrence, S. Leon-Saval, H.-G. Löhmannsröben, S.-S. Min, N. Pai, M. Roth, L. Waller, R. Zhelem

Proceedings Volume 11203, 1120312 (2020) https://doi.org/10.1117/12.2539883

KEYWORDS: Near infrared, Spectrographs, Bragg gratings, Near infrared spectroscopy, Astronomical imaging

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Proceedings Article | 10 July 2018 Paper

Analysis of mode excitation on different geometries of optical fibres for astronomical spectroscopy

Eloy Hernandez, Martin Roth, Andreas Kelz

Proceedings Volume 10705, 107051K (2018) https://doi.org/10.1117/12.2312487

KEYWORDS: Optical fibers, Refractive index, Fourier transforms, Wave propagation, Multimode fibers, Astronomical spectroscopy, Geometrical optics, Cladding, Astrophysics

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Proceedings Article | 6 July 2018 Presentation + Paper

PRAXIS: an OH suppression optimised near infrared spectrograph

S. Ellis, S. Bauer, C. Bacigalupo, J. Bland-Hawthorn, J. Bryant, S. Case, R. Content, T. Fechner, D. Giannone, R. Haynes, E. Hernandez, A. Horton, U. Klauser, J. Lawrence, S. Leon-Saval, E. Lindley, H.-G. Löhmannsröben, S.-S. Min, N. Pai, M. Roth, K. Shortridge, L. Waller, Pascal Xavier, Ross Zhelem

Proceedings Volume 10702, 107020P (2018) https://doi.org/10.1117/12.2311898

KEYWORDS: Spectrographs, Bragg gratings, Fiber Bragg gratings, Telescopes, Near infrared, Diffraction gratings, Optical design, Near infrared spectroscopy, Optical filters

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Proceedings Article | 9 August 2016 Paper

PRAXIS: a near infrared spectrograph optimised for OH suppression

S. Ellis, S. Bauer, J. Bland-Hawthorn, S. Case, R. Content, T. Fechner, D. Giannone, R. Haynes, E. Hernandez, A. Horton, U. Klauser, J. Lawrence, S. Leon-Saval, E. Lindley, H.-G. Löhmannsröben, S.-S. Min, N. Pai, M. Roth, K. Shortridge, Nicholas Staszak, Julia Tims, Pascal Xavier, Ross Zhelem

Proceedings Volume 9908, 99084A (2016) https://doi.org/10.1117/12.2232115

KEYWORDS: Fiber Bragg gratings, Spectrographs, Sensors, Near infrared, Astronomy, Fiber Bragg gratings, Near infrared, Optical design, Telescopes, Near infrared spectroscopy, Metrology, Spectroscopes

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Proceedings Article | 4 August 2016 Paper

Model-based calculations of fiber output fields for fiber-based spectroscopy

Eloy Hernandez, Daniel Bodenmüller, Martin Roth, Andreas Kelz

Proceedings Volume 9907, 990734 (2016) https://doi.org/10.1117/12.2232401

KEYWORDS: Spectroscopy, Spectroscopy, Spectrographs, Point spread functions, Astronomy, Wave propagation, Astronomical imaging, Process modeling, Refractive index, Finite element methods, Telescopes

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Proceedings Article | 28 July 2014 Paper

Astronomical optical frequency comb generation and test in a fiber-fed MUSE spectrograph

J. Chavez Boggio, T. Fremberg, B. Moralejo, M. Rutowska, E. Hernandez, M. Zajnulina, A. Kelz, D. Bodenmüller, C. Sandin, M. Wysmolek, H. Sayinc, J. Neumann, R. Haynes, M. Roth

Proceedings Volume 9151, 915120 (2014) https://doi.org/10.1117/12.2056684

KEYWORDS: Spectrographs, Optical fibers, Frequency combs, Astronomy, Calibration, Astronomical imaging, Lamps, Neon, Optical filters, Nonlinear crystals

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Showing 5 of 15 publications

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