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Pre-distortion adaptive optics for optical feeder links: simulations and performance analyses (2024)
Journal Article
Hristovski, I. R., Osborn, J., Farley, O. J. D., Townson, M. J., Calvo, R. M., Femenía-Castella, B., …Reeves, A. P. (2024). Pre-distortion adaptive optics for optical feeder links: simulations and performance analyses. Optics Express, 32(12), 20976-20991. https://doi.org/10.1364/oe.521494

Optical feeder links offer immense utility in meeting future communication demands—however, atmospheric turbulence limits their performance. This work targets this challenge through analyses of a bidirectional free-space optical communication (FSOC)... Read More about Pre-distortion adaptive optics for optical feeder links: simulations and performance analyses.

Exploring atmospheric optical turbulence: observations across zenith angles (2024)
Journal Article
Beesley, L. F., Osborn, J., Wilson, R., Farley, O. J. D., Griffiths, R., & Love, G. D. (2024). Exploring atmospheric optical turbulence: observations across zenith angles. Applied Optics, 63(16), E48. https://doi.org/10.1364/ao.519063

We present measurements of the atmospheric optical turbulence as a function of zenith angle using two identical instruments, Shack-Hartmann Image Motion Monitors (SHIMMs), to measure atmospheric parameters concurrently. One instrument was pointed nea... Read More about Exploring atmospheric optical turbulence: observations across zenith angles.

A comparison of next-generation turbulence profiling instruments at Paranal (2024)
Journal Article
Griffiths, R., Bardou, L., Butterley, T., Osborn, J., Wilson, R., Bustos, E., …Otarola, A. (2024). A comparison of next-generation turbulence profiling instruments at Paranal. Monthly Notices of the Royal Astronomical Society, 529(1), 320 - 330. https://doi.org/10.1093/mnras/stae434

A six-night optical turbulence monitoring campaign has been carried at Cerro Paranal observatory in February and March, 2023 to facilitate the development and characterisation of two novel atmospheric site monitoring instruments - the ring-image next... Read More about A comparison of next-generation turbulence profiling instruments at Paranal.

Continuous daytime and nighttime forecast of atmospheric optical turbulence from numerical weather prediction models (2023)
Journal Article
Quatresooz, F., Griffiths, R., Bardou, L., Wilson, R., Osborn, J., Vanhoenacker-Janvier, D., & Oestges, C. (2023). Continuous daytime and nighttime forecast of atmospheric optical turbulence from numerical weather prediction models. Optics Express, 31(21), 33850-33872. https://doi.org/10.1364/oe.500090

Future satellite-to-ground optical communication systems will benefit from accurate forecasts of atmospheric optical turbulence; namely for site selection, for the routing and the operation of optical links, and for the design of optical communicatio... Read More about Continuous daytime and nighttime forecast of atmospheric optical turbulence from numerical weather prediction models.

Optical sparse telescope arrays and scintillation noise (2023)
Journal Article
Hartley, K. E., Farley, O. J. D., Townson, M. J., Osborn, J., & Wilson, R. W. (2023). Optical sparse telescope arrays and scintillation noise. Monthly Notices of the Royal Astronomical Society, 526(1), 1235-1245. https://doi.org/10.1093/mnras/stad2835

Fresnel propagation of starlight after it passes through high altitude turbulence in the Earth’s atmosphere results in random fluctuations of the intensity at ground level, known as scintillation. This effect adds random noise to photometric measurem... Read More about Optical sparse telescope arrays and scintillation noise.

Line-of-sight optical Dome Turbulence Monitor (2023)
Journal Article
Osborn, J., & Alaluf, D. (2023). Line-of-sight optical Dome Turbulence Monitor. Monthly Notices of the Royal Astronomical Society, 525(2), 1936-1940. https://doi.org/10.1093/mnras/stad2428

Optical turbulence in the enclosure of a ground-based telescope can be a major contributor to the total optical turbulence strength and can therefore limit the precision of astronomical observations, in terms of angular resolution, or signal to noise... Read More about Line-of-sight optical Dome Turbulence Monitor.

The 24hSHIMM: a continuous day and night turbulence monitor for optical communications (2023)
Conference Proceeding
Griffiths, R., Osborn, J., Farley, O., Butterley, T., Townson, M., & Wilson, R. (2023). The 24hSHIMM: a continuous day and night turbulence monitor for optical communications. In H. Hemmati, & B. S. Robinson (Eds.), Proceedings Volume 12413, Free-Space Laser Communications XXXV. https://doi.org/10.1117/12.2648789

We present the 24-hour Shack-Hartmann Image Motion Monitor (24hSHIMM), the first truly continuous, 24-hour optical turbulence monitor. Atmospheric optical turbulence is a significant limitation for free-space optical communications and other technolo... Read More about The 24hSHIMM: a continuous day and night turbulence monitor for optical communications.

First On-Sky Demonstration of a Scintillation Correction technique using Tomographic Wavefront Sensing (2023)
Journal Article

Scintillation noise significantly limits high precision ground-based photometry of bright stars. In this paper we present the first ever on-sky demonstration of scintillation correction. The technique uses tomographic wavefront sensing to estimate th... Read More about First On-Sky Demonstration of a Scintillation Correction technique using Tomographic Wavefront Sensing.

Atmospheric optical turbulence measurements at varying elevation angles (2023)
Presentation / Conference
Westerby-Griffin, L., Osborn, J., Farley, O. J. D., Griffiths, R., & Love, G. D. (2023, January). Atmospheric optical turbulence measurements at varying elevation angles. Paper presented at Free-Space Laser Communications XXXV, San Francisco, United States

FAST: Fourier domain adaptive optics simulation tool for bidirectional ground-space optical links through atmospheric turbulence (2022)
Journal Article

Free space optical links between the ground and space may be severely degraded by atmospheric turbulence. Adaptive Optics, a technique allowing partial correction of this degradation, is beginning to see use in the field with the potential to achieve... Read More about FAST: Fourier domain adaptive optics simulation tool for bidirectional ground-space optical links through atmospheric turbulence.

First stellar photons for an integrated optics discrete beam combiner at the William Herschel Telescope (2021)
Journal Article

We present the first on-sky results of a four-telescope integrated optics discrete beam combiner (DBC) tested at the 4.2 m William Herschel Telescope. The device consists of a four-input pupil remapper followed by a DBC and a 23-output reformatter. T... Read More about First stellar photons for an integrated optics discrete beam combiner at the William Herschel Telescope.

Correction of finite spatial and temporal sampling effects in stereo-SCIDAR (2020)
Conference Proceeding
Butterley, T., Sarazin, M., Le Louarn, M., Osborn, J., & Farley, O. J. (2020). Correction of finite spatial and temporal sampling effects in stereo-SCIDAR. . https://doi.org/10.1117/12.2562559

Stereo scintillation detection and ranging (S-SCIDAR) is a development of the well-established SCIDAR turbulence profiling technique. An S-SCIDAR instrument has been installed at the focus of one of the 1.8m Auxiliary Telescopes at Paranal observator... Read More about Correction of finite spatial and temporal sampling effects in stereo-SCIDAR.

Mesoscale modelling of optical turbulence in the atmosphere: the need for ultrahigh vertical grid resolution (2020)
Journal Article

The high-fidelity modelling of optical turbulence is critical to the design and operation of a new class of emerging highly sophisticated astronomical telescopes and adaptive optics instrumentation. In this study, we perform retrospective simulations... Read More about Mesoscale modelling of optical turbulence in the atmosphere: the need for ultrahigh vertical grid resolution.

Limitations imposed by optical turbulence profile structure and evolution on tomographic reconstruction for the ELT (2020)
Journal Article

The performance of tomographic adaptive optics (AO) systems is intrinsically linked to the vertical profile of optical turbulence. First, a sufficient number of discrete turbulent layers must be reconstructed to model the true continuous turbulence p... Read More about Limitations imposed by optical turbulence profile structure and evolution on tomographic reconstruction for the ELT.

Optimizing the accuracy and efficiency of optical turbulence profiling using adaptive optics telemetry for extremely large telescopes (2018)
Journal Article

Advanced adaptive optics (AO) instruments on ground-based telescopes require accurate knowledge of the atmospheric turbulence strength as a function of altitude. This information assists point spread function reconstruction, AO temporal control techn... Read More about Optimizing the accuracy and efficiency of optical turbulence profiling using adaptive optics telemetry for extremely large telescopes.

Modelling synthetic atmospheric turbulence profiles with temporal variation using Gaussian mixture model (2018)
Journal Article

The atmospheric turbulence profile plays a very important role for performance evaluation of wide-field adaptive optic systems. Since the atmospheric turbulence is evolving, the turbulence profile will change with time. To better model the temporal v... Read More about Modelling synthetic atmospheric turbulence profiles with temporal variation using Gaussian mixture model.

On-sky demonstration of matched filters for wavefront measurements using ELT-scale elongated laser guide stars (2017)
Journal Article

The performance of adaptive optics systems is partially dependent on the algorithms used within the real-time control system to compute wavefront slope measurements. We demonstrate the use of a matched filter algorithm for the processing of elongated... Read More about On-sky demonstration of matched filters for wavefront measurements using ELT-scale elongated laser guide stars.

Photometry and Spectrum measurements of the Laser Guide Star beam emission at Observatorio del Roque de Los Muchachos with the Gran Telescope Canarias (2017)
Presentation / Conference Contribution

In the past years ESO has built together with industry a transportable Laser Guide Star Unit (WLGSU) to test the laser technology while supporting some strategic experiments for the LGS-AO technologies. Since July 2016, the WLGSU has been installed a... Read More about Photometry and Spectrum measurements of the Laser Guide Star beam emission at Observatorio del Roque de Los Muchachos with the Gran Telescope Canarias.

Turbulence velocity profiling for high sensitivity and vertical-resolution atmospheric characterization with Stereo-SCIDAR (2016)
Journal Article

As telescopes become larger, into the era of ∼40 m Extremely Large Telescopes, the high-resolution vertical profile of the optical turbulence strength is critical for the validation, optimization and operation of optical systems. The velocity of atmo... Read More about Turbulence velocity profiling for high sensitivity and vertical-resolution atmospheric characterization with Stereo-SCIDAR.

Experience with wavefront sensor and deformable mirror interfaces for wide-field adaptive optics systems (2016)
Journal Article

Recent advances in adaptive optics (AO) have led to the implementation of wide field-of-view AO systems. A number of wide-field AO systems are also planned for the forthcoming Extremely Large Telescopes. Such systems have multiple wavefront sensors o... Read More about Experience with wavefront sensor and deformable mirror interfaces for wide-field adaptive optics systems.

Scintillation correction for astronomical photometry on large and extremely large telescopes with tomographic atmospheric reconstruction (2014)
Journal Article

We describe a new concept to correct for scintillation noise on high-precision photometry in large and extremely large telescopes using telemetry data from adaptive optics (AO) systems. Most wide-field AO systems designed for the current era of very... Read More about Scintillation correction for astronomical photometry on large and extremely large telescopes with tomographic atmospheric reconstruction.

Atmospheric optical turbulence analysis in London’s financial district
Conference Proceeding
Westerby-Griffin, L., Osborn, J., Farley, O. J. D., Griffiths, R., & Love, G. D. (2023). Atmospheric optical turbulence analysis in London’s financial district. In H. Hemmati, & B. S. Robinson (Eds.), Proceedings Volume 12413, Free-Space Laser Communications XXXV. https://doi.org/10.1117/12.2648907

Atmospheric optical turbulence causes signal loses in laser propagation. Here we present vertical measurements of optical turbulence taken in London’s financial district. Additionally, we demonstrate a method of modelling atmospheric states in simula... Read More about Atmospheric optical turbulence analysis in London’s financial district.