Hot-air optical turbulence generator for the testing of adaptive optics systems: principles and characterization

2006 ◽  
Vol 45 (20) ◽  
pp. 4888 ◽  
Author(s):  
Onur Keskin ◽  
Laurent Jolissaint ◽  
Colin Bradley
Keyword(s):  
Adaptive Optics ◽  
Optical Turbulence ◽  
Hot Air ◽  
Turbulence Generator

Hot-air turbulence generator for multiconjugate adaptive optics

2003 ◽  
Author(s):  
Onur Keskin ◽  
Laurent Jolissaint ◽  
Colin Bradley ◽  
Sadik Dost ◽  
Inna Sharf
Keyword(s):  
Adaptive Optics ◽  
Hot Air ◽  
Air Turbulence ◽  
Turbulence Generator

Multiple-layer optical turbulence generator principle and SLODAR characterization: preliminary results

2004 ◽  
Author(s):  
Laurent Jolissaint ◽  
Onur Keskin ◽  
Colin Bradley ◽  
Brian Wallace ◽  
Aaron Hilton
Keyword(s):  
Optical Turbulence ◽  
Preliminary Results ◽  
Multiple Layer ◽  
Turbulence Generator

scholarly journals Forecasting seeing for the Maunakea Observatories

2020 ◽  
Vol 496 (4) ◽  
pp. 4734-4748
Author(s):  
Ryan Lyman ◽  
Tiziana Cherubini ◽  
Steven Businger
Keyword(s):  
Adaptive Optics ◽  
Atmospheric Stability ◽  
Weather Conditions ◽  
Image Resolution ◽  
Image Motion ◽  
Optical Turbulence ◽  
Observational Measures ◽  
Weather Model ◽  
Operational Forecasting

ABSTRACT Optical turbulence greatly impacts the range and quality of astronomical observations. Advanced knowledge of the expected atmospheric optical turbulence provides important guidance that helps astronomers decide which instrument to schedule and enables them to optimize the adaptive optics technology that improves image resolution. Along with forecasts of weather conditions, prediction of the optical observing quality on the Maunakea summit has been a goal for the Maunakea Weather Center (MKWC) since its inception more than 20 yr ago. Forecasting optical turbulence, and its derivative, ‘seeing’, has proven to be quite challenging because optical turbulence is too small and complex to directly capture with a regional weather model. Fortunately, the permanent installation of a Differential Image Motion Monitor (DIMM) and Multi-Aperture Scintillation Sensor (MASS) at the summit of Maunakea has made seeing observations available during the last decade, providing valuable feedback to the MKWC. This paper summarizes the experience at MKWC in anticipating optical turbulence for the summit of Maunakea accrued through years of daily operational forecasting, and continuous comparison between MKWC official forecasts, model guidance, and observational measures of seeing. Access to a decade seeing observations has allowed quantification the factors that impact seeing, including wind shear, atmospheric stability patterns, and optical turbulence, and to document the seasonal and intra-seasonal variations in seeing. Consequently, the combination of experience gained, and custom model guidance has led to more accurate seeing forecasts (rms errors averaging <0.25 arcsec since 2012) for the Maunakea astronomical observatories.

scholarly journals Atmospheric Characterization Based on Relative Humidity Control at Optical Turbulence Generator

Atmosphere ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 550
Author(s):  
Jhonny Villamizar ◽  
Manuel Herreño ◽  
Omar Tíjaro ◽  
Yezid Torres
Keyword(s):  
Relative Humidity ◽  
Laser Beam ◽  
Optical Axis ◽  
Optical Turbulence ◽  
Air Velocity ◽  
Limited Effect ◽  
Horizontal Path ◽  
Physical Variables ◽  
Turbulence Parameters ◽  
Turbulence Generator

In atmospheric turbulence, relative humidity has been almost a negligible variable due to its limited effect, compared with temperature and air velocity, among others. For studying the horizontal path, a laser beam was propagated in a laboratory room, and an Optical Turbulence Generator (OTG) was built and placed along the optical axis. Additionally, there was controlled humidity inside the room and measuring of some physical variables inside the OTG device for determining its effects on the laser beam. The experimental results show the measurements of turbulence parameters C n 2 , l o , and σ I 2 from beam centroids fluctuations, where increases in humidity generated stronger turbulence.

scholarly journals Filtering techniques to enhance optical turbulence forecast performances at short time-scales

2019 ◽  
Vol 492 (1) ◽  
pp. 140-152 ◽  
Author(s):  
E Masciadri ◽  
G Martelloni ◽  
A Turchi
Keyword(s):  
Adaptive Optics ◽  
Time Scales ◽  
Coherence Time ◽  
Atmospheric Conditions ◽  
Atmospheric Parameters ◽  
Optical Turbulence ◽  
Efficient Management ◽  
Science Operations ◽  
Short Time ◽  
Filtering Techniques

ABSTRACT The efficiency of the management of top-class ground-based astronomical facilities supported by adaptive optics (AO) relies on our ability to forecast the optical turbulence (OT) and a set of relevant atmospheric parameters. Indeed, in spite of the fact that the AO is able to achieve, at present, excellent levels of wavefront corrections (a Strehl ratio up to 90 per cent in H band), its performances strongly depend on the atmospheric conditions. Knowing in advance the atmospheric turbulence conditions allows an optimization of the AO use. It has already been proven that it is possible to provide reliable forecasts of the OT (${C_N^2 }$ profiles and integrated astroclimatic parameters such as seeing, isoplanatic angle, wavefront coherence time, etc.) for the next night. In this paper, we prove that it is possible to improve the forecast performances on shorter time-scales (order of 1 or 2 h) with consistent gains (order of 2–8) employing filtering techniques that make use of real-time measurements. This has permitted us to achieve forecasts accuracies never obtained before and reach a fundamental milestone for the astronomical applications. The time-scale of 1 or 2 h is the most critical one for an efficient management of the ground-based telescopes supported by AO. We implemented this method in the operational forecast system of the Large Binocular Telescope (LBT), named Advanced LBT Turbulence and Atmosphere (ALTA) Center that is, at our knowledge, the first operational system providing forecasts of turbulence and atmospheric parameters at short time-scales to support science operations.

scholarly journals Optimizing the accuracy and efficiency of optical turbulence profiling using adaptive optics telemetry for extremely large telescopes

2018 ◽  
Vol 483 (4) ◽  
pp. 4341-4353 ◽  
Author(s):  
Douglas J Laidlaw ◽  
James Osborn ◽  
Timothy J Morris ◽  
Alastair G Basden ◽  
Olivier Beltramo-Martin ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Optical Turbulence ◽  
Large Telescopes

scholarly journals ASTROCLIMATIC STATISTICS AT THE SAYAN SOLAR OBSERVATORY

2020 ◽  
Vol 6 (1) ◽  
pp. 126-133
Author(s):  
Artem Shikhovtsev ◽  
Pavel Kovadlo ◽  
Aleksandr Kiselev
Keyword(s):  
Adaptive Optics ◽  
Solar Observatory ◽  
Line Of Sight ◽  
Solar Telescope ◽  
Vertical Profiles ◽  
Minimum Level ◽  
Optical Turbulence ◽  
Low Intensity ◽  
Spatial Features ◽  
Adaptive Optics System

The paper analyzes meteorological and optical characteristics of the atmosphere at the Sayan Solar Observatory (SSO) and the future 3 m Large Solar Telescope (LST-3). We examine spatial features of changes in astroclimatic characteristics for the Sayan Solar Observatory and Baikal Astrophysical Observatory (BAO). We have obtained a vertical profile of the structural characteristic of air refractive index fluctuations for a low intensity optical turbulence along the line of sight. This profile is an important result because it will allow us to adjust the adaptive optics system of LST-3 to the best astroclimatic conditions when the correction efficiency is maximal. In order to analyze vertical profiles of optical turbulence characteristics and to assess the contribution of individual atmospheric layers to the isoplanatic angle for a minimum level of total turbulence, we give recommendations for the design of multi-conjugated adaptive optics in general and for LST-3 in particular.

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