First on-sky results of the CO-SLIDAR C^2_n profiler

Voyez, Juliette; Robert, Clélia; Conan, Jean-Marc; Mugnier, Laurent M.; Samain, E.; Ziad, Aziz

doi:10.1364/oe.22.010948

Cited by 20 publications

(6 citation statements)

References 21 publications

(20 reference statements)

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“…AOSH images simultaneously provide various data: slopes, intensities, and spot sizes. When short exposures are used, the information provided by both slopes and intensities (i.e., scintillation) can be used to retrieve Cn 2 profile using correlations of these data from two separated stars (Robert et al 2011;Voyez et al 2013). When long exposures are used, it is feasible to retrieve the atmospheric seeing in the line of sight from the spot sizes in the sub-apertures, with the advantage of being insensitive to the telescope field stabilization (Martinez et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Multiwavelength active-optics Shack-Hartmann sensor for monitoring seeing and turbulence outer scale

Martínez

2014

A&A

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Context. Real-time seeing and outer-scale estimation at the location of the focus of a telescope is fundamental for predicting the adaptive-optics system's dimensioning and performance, as well as for the operational aspects of instruments. Aims. This study attempts to take advantage of multiwavelength long-exposure images to instantaneously and simultaneously derive the turbulence outer scale and seeing from the full width at half maximum (FWHM) of seeing-limited images taken at the focus of a telescope. These atmospheric parameters are commonly measured in most observatories by different methods located away from the telescope platform, thus differing from the effective estimates at the focus of a telescope, mainly because of differences in pointing orientation, height above the ground, or local seeing bias (dome contribution). Methods. Long-exposure images can either be provided directly by any multiwavelength scientific imager or spectrograph or, alternatively from a modified active-optics Shack-Hartmann sensor (AOSH). From measuring the AOSH sensor spot point spread function FWHMs simultaneously at different wavelengths, one can estimate the instantaneous outer scale in addition to seeing. Results. Multiwavelength long-exposure images provide access to accurate estimates of r 0 and L 0 by adequate means as long as precise FWHMs can be obtained. Although AOSH sensors are specified to measure not spot sizes but slopes, real-time r 0 , and L 0 measurements from spot FWHMs can be obtained at the critical location where they are needed with major advantages over scientific instrument images: insensitivity to the telescope field stabilization, and continuous availability. Conclusions. Assuming an alternative optical design that allows simultaneous multiwavelength images, the AOSH sensor benefits from all the advantages of real-time seeing and outer scale monitoring. With the substantial interest in the design of extremely large telescopes, such a system could be of considerable importance.

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Section: Introductionmentioning

confidence: 99%

Multiwavelength active-optics Shack-Hartmann sensor for monitoring seeing and turbulence outer scale

Martínez

2014

A&A

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“…When temperature stratification is unstable under the convective boundary layer (CBL), especially within the well-mixed part ( 0.2 ∼ 0.8 z/z i , where z i is the height of CBL), the source of turbulence becomes mainly buoyancy-driven. Then, due to the nonlocal large-eddy heat flux, Equations ( 4)-( 6) and (10) that are based on K-theory failed to deal with the "zero/counter-gradient" region, where ∂Θ/∂z ≥ 0 while w θ > 0 [68,74]. Likewise, temperature structure constant C 2 T and refractive index structure constant C 2 n are not proportional to (dT/dz) 2 and M 2 anymore.…”

Section: Convective Boundary Layermentioning

confidence: 99%

“…At present, there are some common methods for C 2 n detection. For instance, in areas of astronomy and satellite-ground laser communication, C 2 n profiles can be obtained by Slope Detection and Ranging (SLODAR) [9], Coupled Slope and Scintillation Detection and Ranging (CO-SLIDAR) [10], etc. [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Turbulence Detection in the Atmospheric Boundary Layer Using Coherent Doppler Wind Lidar and Microwave Radiometer

Jiang

Yuan

et al. 2022

Remote Sensing

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The refractive index structure constant (Cn2) is a key parameter used in describing the influence of turbulence on laser transmissions in the atmosphere. Three different methods for estimating Cn2 were analyzed in detail. A new method that uses a combination of these methods for continuous Cn2 profiling with both high temporal and spatial resolution is proposed and demonstrated. Under the assumption of the Kolmogorov “2/3 law”, the Cn2 profile can be calculated by using the wind field and turbulent kinetic energy dissipation rate (TKEDR) measured by coherent Doppler wind lidar (CDWL) and other meteorological parameters derived from a microwave radiometer (MWR). In a horizontal experiment, a comparison between the results from our new method and measurements made by a large aperture scintillometer (LAS) is conducted. The correlation coefficient, mean error, and standard deviation between them in a six-day observation are 0.8073, 8.18 × 10−16 m−2/3, and 1.27 × 10−15 m−2/3, respectively. In the vertical direction, the continuous profiling results of Cn2 and other turbulence parameters with high resolution in the atmospheric boundary layer (ABL) are retrieved. In addition, the limitation and uncertainty of this method under different circumstances were analyzed, which shows that the relative error of Cn2 estimation normally does not exceed 30% under the convective boundary layer (CBL).

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“…At present, there are some common methods for 𝐶 𝑛 2 detection. For instance, there are methods derived from astronomy and satellite-ground laser communication areas, such as the Slope Detection and Ranging (SLODAR) (Butterley et al, 2006), Coupled Slope and Scintillation Detection and Ranging (CO-SLIDAR) (Voyez et al, 2014), etc. (Fusco and Costille, 2010;Otoniel Canuet, 2015;Voyez et al, 2012).…”

mentioning

confidence: 99%

Turbulence Detection in the Atmospheric Boundary Layer using Coherent Doppler Wind Lidar and Microwave Radiometer

Jiang

Yuan

et al. 2021

Preprint

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Abstract. The refractive index structure constant (Cn2) is a key parameter in describing the influence of turbulence on laser transmission in the atmosphere. A new method for continuous Cn2 profiling with both high temporal and spatial resolution is proposed and demonstrated. Under the assumption of the Kolmogorov “2/3 law”, the Cn2 profile can be calculated by using the wind field and turbulent kinetic energy dissipation rate (TKEDR) measured by coherent Doppler wind lidar (CDWL) and other meteorological parameters derived from microwave radiometer (MWR). In the horizontal experiment, a comparison between the results from our new method and measurements made by a large aperture scintillometer (LAS) is conducted. Except for the period of stratification stabilizing, the correlation coefficient between them in the six-day observation is 0.8389, the mean error and standard deviation is 1.09 × 10−15 m−2/3 and 2.14 × 10−15 m−2/3, respectively. In the vertical direction, the continuous observation results of Cn2 and other turbulence parameter profiles in the atmospheric boundary layer (ABL) are retrieved. More details of the atmospheric turbulence can be found in the ABL owe to the high temporal and spatial resolution of MWR and CDWL (spatial resolution of 26 m, temporal resolution of 147 s).

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First on-sky results of the CO-SLIDAR C^2_n profiler

Cited by 20 publications

References 21 publications

Multiwavelength active-optics Shack-Hartmann sensor for monitoring seeing and turbulence outer scale

Multiwavelength active-optics Shack-Hartmann sensor for monitoring seeing and turbulence outer scale

Turbulence Detection in the Atmospheric Boundary Layer Using Coherent Doppler Wind Lidar and Microwave Radiometer

Turbulence Detection in the Atmospheric Boundary Layer using Coherent Doppler Wind Lidar and Microwave Radiometer

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