相关论文: Mesosphere Sodium Column Density and the Sodium La…
The performance of adaptive optics systems employing sodium laser guide stars can be improved by continuously monitoring the vertical density structure of mesospheric sodium along the line of sight. We demonstrate that sodium density…
The brightness and height of the sodium laser guide star of adaptive optics could vary significantly due to the temporal dynamics of sodium column density and the mean height of sodium layer. To measure these dynamics, an independent sodium…
We have developed and tested a novel method, based on LIDAR, of measuring the height and profile of the mesospheric sodium layer using a continuous wave laser. It is more efficient than classical LIDAR as the laser is on for 50% of the…
Detailed knowledge of the mesopheric sodium layer characteristics is crucial to estimate and optimize the performance of Laser Guide Star (LGS) assisted Adaptive Optics (AO) systems. In this paper, we present an analysis of two sets of data…
Large telescope's adaptive optics (AO) system requires one or several bright artificial laser guide stars to improve its sky coverage. The recent advent of high power sodium laser is perfect for such application. However, besides the output…
Over the last few years increasing consideration has been given to the study of Laser Guide Stars (LGS) for the measurement of the disturbance introduced by the atmosphere in optical and near-infrared astronomical observations from the…
Context: Sodium laser guide stars (LGS) are about to enter a new range of laser powers. Previous theoretical and numerical methods are inadequate for accurate computations of the return flux and hence for the design of the next-generation…
Sodium Laser Guide Stars (LGSs) are elongated sources due to the thickness and the finite distance of the sodium layer. The fluctuations of the sodium layer altitude and atom density profile induce errors on centroid measurements of…
We demonstrate backward-directed continuous-wave (cw) emission at 2.21 {\mu}m generated on the 4P3/2-4S1/2 population-inverted transition in Na vapors two-photon excited with resonant laser light at 589 and 569 nm. Our study of power and…
Optical interferometry has been successful at achieving milliarcsecond resolution on bright stars. Imaging performance can improve greatly by increasing the number of baselines, which has motivated proposals to build large (~ 100 m) optical…
Spectral hole burning reduces sodium laser guide star efficiency. Due to photon recoil, atoms that are initially resonant with the single-frequency laser get Doppler shifted out of resonance, which reduces the return flux. Frequency-chirped…
A continuous guided atomic beam of $^{88}\mathrm{Sr}$ with a phase-space density exceeding $10^{-4}$ in the moving frame and a flux of $3 \times 10^{7} \, \mathrm{at \, s^{-1}}$ is demonstrated. This phase-space density is around three…
The Giant Magellan Telescope will use laser tomography adaptive optics to correct for atmospheric turbulence using artificial guide stars created in the sodium layer of the atmosphere (altitude ~95km). The sodium layer has appreciable…
The Mesosphere is interested by important chemical and dynamical phenomena, so observation of its Sodium layer's behavior has became a common target of several research plans all over the world. In order to study its dynamical and chemical…
Magnetic field sensing provides crucial insights into various geophysical phenomena such as atmospheric currents, crustal magnetism, and oceanic circulation. In this paper, a method for remote detection of magnetic fields using mesospheric…
We report experimental results on the first on-sky observation of atomic spin precession of mesospheric sodium driven by polarization modulation of a continuous-wave laser. The magnetic resonance was remotely detected from the ground by…
We present first measurements of the degree of linear polarization of distant comets C/2010 S1 (LINEAR) and C/2010 R1 (LINEAR) at heliocentric distances r= 5.9 - 7.0 AU. Observations were carried out with the SCORPIO-2 focal reducer at the…
We have constructed an analytical model to simulate the behavior of an adaptive optics system coupled with a sodium laser guide star. The code is applied to a 3.6-m and 8m class telescopes. The results are given in terms of Strehl ratio and…
We compute the cosmic star formation rate (SFR) and the rest-frame comoving luminosity density in various pass-bands as a function of redshift using large-scale \Lambda-CDM hydrodynamical simulations with the aim of understanding their…
The mechanisms responsible for ultraviolet to mid-infrared light generation in sodium vapours two-photon excited with continuous-wave sub-100 mW power resonant laser radiation are elucidated from orbital angular momentum transfer of the…