Spatiotemporal structure of a laser beam over 144 km in a Canary Islands experiment

Abstract

We analyzed the observations of scintillations in a laser beam (532 nm, ~200 mW power) traveling along a 144 km path at an altitude of 2.2-2.4 km above sea level, just above the atmospheric boundary layer, between the islands of La Palma and Tenerife. The observations were performed during nighttime on 18 July 2011, by means of a telescope with an aperture diameter of 1 m. Strong scintillations were observed. The estimates of spatial spectra and correlation functions indicated that the observed intensity fields possess, statistically, a locally isotropic structure, which agrees with the idea of a locally isotropic turbulence. The estimates of spatial autospectra and autocorrelation functions of the intensity field indicated that the characteristic scale of the internal structure of the observed clusters is 6.5-8 mm, while the characteristic size of the clusters is 4-5 cm. The major contribution to the observed scintillations comes from the inhomogeneities of the intensity field with scales from 1-2 cm up to 10-12 cm. The analysis of the cross-spectra indicated that the hypothesis of frozen turbulence introduced by Taylor can be used for the description of spatiotemporal structure of intensity fluctuations of laser beams traveling through long paths in the atmosphere.

Profiling wind and greenhouse gases by infrared-laser occultation: results from end-to-end simulations in windy air

“…The IR signals operate best under clear air conditions, which means no influence of clouds but of other atmospheric broadband effects like defocusing loss (Kursinski et al, 2000), Rayleigh scattering and aerosol extinction (Salby, 2012;Liou, 2002), and scintillations (Andrews and Philips, 2005;Gurvich et al, 2012). Schweitzer et al (2011a) have analyzed these clear air influences in detail and Proschek et al (2011) have studied the GHG retrieval performance under these conditions.…”

Optical phase under deep turbulence conditions

“…The following short review of experimental papers [3], [4], [5], and [6] is included in response to the request of the Topical Editor.…”

“…Recently, in [6], strong scintillation of the 532 nm laser beam was reported on the same propagation path on the Canary Islands as in [4]. Similar to [5], this experiment was designed to study the spatial-temporal statistics of scintillation but was limited to the 532 nm laser wavelength.…”

“…Similar to [5], this experiment was designed to study the spatial-temporal statistics of scintillation but was limited to the 532 nm laser wavelength. The authors of [6], in contrast to [5], performed a thorough statistical investigation of the irradiance images at the entrance pupil of 1 m telescope, and concluded that, as predicted by conventional propagation theory, irradiance has statistically homogeneous and isotropic statistics. Somewhat surprisingly, even for varying conditions along a long propagation path, they found that the Taylor hypothesis is still valid, albeit for a limited range of spatial frequencies.…”

A numerical simulation method for laser radiation propagating through large-scale atmospheric inhomogeneities

“…Many long-path experiments [13][14][15][16][17][18][19][20] point to significant deviations of the results from this model.…”