Abstract. The measurement of the strength and velocity of atmospheric optical turbulence using a generalised SCIDAR technique is outlined and demonstrated. This method allows the full turbulent profile to be characterised from the telescope pupil up to any desired altitude. A number of example profiles from various astronomical observing sites are presented.

The measurement of the strength of atmospheric optical turbulence by use of a modified generalized SCIDAR (scintillation detection and ranging) inversion technique is outlined and demonstrated. This new method for normalizing and inverting scintillation covariances incorporates the geometry specific to generalized SCIDAR. Examples of profiles from two astronomical observation sites are presented.

No abstract

A B S T R A C TWe present the results of a mesospheric sodium monitoring programme at La Palma carried out through five campaigns of one week each, from 1999 September to 2000 August. The yearly averaged parameters of the layer (the sodium column density and the width) are given. We show that the short time-scale dynamics of the layer are governed by the sporadic layers with an average frequency of one event per night. The influence of the short time-scale dynamics of the layer on an adaptive optics system working on the William Herschel Telescope is quantified. It appears that it is a small effect in terms of defocus error. Finally, we present data obtained during the Perseid meteor shower and show that the dynamics of the sodium layer undergoes a transition with the meteoric activity.

We present the results of contemporaneous seeing measurements using a multi‐object Shack–Hartmann wavefront sensor, SCIDAR optical turbulence profiling, and a DIMM seeing monitor at the William Herschel Telescope in La Palma. The data are used to determine the accuracy with which angular anisoplanatism can be predicted from generalized SCIDAR turbulence profile measurements. Theoretical predictions of the angular correlation of the Zernike aberration coefficients, based on the SCIDAR profiles, agree with direct measurements from the wavefront sensor to within 7 per cent rms. Estimates of the total seeing (integrated optical turbulence strength) from the methods agree to 10 per cent rms. We conclude that SCIDAR represents a reliable means for calibration of the spatially and temporally variable point‐spread function for imaging with adaptive optics in astronomy.

No abstract

We report what are to our knowledge the first experimental results of coherence enhancement that use polarization to separate coherent and incoherent paths.

No abstract