LAKHAL , Lyes

The one dimensional point spread function for long exposure frames of the whole system atmosphere-instrument is deduced from solar limb observations using data recorded at Calern Observatory (France). It is then compared to the theoretical one deduced from the Von Karman model. Good agreement is found allowing to deduce the spatial coherence...

The one-dimensional point spread function for long-exposure frames of the whole system atmosphere - instrument is calculated from solar limb observations using data recorded at OCA Observatory (France). It is then compared to the theoretical one deduced from the Von Karman model and various wave-front structure functions. Good agreement is...

Diameter measurements performed with the solar astrolabe are affected by instrumental and atmospheric effects. The problem is to know how these effects contribute to the error on diameter measurements. Thus, a numerical simulation is developed to bring some responses to this problem. For this purpose, synthetic images of the Sun similar to the...

Good edge extraction from temporal series of solar images is fundamental in the solar astrolabe experiment. Noise and spots in images cause however, difficulties to extract an accurate solar edge. We present in this paper a new image-processing method which solves this problem and thus improves the characteristics of the solar astrolabe...

The statistical analysis of angle-of-arrival fluctuations appears to be well adapted to monitor the optical effects induced by the atmospheric turbulence on the images observed using ground-based telescopes. In daytime, these fluctuations may be easily observed on solar limb images. In the context of the comparison planned between solar...

Object images obtained by mean of ground based instrument are degraded by the earth atmosphere. Indeed, the wave-front at the entrance of the instrument pupil, present phase and amplitude random fluctuations depending of the time, the position and the line of sight. The recorded images are consequently filtered leading to bad measurements of...