Wavefront outer scale deduced from interferometric dispersed fringes

In addition to site characterization, measurements of critical atmospheric parameters are required to design and to optimize future adaptive optic systems and long-baseline interferometers. It is possible to estimate seeing conditions by processing data obtained with existing High Angular Resolution instruments. We report the results of joint observations with the GI2T interferometer and the GSM site-testing monitor performed over a period of several nights. We compared estimates of the wavefront outer scale done at various baselines as well as the seeing (Fried’s parameter). We processed interferometric data by calculating power spectra of dispersed fringe images. Deduced measurements of the optical path difference lead to the estimates of the outer scale. We found that the outer scale values obtained from the GI2T data are mostly in the 5−30 m range, in good agreement with GSM measurements.

[1]  M. Shao,et al.  Atmospheric phase measurements with the Mark III stellar interferometer. , 1987, Applied optics.

[2]  F. Roddier,et al.  Interferometric imaging in optical astronomy , 1988 .

[3]  C. Aime,et al.  Polychromatic transfer functions in stellar speckle interferometry , 1989 .

[4]  Julien Borgnino,et al.  Comparison of measurements of the outer scale of turbulence by three different techniques. , 2004, Applied optics.

[5]  F Roddier,et al.  Long-baseline Michelson interferometry with large ground-based telescopes operating at optical wavelengths. I. General formalism. Interferometry at visible wavelengths , 1984 .

[6]  Keh-Shew Lu,et al.  DIGITAL FILTER DESIGN , 1973 .

[7]  R Conan,et al.  From the grating scale monitor to the generalized seeing monitor. , 2000, Applied optics.

[8]  A. Blazit,et al.  Dispersed fringe tracking with the multi-r(0) apertures of the Grand Interféromètre à 2 Télescopes. , 1996, Applied optics.

[9]  Christopher A. Haniff,et al.  Atmospheric phase fluctuation measurement: interferometric results from the WHT and COAST telescopes , 1994, Astronomical Telescopes and Instrumentation.

[10]  Julien Borgnino,et al.  EFFECTS OF ATMOSPHERIC SPECTRAL DECORRELATION ON VISIBILITY MEASUREMENTS IN MICHELSON INTERFEROMETRY , 1997 .

[11]  D. Buscher,et al.  Interferometric seeing measurements at the La Palma Observatory , 1991 .

[12]  Denis Mourard,et al.  Removing the photon-centroiding hole in optical stellar interferometry , 1998 .

[13]  David Le Mignant,et al.  Atmospheric turbulence characterization with the Keck adaptive optics systems. I. Open-loop data. , 2003, Applied optics.

[14]  A. Agabi,et al.  Optical parameters relevant for High Angular Resolution at Paranal from GSM instrument and surface layer contribution , 2000 .

[15]  Influence of exposure time on spectral properties of turbulence-degraded astronomical images , 1975 .

[16]  William C. Danchi,et al.  Atmospheric Fluctuations: Empirical Structure Functions and Projected Performance of Future Instruments , 1992 .

[17]  M. M. Colavita,et al.  Atmospheric Turbulence Measurements with the Palomar Testbed Interferometer , 2001, astro-ph/0102052.

[18]  C. Aime.  Teaching astronomical speckle techniques , 2001 .

[19]  Julien Borgnino,et al.  Theoretical spatiotemporal analysis of angle of arrival induced by atmospheric turbulence as observed with the grating scale monitor experiment , 1997 .

[20]  Julien Borgnino,et al.  Effect of a finite spatial-coherence outer scale on the covariances of angle-of-arrival fluctuations , 1992 .

[21]  John Davis,et al.  Atmospheric path variations for baselines up to 80m measured with the Sydney University Stellar Interferometer , 1995 .

[22]  M. M. Colavita,et al.  Interferometric seeing measurements on Mt. Wilson: power spectra and outer scales. , 1995, Applied optics.

[23]  Measurements of Stellar Speckle Interferometry Lens-atmosphere Modulation Transfer Function , 1979 .

[24]  J. Mariotti,et al.  Pathlength stability of synthetic aperture telescopes - The case of the 25 CM CERGA interferometer , 1984 .

[25]  Thierry Fusco,et al.  NAOS on-line characterization of turbulence parameters and adaptive optics performance , 2004 .

[26]  T. W. Parks,et al.  Digital Filter Design , 1987 .

[27]  B. Roy Frieden,et al.  Probability, Statistical Optics, And Data Testing , 1982 .

[28]  Aziz Ziad,et al.  Measurements of the wavefront outer scale at Paranal: influence of this parameter in interferometry , 2000, Astronomical Telescopes and Instrumentation.