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Progress of the Large Interferometer at CERGA

Published online by Cambridge University Press:  12 April 2016

A. Labeyrie ,
G. Schumacher ,
C. Thom ,
M. Dugué ,
F. Foy ,
R. Foy ,
P. Cormier  and
F. Vakili
A. Labeyrie
Affiliation:
C E R G A, Caussols, 06460 Saint-Vallier de Thiey, France
G. Schumacher
Affiliation:
C E R G A, Caussols, 06460 Saint-Vallier de Thiey, France
C. Thom
Affiliation:
C E R G A, Caussols, 06460 Saint-Vallier de Thiey, France
M. Dugué
Affiliation:
C E R G A, Caussols, 06460 Saint-Vallier de Thiey, France
F. Foy
Affiliation:
C E R G A, Caussols, 06460 Saint-Vallier de Thiey, France
R. Foy
Affiliation:
C E R G A, Caussols, 06460 Saint-Vallier de Thiey, France
P. Cormier
Affiliation:
C E R G A, Caussols, 06460 Saint-Vallier de Thiey, France
F. Vakili
Affiliation:
C E R G A, Caussols, 06460 Saint-Vallier de Thiey, France

Summary

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The coude beams from a pair of 1.5 meter telescopes are recombined to achieve coherent aperture synthesis. The spherical telescopes move along a 70-meter baseline, expandable to 300 meters. For the VLT, a grid of railway tracks with 2-D carriages meets the requirements for incoherent and coherent observing.

Steps in the design and construction of a coherent telescope array have been described previously (Labeyrie, 1982, 1984). In 1975, it was first verified that stellar light from two telescopes could be recombined coherently. In 1978, it was decided to develop spherical mounts for 1.5-meter telescopes. Among the expected features were: 1. coude focus with only one flat mirror; 2. wheels for mobility along railway tracks; 3. structural stiffness for interferometric stability, also implying vibration amplitudes inferior to 0.1 micrometer at each reflective surface. This last and most critical requirement implies materials which have to be stiff and also damped.

Type
III. Atmospheric Seeing, Interferometry, Speckle, MMTs and Arrays
Information
International Astronomical Union Colloquium , Volume 79: Very Large Telescopes, their Instrumentation and Programs , 1984 , pp. 267 - 278
Copyright
Copyright © ESO 1984

References

“Coherent arrays of separate optical telescopes in space; project TRIO” Labeyrie, A., Kibblewhite, J., de Graauw, T., Noordam, J., Weigelt, G., and Roussel, H., in “Very long baseline interierometry techniques”, Toulouse, August-September 1982, CNES.Google Scholar
“Construction of coherent arrays” Dugué, M., Labeyrie, A., and Schumacher, G., ESO’s Very Large Telescope, Cargèse, May 1983.Google Scholar
“Very large optical arrays using boule type telescopes” Grundmann, G.J., Odgers, W.A..Google Scholar
“The versatil arrays” Angel, .Google Scholar
“Stellar speckle interferometry” Dainty, J.C., Topics in Applied Physics, p. 255, vol. 9, Laser speckle and related phenomena, ed. Dainty, J.C..Google Scholar