Image Processing Reference
7.5 Stabilized Long-Baseline Interferometers
Long-baseline interferometers require stabilization of their beams because of atmo-
spheric fluctuations prior to the astronomical light reaching the telescope and from
fluctuations that occur between the telescope and the beam combiner. As such,
nearly all large optical interferometers have sophisticated beam stabilization sys-
tems as an integral part of their optical train.
Cambridge Optical Aperture Synthesis Telescope
The Cambridge Optical Aperture Synthesis Telescope (COAST) is a multielement,
long-baseline interferometer developed at Cambridge University in the United
Kingdom. Active optics are used in conjunction with small-aperture telescopes to
provide beam stabilization. The maximum baseline of the interferometer is 100 m.
This allows the interferometer to observe bright objects with angular resolution of
Haniff, C.A., J.E. Baldwin, A.G. Basden, N.A. Bharmal, R.C. Boysen, D.F.
Buscher, A.V. George, J. Keen, C.D. Mackay, B. O'Donovan, D. Pearson, J.
Rogers, B. Seneta, H. Thorsteinsson, N.D. Thureau, R.N. Tubbs, P.J. Warner,
D.M.A. Wilson, J.S. Young, “Progress at COAST 2000-2002,” Proceedings
of SPIE , 4838 , 19-27 (2003).
Center for High Angular Resolution Astronomy
The Center for High Angular Resolution Astronomy (CHARA) is operated by
Georgia State University at the Mount Wilson Observatory near Pasadena, Califor-
nia. The facility is based on six 1-m aperture telescopes with a maximum baseline
of 330 m. A tip-tilt system near the beam combiner compensates for instrument ef-
ten Brummelaar, T. A., et al., “First results from the CHARA Array. II. A De-
scription of the instrument,” Astrophysical Journal , 628 , 453-465 (2005).
European Southern Observatory
The four 8.2-m telescopes of the VLT can be combined into an interferometer. In
addition, three 1.8-m auxiliary telescopes (AT) are equipped only with tip-tilt,
since most of the interferometry work at this facility is carried out in the infrared re-