Optical interferometry: Encyclopedia II - Optical interferometry - Astronomical optical interferometry

Optical interferometry - Astronomical optical interferometry

Later, optical interferometry was used on the Mount Wilson Observatory's reflector telescope in order to measure the diameters of stars. This method was extended to measurements using separated telescopes by Johnson, Betz and Towns (1974) in the infrared and by Labeyrie (1975) in the visible. The red giant star Betelgeuse was among the first to have its diameter determined in this way. In the 1980s the aperture synthesis technique was extended to visible light and infrared astronomy by the Cavendish Astrophysics Group, providing the first very high resolution images of nearby stars. In 1995 this technique was demonstrated on an array of separate optical telescopes for the first time, allowing a further improvement in resolution, and allowing even higher resolution imaging of stellar surfaces. The same techniques have now been applied at a number of other astronomical telescope arrays, including the Navy Prototype Optical Interferometer, the VLTI, the CHARA array, the IOTA array and the MRO Interferometer. A detailed description of the development of astronomical optical interferometry can be found here. Impressive results were obtained in the 1990s, with the Mark III measuring diameters of 100 stars and many accurate stellar positions, COAST and NPOI producing many very high resolution images, and ISI measuring stars in the mid-infrared for the first time. Some scientists exaggerated the benefits of combining large diameter (adaptive optics corrected) telescopes for near-infrared interferometry, and this left many astronomers disappointed with new arrays utilizing small numbers of large telescopes which came online in the early 2000s. For details of individual instruments, see the list of astronomical interferometers at visible and infrared wavelengths.

Optical interferometry - For further information see

• John E. Baldwin and Chris A. Haniff. The application of interferometry to optical astronomical imaging. Phil. Trans. A, 360, 969-986, 2001. (download PostScript file)
• J. E. Baldwin. Ground-based interferometry - the past decade and the one to come. In Interferometry for Optical Astronomy II, volume 4838 of Proc. SPIE, page 1. 22-28 August 2002, Kona, Hawaii, SPIE Press, 2003. (download PostScript file)
• J. D. Monnier, Optical interferometry in astronomy, Reports on Progress in Physics, 66, 789-857, 2003 IoP. (download PDF file)

See also: History of astronomical interferometry

Adapted from the Wikipedia article "Astronomical optical interferometry", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki