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Heterodyne Interferometry in the Infrared

Published online by Cambridge University Press:  19 July 2016

C.H. Townes ,
M. Bester ,
W.C. Danchi ,
C.G. Degiacomi  and
L.J. Greenhill
C.H. Townes
Affiliation:
Space Sciences Laboratory and Physics Department, University of California at Berkeley, Berkeley, CA 94720 USA
M. Bester
Affiliation:
Space Sciences Laboratory and Physics Department, University of California at Berkeley, Berkeley, CA 94720 USA
W.C. Danchi
Affiliation:
Space Sciences Laboratory and Physics Department, University of California at Berkeley, Berkeley, CA 94720 USA
C.G. Degiacomi
Affiliation:
Space Sciences Laboratory and Physics Department, University of California at Berkeley, Berkeley, CA 94720 USA
L.J. Greenhill
Affiliation:
Space Sciences Laboratory and Physics Department, University of California at Berkeley, Berkeley, CA 94720 USA

Abstract

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The University of California Infrared Spatial Interferometer (ISI) for the 10 μm wavelength region is briefly described along with results obtained on prominent stars and on atmospheric phenomena. The system has two movable telescopes of 1.65 m aperture. It operates in principle like a modern radio interferometer, using heterodyne detection, CO2 laser local oscillators, RF delay lines, and lobe rotation to maintain a fixed-frequency fringe rate.

Rather extensive measurements have been made on atmospheric pathlength or phase fluctuation characteristics which show substantial deviations from the Kolmogorov-Taylor model, fortunately in a direction favoring adaptive optics, long baselines, and the use of infrared wavelengths. Outer scales as small as about 10 meters occur under good seeing conditions. Visibility results on 13 stars show that 6 of them have dust shells rather far from the star and give evidence for episodic emission of gas. Others of the 13 stars also vary with time, but are characterized by more continuous emission and dust formation near the stars at temperatures as high as 1300 K.

Type
Transfer of Techniques
Information
Symposium - International Astronomical Union , Volume 158: Very High Angular Resolution Imaging , 1994 , pp. 19 - 25
Copyright
Copyright © Kluwer 1994 

References

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