5 July 2000 Least-squares estimation and group delay in astrometric interferometers
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Abstract
The Palomar Testbed Interferometer is a long-baseline interferometer that uses both phase and group-delay measurements for narrow-angle astrometry. The group-delay measurements are performed using 5 spectral channels across the band from 2.0 to 2.4 micrometers . Group delay is estimated from phasors (sine and cosine of fringe phase) calculated for each spectral channel using pathlength modulation of one wavelength. Normally the group delay is estimated to be the delay corresponding to the peak of the power spectrum of these complex phasors. The Fourier transform does not however yield a least-squares estimate of the delay. Nevertheless, the precision of phase estimation can be achieved in a group-delay estimate using a least-squares approach. We describe the least-squares group-delay estimator that has been implemented at PTI and illustrate its performance as applied to narrow-angle astrometry.
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Peter R. Lawson, Peter R. Lawson, M. Mark Colavita, M. Mark Colavita, Philip J. Dumont, Philip J. Dumont, Benjamin F. Lane, Benjamin F. Lane, } "Least-squares estimation and group delay in astrometric interferometers", Proc. SPIE 4006, Interferometry in Optical Astronomy, (5 July 2000); doi: 10.1117/12.390232; https://doi.org/10.1117/12.390232
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