The diffraction-limited spatial cut-off frequency D/(lambda) of a telescope aperture is not an absolute limit to imaging resolution, and various methods exist to obtain spatial information at frequencies much higher than D/(lambda) under specialized circumstances. In particular, spectrally dissimilar objects can be discerned at separations far smaller than the Airy radius, by exploiting both the spatial and spectral information available. This general method is applied in differential speckle interferometry and chromatic position difference imaging. We describe proposed experiments, using the University of Durham's ELECTRA adaptive optics instrument, to perform a variant of chromatic position different imaging at IR wavelengths, but incorporating the very large resolution gain provided by AO image correction. This method, related in principle to differential speckle interferometry, involves measuring the shift of image centroid with wavelength across a spectrally dispersed image. The implementation of this experiment on ELECTRA requires only a simple modification to the standard ELECTRA optical configuration. The optical arrangement is described, and examples of astronomical applications are presented.

Date Published: 27 September 1999
PDF: 8 pages
Proc. SPIE 3762, Adaptive Optics Systems and Technology, (27 September 1999); doi: 10.1117/12.363593

Published in SPIE Proceedings Vol. 3762:
Adaptive Optics Systems and Technology
Robert K. Tyson; Robert Q. Fugate, Editor(s)