Bispectral-based optimization algorithms for speckle imaging.

摘要

We present results of a horizontal path imaging experiment using a 0.5-m telescope focused on a target 1.2 km away. We consider an extended representation of a satellite with grey scale and size variations. We imaged at 0.7 (mu)m and found an average atmospheric degradation factor of D/r(sub 0) = 17. We used a slow read-rate, bare CCD detector; thus, we had to deal with additive measurement noise. Our image reconstruction algorithms are based on the complex bispectrum, and we have demonstrated diffraction-limited imaging down to light levels approaching a few photons per speckle per resolution area. We have paid careful attention to the effects of additive noise on the reconstruction process and have shown that they can be adequately overcome. We present some new algorithms based on conjugate gradients and least squares. We demonstrate that these algorithms can improve image quality. 18 refs., 4 figs.