Improvement of rang one phase estimation (ROPE) autofocusing technique

摘要

This paper presents an improved rank one phase error estimate (ROPE) autofocus technique. Compared with ROPE, the improved algorithm (IROPE) has two distinct advantages. First, its model is more actual, so its property of robustness is better. Second, at the beginning of it's iteration process, the initialized valves are set up approximately. The approximation is more exact as compared to the blind initialization of ROPE. IROPE estimator of phase error is maximum-likelihood (ML) one, and, under some special conditions, its estimator is the same as that of phase gradient autofocus (PGA), which is linear unbiased minimum variation (LUMV) one. Both ROPE and PGA are subsets of IROPE.