Parameter exploration for spectral estimation of speckle imagery

Efforts to extend speckle-based focal plane array (FPA) modulation transfer function (MTF) measurements beyond the detector Nyquist frequency have unearthed challenging spectral estimation issues. In an attempt to better understand the task of speckle image spectral estimation, this paper explores the nuances of various estimation techniques, making comparisons using both real speckle imagery and simulated data. Parameters and features of the techniques investigated include number of image realizations, the size of image realizations and applications of windows to speckle imagery spectral estimation. Real-world testing considerations such as laser stability and the challenge of collecting significant numbers of independent image realizations are addressed in the analysis. Results show the advantage increasing the number of realizations has on estimation variance, the robustness of smaller realization segments when battling speckle field imagery spatial non-uniformities and the benefits of windowing image segments with regards to power spectral density (PSD) estimation accuracy.