Framework for improving DoLP and AoLP reconstruction quality in microgrid polarimeters.

In polarimetric imaging, degree and angle of linear polarization (DoLP and AoLP, respectively) are computed from ratios of Stokes parameters. In snapshot imagers, DoLP and AoLP are degraded by inherent mismatches between the spatial bandwidth of the S, S, and S parameters reconstructed by demosaicking from microgrid polarizer array (MPA)-sampled data. To overcome this, we rigorously show that log-MPA-sampled data approximately decouples DoLP and AoLP from the intensity component (S) in the spatial Fourier domain.

United States Air Force Research Laboratory: introduction to the focus issue.

This focus issue on the United States Air Force Research Laboratory (AFRL) spans the latest trends in imaging and detectors, atmospheric characterization, laser sources and propagation, optics and optical assemblies, optical characterization of materials, photonics, optical processing, and machine learning for applications that cover everything from stellar interferometry to studying damage to the plasma membranes of living cells.

Joint object classification and turbulence strength estimation using convolutional neural networks.

In a recent paper, Kee et al. [Appl. Opt.

Airborne validation of the general image quality equation 5.

The general image quality equation (GIQE) maps imaging system parameters to performance in terms of common detection and recognition tasks. Changes to the National Imagery Interpretation Rating Scale led to the development of GIQE version 5 in 2015. The purpose of this paper is to provide a review of GIQE 5 applications in the literature, a tutorial on its use, and, for the first time , an independent validation of the new model along with comparisons to GIQEs 3 and 4.

Spatial stabilization of deep-turbulence-induced anisoplanatic blur.

We explore the feasibility of post-detection restoration when imaging through deep turbulence characterized by extreme anisoplanatism. A wave-optics code was used to simulate relevant short-exposure point spread functions (PSFs) and their decorrelation as a function of point-source separation was computed. In addition, short-exposure images of minimally extended objects were simulated and shown to retain a central lobe that is clearly narrower than the long-exposure counterpart.

Improved microgrid arrangement for integrated imaging polarimeters.

For almost 20 years, microgrid polarimetric imaging systems have been built using a 2×2 repeating pattern of polarization analyzers. In this Letter, we show that superior spatial resolution is achieved over this 2×2 case when the analyzers are arranged in a 2×4 repeating pattern. This unconventional result, in which a more distributed sampling pattern results in finer spatial resolution, is also achieved without affecting the conditioning of the polarimetric data-reduction matrix.

Stokes image reconstruction for two-color microgrid polarization imaging systems.

The Air Force Research Laboratory has developed a new microgrid polarization imaging system capable of simultaneously reconstructing linear Stokes parameter images in two colors on a single focal plane array. In this paper, an effective method for extracting Stokes images is presented for this type of camera system. It is also shown that correlations between the color bands can be exploited to significantly increase overall spatial resolution.

Super-resolution for imagery from integrated microgrid polarimeters.

Imagery from microgrid polarimeters is obtained by using a mosaic of pixel-wise micropolarizers on a focal plane array (FPA). Each distinct polarization image is obtained by subsampling the full FPA image. Thus, the effective pixel pitch for each polarization channel is increased and the sampling frequency is decreased.

Multichannel blind deconvolution of polarimetric imagery.

A maximum likelihood blind deconvolution algorithm is derived for incoherent polarimetric imagery using expectation maximization. In this approach, the unpolarized and fully polarized components of the scene are estimated along with the corresponding angles of polarization and channel point spread functions. The scene state of linear polarization is determined unambiguously using this parameterization.

Fundamental estimation bounds for polarimetric imagery.

Precise channel-to-channel registration is a prerequisite for effective exploitation of passive polarimetric imagery. In this paper, the Cramer-Rao bound is employed to determine the limits of registration precision in the presence of scene polarization diversity, channel noise, and random translational registration errors between channels. The effects of misregistration on Stokes image estimation are also explored in depth.