The diffractive plenoptic camera (DPC) was developed as a system that would capture the spectral and spatial information of a scene in one snapshot. While the DPC couples a diffractive optic with plenoptic camera designs to provide snapshot spectral imaging capabilities, it produces rendered images with low pixel count and low spatial resolution. A modified setup of the DPC, the intermediate image (II)DPC, was built and tested for the first time and compared to both the DPC and a diffractive-optic camera as a system that could improve the cutoff spatial frequency of the rendered images. This paper reports on the spatial resolution achieved for different configurations of the IIDPC and looks at the factors limiting performance. The IIDPC improved on the cutoff spatial resolution over the DPC over a wavelength range of 750 to 790 nm for a design wavelength of 770 nm and improved resolution over a diffractive-optic camera at wavelengths below 750 nm or above 790 nm, with the best results achieved for IIDPC configurations with the largest magnification. Frequency analysis of each system determined that the optic limiting performance was the microlens array. Models showed that decreasing the microlens size improved resolution but reduced the spectral range for the DPC, while decreasing the f  /  # of the microlenses improved the resolution for the IIDPC. These results will help optimize the designs of future systems.

Efforts to extend speckle-based focal plane array modulation transfer function measurements beyond the detector Nyquist frequency have unearthed challenging spectral estimation issues. In an attempt to better understand the task of speckle imagery spectral estimation, we explore 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 from this research show the advantage increasing the number of realizations has on estimation variance, the robustness of smaller realization segments when battling speckle field imagery spatial nonuniformities, the benefits of windowing image segments with regard to power spectral density estimation accuracy, and the impact that the increasing aperture area has on system signal-to-noise ratio.