Randomized apertures: high resolution imaging in far field: erratum.

We note a correction to Eq. (6) for [ Opt. Express25(15), 18296 (2017)].

Randomized apertures: high resolution imaging in far field.

We explore opportunities afforded by an extremely large telescope design comprised of ill-figured randomly varying subapertures. The veracity of this approach is demonstrated with a laboratory scaled system whereby we reconstruct a white light binary point source separated by 2.5 times the diffraction limit. With an inherently unknown varying random point spread function, the measured speckle images require a restoration framework that combine support vector machine based lucky imaging and non-negative matrix factorization based multiframe blind deconvolution. To further validate the approach, we model the experimental system to explore sub-diffraction-limited performance, and an object comprised of multiple point sources.

Low-angle optical vortex coronagraphic scatterometer.

The important, but difficult-to-measure zero and low-angle scattering spectrum, as well as the broader angular spectrum, was obtained by use of an optical vortex coronagraphic scatterometer (patent pending). The experimental measurements agreed well with the predictions from the Mie scattering theory. High contrast discrimination allowed us to remove the unscattered coherent illumination, revealing a low-angle superimposed scattered signal.

Reducing the risk of laser damage in a focal plane array using linear pupil-plane phase elements.

A compact imaging system with reduced risk of damage owing to intense laser radiation is presented. We find that a pupil phase element may reduce the peak image plane irradiance from an undesirable laser source by two orders of magnitude, thereby protecting the detector from damage. The desired scene is reconstructed in postprocessing. The general image quality equation (GIQE) [Appl. Opt.36, 8322 (1997)] is used to estimate the interpretability of the resulting images. A localized loss of information caused by laser light is also described. This system may be advantageous over other radiation protection approaches because accurate pointing and nonlinear materials are not required.

Vortex-phase filtering technique for extracting spatial information from unresolved sources.

A white light vortex coronagraph was used to experimentally achieve sub-resolution detection. The angular location of the centroid γ, and the angular extent of circular pinhole sources Θ, were measured to within errors of δγ=±0.015λ/D and δΘ=±0.026λ/D. This technique has two advantages over conventional imaging: simple power measurements are made and shorter exposure times may be required to achieve a sufficient signal-to-noise ratio.

Optical vortex coronagraphy with an elliptical aperture.

An optical vortex coronagraph that makes efficient use of a larger fraction of the clear aperture of a Cassegrain-type telescope is described. This design incorporates an elliptical subaperture rather than the conventional circular subaperture. We derive a new vortex phase mask that maintains the same theoretical contrast of a circularly symmetric vortex coronagraph.