Lensless coded-aperture imaging with separable Doubly-Toeplitz masks

Michael J. DeWeert; Brian P. Farm

doi:10.1117/1.OE.54.2.023102

3 February 2015 Lensless coded-aperture imaging with separable Doubly-Toeplitz masks

Michael J. DeWeert, Brian P. Farm

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Optical Engineering, Vol. 54, Issue 2, 023102 (February 2015). https://doi.org/10.1117/1.OE.54.2.023102

Abstract

In certain imaging applications, conventional lens technology is constrained by the lack of materials which can effectively focus the radiation within a reasonable weight and volume. One solution is to use coded apertures—opaque plates perforated with multiple pinhole-like openings. If the openings are arranged in an appropriate pattern, then the images can be decoded and a clear image computed. Recently, computational imaging and the search for a means of producing programmable software-defined optics have revived interest in coded apertures. The former state-of-the-art masks, modified uniformly redundant arrays (MURAs), are effective for compact objects against uniform backgrounds, but have substantial drawbacks for extended scenes: (1) MURAs present an inherently ill-posed inversion problem that is unmanageable for large images, and (2) they are susceptible to diffraction: a diffracted MURA is no longer a MURA. We present a new class of coded apertures, separable Doubly-Toeplitz masks, which are efficiently decodable even for very large images—orders of magnitude faster than MURAs, and which remain decodable when diffracted. We implemented the masks using programmable spatial-light-modulators. Imaging experiments confirmed the effectiveness of separable Doubly-Toeplitz masks—images collected in natural light of extended outdoor scenes are rendered clearly.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Michael J. DeWeert and Brian P. Farm "Lensless coded-aperture imaging with separable Doubly-Toeplitz masks," Optical Engineering 54(2), 023102 (3 February 2015). https://doi.org/10.1117/1.OE.54.2.023102

Published: 3 February 2015

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