362,290 research outputs found
Computational Ghost Imaging
Ghost-imaging experiments correlate the outputs from two photodetectors: a
high spatial-resolution (scanning pinhole or CCD camera) detector that measures
a field which has not interacted with the object to be imaged, and a bucket
(single-pixel) detector that collects a field that has interacted with the
object. We describe a computational ghost-imaging arrangement that uses only a
single-pixel detector. This configuration affords background-free imagery in
the narrowband limit and a 3D sectioning capability. It clearly indicates the
classical nature of ghost-image formation.Comment: 4 pages, 3 figure
Computational polarimetric microwave imaging
We propose a polarimetric microwave imaging technique that exploits recent
advances in computational imaging. We utilize a frequency-diverse cavity-backed
metasurface, allowing us to demonstrate high-resolution polarimetric imaging
using a single transceiver and frequency sweep over the operational microwave
bandwidth. The frequency-diverse metasurface imager greatly simplifies the
system architecture compared with active arrays and other conventional
microwave imaging approaches. We further develop the theoretical framework for
computational polarimetric imaging and validate the approach experimentally
using a multi-modal leaky cavity. The scalar approximation for the interaction
between the radiated waves and the target---often applied in microwave
computational imaging schemes---is thus extended to retrieve the susceptibility
tensors, and hence providing additional information about the targets.
Computational polarimetry has relevance for existing systems in the field that
extract polarimetric imagery, and particular for ground observation. A growing
number of short-range microwave imaging applications can also notably benefit
from computational polarimetry, particularly for imaging objects that are
difficult to reconstruct when assuming scalar estimations.Comment: 17 pages, 15 figure
3D Computational Ghost Imaging
Computational ghost imaging retrieves the spatial information of a scene
using a single pixel detector. By projecting a series of known random patterns
and measuring the back reflected intensity for each one, it is possible to
reconstruct a 2D image of the scene. In this work we overcome previous
limitations of computational ghost imaging and capture the 3D spatial form of
an object by using several single pixel detectors in different locations. From
each detector we derive a 2D image of the object that appears to be illuminated
from a different direction, using only a single digital projector as
illumination. Comparing the shading of the images allows the surface gradient
and hence the 3D form of the object to be reconstructed. We compare our result
to that obtained from a stereo- photogrammetric system utilizing multiple high
resolution cameras. Our low cost approach is compatible with consumer
applications and can readily be extended to non-visible wavebands.Comment: 13pages, 4figure
Quantum-inspired computational imaging
Computational imaging combines measurement and computational methods with the aim of forming images even when the measurement conditions are weak, few in number, or highly indirect. The recent surge in quantum-inspired imaging sensors, together with a new wave of algorithms allowing on-chip, scalable and robust data processing, has induced an increase of activity with notable results in the domain of low-light flux imaging and sensing. We provide an overview of the major challenges encountered in low-illumination (e.g., ultrafast) imaging and how these problems have recently been addressed for imaging applications in extreme conditions. These methods provide examples of the future imaging solutions to be developed, for which the best results are expected to arise from an efficient codesign of the sensors and data analysis tools.Y.A. acknowledges support from the UK Royal Academy of Engineering under the Research Fellowship Scheme (RF201617/16/31). S.McL. acknowledges financial support from the UK Engineering and Physical Sciences Research Council (grant EP/J015180/1). V.G. acknowledges support from the U.S. Defense Advanced Research Projects Agency (DARPA) InPho program through U.S. Army Research Office award W911NF-10-1-0404, the U.S. DARPA REVEAL program through contract HR0011-16-C-0030, and U.S. National Science Foundation through grants 1161413 and 1422034. A.H. acknowledges support from U.S. Army Research Office award W911NF-15-1-0479, U.S. Department of the Air Force grant FA8650-15-D-1845, and U.S. Department of Energy National Nuclear Security Administration grant DE-NA0002534. D.F. acknowledges financial support from the UK Engineering and Physical Sciences Research Council (grants EP/M006514/1 and EP/M01326X/1). (RF201617/16/31 - UK Royal Academy of Engineering; EP/J015180/1 - UK Engineering and Physical Sciences Research Council; EP/M006514/1 - UK Engineering and Physical Sciences Research Council; EP/M01326X/1 - UK Engineering and Physical Sciences Research Council; W911NF-10-1-0404 - U.S. Defense Advanced Research Projects Agency (DARPA) InPho program through U.S. Army Research Office; HR0011-16-C-0030 - U.S. DARPA REVEAL program; 1161413 - U.S. National Science Foundation; 1422034 - U.S. National Science Foundation; W911NF-15-1-0479 - U.S. Army Research Office; FA8650-15-D-1845 - U.S. Department of the Air Force; DE-NA0002534 - U.S. Department of Energy National Nuclear Security Administration)Accepted manuscrip
Computational temporal ghost imaging
Ghost imaging is a fascinating process, where light interacting with an
object is recorded without resolution, but the shape of the object is
nevertheless retrieved, thanks to quantum or classical correlations of this
interacting light with either a computed or detected random signal. Recently,
ghost imaging has been extended to a time object, by using several thousands
copies of this periodic object. Here, we present a very simple device, inspired
by computational ghost imaging, that allows the retrieval of a single
non-reproducible, periodic or non-periodic, temporal signal. The reconstruction
is performed by a single shot, spatially multiplexed, measurement of the
spatial intensity correlations between computer-generated random images and the
images, modulated by a temporal signal, recorded and summed on a chip CMOS
camera used with no temporal resolution. Our device allows the reconstruction
of either a single temporal signal with monochrome images or
wavelength-multiplexed signals with color images
Enhanced Computational Imaging for Microendoscopy
Microendoscope imaging systems suffer from high levels of aberrations, a narrow Field of View and short Depth of Field. We present a technique for enhanced imaging through a microendoscope using a novel computational imaging approach
Video-rate computational super-resolution and integral imaging at longwave-infrared wavelengths
We report the first computational super-resolved, multi-camera integral
imaging at long-wave infrared (LWIR) wavelengths. A synchronized array of FLIR
Lepton cameras was assembled, and computational super-resolution and
integral-imaging reconstruction employed to generate video with light-field
imaging capabilities, such as 3D imaging and recognition of partially obscured
objects, while also providing a four-fold increase in effective pixel count.
This approach to high-resolution imaging enables a fundamental reduction in the
track length and volume of an imaging system, while also enabling use of
low-cost lens materials.Comment: Supplementary multimedia material in
http://dx.doi.org/10.6084/m9.figshare.530302
Phaseless computational imaging with a radiating metasurface
Computational imaging modalities support a simplification of the active
architectures required in an imaging system and these approaches have been
validated across the electromagnetic spectrum. Recent implementations have
utilized pseudo-orthogonal radiation patterns to illuminate an object of
interest---notably, frequency-diverse metasurfaces have been exploited as fast
and low-cost alternative to conventional coherent imaging systems. However,
accurately measuring the complex-valued signals in the frequency domain can be
burdensome, particularly for sub-centimeter wavelengths. Here, computational
imaging is studied under the relaxed constraint of intensity-only measurements.
A novel 3D imaging system is conceived based on 'phaseless' and compressed
measurements, with benefits from recent advances in the field of phase
retrieval. In this paper, the methodology associated with this novel principle
is described, studied, and experimentally demonstrated in the microwave range.
A comparison of the estimated images from both complex valued and phaseless
measurements are presented, verifying the fidelity of phaseless computational
imaging.Comment: 18 pages, 18 figures, articl
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