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Hoehler MS, Chernovsky A, Bundy MF, Baumann E. Coherent Laser Ranging of Deforming Objects in Fires at Sub-Millimeter Precision. FIRE SAFETY JOURNAL 2023; 140:10.1016/j.firesaf.2023.103864. [PMID: 37719796 PMCID: PMC10501152 DOI: 10.1016/j.firesaf.2023.103864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Light Detection and Ranging (LiDAR) is a powerful tool to characterize and track the surface geometry of solid objects. In a fire, however, no method has excelled at measuring three-dimensional shapes at millimeter precision while offering some immunity to the effects of flames. This paper applies coherent Frequency Modulated Continuous Wave Light Detection and Ranging to capture three-dimensional measurements of objects in fire at meters of stand-off distance. We demonstrate that despite the presence of natural gas flame depths up to 1.5 m obscuring the target, measurements with millimeter precision can be obtained. This is a significant improvement over previous work making the technique useful for many fire research applications. An approach to achieve sub-millimeter precision using spatial and temporal averaging during post-processing is presented. The technology is demonstrated in case studies of structural connection and vegetation response in fires.
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Affiliation(s)
- Matthew S Hoehler
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, USA
| | - Artur Chernovsky
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, USA
| | - Matthew F Bundy
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, USA
| | - Esther Baumann
- National Institute of Standards and Technology, 325 Broadway, Boulder, USA
- Department of Physics, University of Colorado Boulder, Boulder, USA
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2
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Debnath B, M S M, Dharmadhikari JA, Chaudhuri S, Philip R, Ramachandran H. Acousto-optic modulator-based improvement in imaging through scattering media. APPLIED OPTICS 2023; 62:6609-6613. [PMID: 37706792 DOI: 10.1364/ao.496770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 07/28/2023] [Indexed: 09/15/2023]
Abstract
Reduced visibility is a common problem when light traverses through a scattering medium, and it becomes difficult to identify an object in such scenarios. What we believe to be a novel proof-of-principle technique for improving image visibility based on the quadrature lock-in discrimination algorithm in which the demodulation is performed using an acousto-optic modulator is presented here. A significant improvement in image visibility is achieved using a series of frames. We have also performed systematic imaging by varying the camera parameters, such as exposure time, frame rate, and series length, to investigate their effect on enhancing image visibility.
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3
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Gröger A, Pedrini G, Claus D, Alekseenko I, Gloeckler F, Reichelt S. Advantages of holographic imaging through fog. APPLIED OPTICS 2023; 62:D68-D76. [PMID: 37132771 DOI: 10.1364/ao.478435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In this paper, we demonstrate digital holographic imaging through a 27-m-long fog tube filled with ultrasonically generated fog. Its high sensitivity makes holography a powerful technology for imaging through scattering media. With our large-scale experiments, we investigate the potential of holographic imaging for road traffic applications, where autonomous driving vehicles require reliable environmental perception in all weather conditions. We compare single-shot off-axis digital holography to conventional imaging (with coherent illumination) and show that holographic imaging requires 30 times less illumination power for the same imaging range. Our work includes signal-to-noise ratio considerations, a simulation model, and quantitative statements on the influence of various physical parameters on the imaging range.
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Abstract
The current state of the art of single-photon detectors operating in the mid-infrared wavelength range is reported in this review. These devices are essential for a wide range of applications, such as mid-infrared quantum communications, sensing, and metrology, which require detectors with high detection efficiency, low dark count rates, and low dead times. The technological challenge of moving from the well-performing and commercially available near-infrared single-photon detectors to mid-infrared detection is discussed. Different approaches are explored, spanning from the stoichiometric or geometric engineering of a large variety of materials for infrared applications to the exploitation of alternative novel materials and the implementation of proper detection schemes. The three most promising solutions are described in detail: superconductive nanowires, avalanche photodiodes, and photovoltaic detectors.
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5
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Guo H, Zhou H, Banerjee PP. Use of structured light in 3D reconstruction of transparent objects. APPLIED OPTICS 2022; 61:B314-B324. [PMID: 35201154 DOI: 10.1364/ao.444708] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
A simple non-interferometric incoherent light ray propagation model is introduced to perform three-dimensional profiling of transparent objects with typical thicknesses of the order of mm to cm by analyzing the distorted captured image behind the object. A two-dimensional cosine fringe is used as the incident reference image, whose periodicity is markedly altered by the shape of the object. By monitoring the local change in the period, the surface profile is simulated and optimized to achieve minimal error with experimental data and thus determine the final morphology. Our proposed method is simple, robust, straightforward, and single-shot, and can be used with coherent or incoherent illumination. Its feasibility for more complex applications is verified experimentally through rigorous error calculation. Moreover, the application of this technique for arbitrary transparent objects is theoretically attainable and promising.
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Kang M, Woo S, Choi W, Kang P, Hoang TD, Koo J, Choi Y, Choi W. Single-shot multiple-depth macroscopic imaging by spatial frequency multiplexing. OPTICS EXPRESS 2021; 29:34360-34369. [PMID: 34809228 DOI: 10.1364/oe.439166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 09/27/2021] [Indexed: 06/13/2023]
Abstract
We present a low-coherence interferometric imaging system designed for 3-dimensional (3-D) imaging of a macroscopic object through a narrow passage. Our system is equipped with a probe-type port composed of a bundle fiber for imaging and a separate multimode optical fiber for illumination. To eliminate the need for mechanical depth scanning, we employ a spatial frequency multiplexing method by installing a 2-D diffraction grating and an echelon in the reference arm. This configuration generates multiple reference beams, all having different path lengths and propagation directions, which facilitates the encoding of different depth information in a single interferogram. We demonstrate the acquisition of 9 depth images at the interval of 250 μm for a custom-made cone and a plaster teeth model. The proposed system minimizes the need for mechanical scanning and achieves a wide range of depth coverage, significantly increasing the speed of 3-D imaging for macroscopic objects.
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Zhang H, Liu S, Cao L, Brady DJ. Noise suppression for ballistic-photons based on compressive in-line holographic imaging through an inhomogeneous medium. OPTICS EXPRESS 2020; 28:10337-10349. [PMID: 32225621 DOI: 10.1364/oe.385992] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/19/2020] [Indexed: 06/10/2023]
Abstract
Noise suppression is one of the most important tasks in imaging through inhomogeneous mediums. Here, we proposed a denoising approach based on compressive in-line holography for imaging through an inhomogeneous medium. A reference-beam-free system with a low-cost continuous-wave laser is presented. The suppression against the noise, which is brought by the scattering photons, is presented in simulations using the proposed algorithm. The noise immunity is demonstrated in lensless imaging behind a random phase mask with an optical depth of 1.42 by single exposure, as well as behind a ground glass with an optical depth of 6.38 by multiple exposures.
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Oscurato SL, Salvatore M, Borbone F, Maddalena P, Ambrosio A. Computer-generated holograms for complex surface reliefs on azopolymer films. Sci Rep 2019; 9:6775. [PMID: 31043674 PMCID: PMC6494893 DOI: 10.1038/s41598-019-43256-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 04/15/2019] [Indexed: 12/30/2022] Open
Abstract
The light-driven superficial structuration observed on the surface of films of azobenzene-containing polymers follows the optical field distribution of the illuminating light pattern, i.e. the light polarization state and the intensity distribution. The ability to precisely manipulate the illuminating intensity pattern can hence provide a new level in the range of complex light-induced superficial textures accessible onto azopolymer film surfaces. In this respect, digital holography, based on the principles of the Computer-Generated Holograms (CGHs), and actually implemented by means of a versatile liquid crystal spatial light modulator, can represent a unique experimental tool in the field of the light-induced mass migration in azo-materials. In the present work, we demonstrate the possibility to precisely control the features and the quality of complex light patterns generated through CGHs in order to induce arbitrarily complex surface reliefs onto the surface of an azopolymer. The results shown here can potentially broaden the range of possible applications of photo-responsive azopolymer films in the fields of surface engineering, biology and photonics.
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Affiliation(s)
- Stefano Luigi Oscurato
- Department of Physics "E. Pancini", University of Naples "Federico II", Complesso Universitario di Monte Sant'Angelo, Via Cintia, 80126, Naples, Italy
| | - Marcella Salvatore
- Department of Physics "E. Pancini", University of Naples "Federico II", Complesso Universitario di Monte Sant'Angelo, Via Cintia, 80126, Naples, Italy
| | - Fabio Borbone
- Department of Chemical Sciences, University of Naples "Federico II", Complesso Universitario di Monte Sant'Angelo, Via Cintia, 80126, Naples, Italy
| | - Pasqualino Maddalena
- Department of Physics "E. Pancini", University of Naples "Federico II", Complesso Universitario di Monte Sant'Angelo, Via Cintia, 80126, Naples, Italy
| | - Antonio Ambrosio
- Center for Nanoscale Systems, Harvard University, 9 Oxford Street, Cambridge, Massachusetts, 02138, United States.
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Li M, Chen X, Peng C, Du S, Li Y. Modeling the occlusion problem in thermal imaging to allow seeing through mist and foliage. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2019; 36:A67-A76. [PMID: 30874097 DOI: 10.1364/josaa.36.000a67] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 12/20/2018] [Indexed: 06/09/2023]
Abstract
Thermal imaging can easily see through smoke and dust. It is a useful technique in the military and industrial fields. However, thermal imaging can also be blocked by heavy mist or gases with high emissivity such as CO2. Allowing a thermal camera to see through these obstacles is in high demand. In this paper, we modeled the occlusion problem in thermal imaging and proposed an algorithm to image the objects through mist and foliage. We built a system to capture the thermal light field camera. We took thermal reflection and absorption of the obstacles into consideration. We removed the obstacle part in thermal images by estimating the intensity of infrared radiation. Then, we refocused the thermal images on the specific depth of the object for reconstruction. The experiment's results show that a proposed algorithm can reconstruct the occluded objects in a clear shape while blurring the obstacles. Based on the thermal occlusion model and refocusing, the thermal camera can image a human through mist and foliage.
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Donnarumma D, Rawat N, Brodoline A. High-speed quantitative 3D imaging by dual-illumination holographic microscopy. Microsc Res Tech 2018; 81:1361-1365. [PMID: 30431202 DOI: 10.1002/jemt.23076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 06/03/2018] [Indexed: 11/06/2022]
Abstract
A new blood flow imaging (BFI) technique using digital holography with double illumination of the sample is proposed. We imaged the moving red blood cells (RBCs) using a two microscope objective lenses setup. The setup consists in a larger angle of separation (90 °) between the two illumination beams, allowing a wider angular rotation at good z resolution. Moreover, the setup geometry allows an easier displacement of the sample in all directions. Results show that this technique is able to perform phase-shifting reconstruction for the two beams at the same time which is more suitable for the future implementation of live 3D holography. Experimental results are carried out for the verification of the effectiveness of the proposed technique on a zebrafish larvae sample. RESEARCH HIGHLIGHTS: Blood flow imaging techniques are often invasive and image analysis is time consuming. To alleviate this issue an imaging technique based on dual illumination in holographic domain is proposed. This method has been validated on zebrafish embryos.
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Affiliation(s)
- Dario Donnarumma
- Laboratoire Charles Coulomb - UMR 5221 CNRS-Université Montpellier, Place Eugène Bataillon, Montpellier, France
| | - Nitin Rawat
- Laboratoire Charles Coulomb - UMR 5221 CNRS-Université Montpellier, Place Eugène Bataillon, Montpellier, France
| | - Alexey Brodoline
- Laboratoire Charles Coulomb - UMR 5221 CNRS-Université Montpellier, Place Eugène Bataillon, Montpellier, France
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Bianco V, Memmolo P, Leo M, Montresor S, Distante C, Paturzo M, Picart P, Javidi B, Ferraro P. Strategies for reducing speckle noise in digital holography. LIGHT, SCIENCE & APPLICATIONS 2018; 7:48. [PMID: 30839600 PMCID: PMC6106996 DOI: 10.1038/s41377-018-0050-9] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 06/01/2018] [Accepted: 06/05/2018] [Indexed: 05/05/2023]
Abstract
Digital holography (DH) has emerged as one of the most effective coherent imaging technologies. The technological developments of digital sensors and optical elements have made DH the primary approach in several research fields, from quantitative phase imaging to optical metrology and 3D display technologies, to name a few. Like many other digital imaging techniques, DH must cope with the issue of speckle artifacts, due to the coherent nature of the required light sources. Despite the complexity of the recently proposed de-speckling methods, many have not yet attained the required level of effectiveness. That is, a universal denoising strategy for completely suppressing holographic noise has not yet been established. Thus the removal of speckle noise from holographic images represents a bottleneck for the entire optics and photonics scientific community. This review article provides a broad discussion about the noise issue in DH, with the aim of covering the best-performing noise reduction approaches that have been proposed so far. Quantitative comparisons among these approaches will be presented.
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Affiliation(s)
- Vittorio Bianco
- CNR-ISASI Istituto di Scienze Applicate e Sistemi Intelligenti “E. Caianiello”, via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Pasquale Memmolo
- CNR-ISASI Istituto di Scienze Applicate e Sistemi Intelligenti “E. Caianiello”, via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Marco Leo
- CNR-ISASI Istituto di Scienze Applicate e Sistemi Intelligenti “E. Caianiello”, via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Silvio Montresor
- Université du Maine, CNRS UMR 6613, LAUM, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
| | - Cosimo Distante
- CNR-ISASI Istituto di Scienze Applicate e Sistemi Intelligenti “E. Caianiello”, via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Melania Paturzo
- CNR-ISASI Istituto di Scienze Applicate e Sistemi Intelligenti “E. Caianiello”, via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Pascal Picart
- Université du Maine, CNRS UMR 6613, LAUM, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
| | - Bahram Javidi
- Electrical and Computer Engineering Department, University of Connecticut, U-4157, Storrs, CT 06269 USA
| | - Pietro Ferraro
- CNR-ISASI Istituto di Scienze Applicate e Sistemi Intelligenti “E. Caianiello”, via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
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Bianco V, Memmolo P, Paturzo M, Ferraro P. On-speckle suppression in IR digital holography. OPTICS LETTERS 2016; 41:5226-5229. [PMID: 27842099 DOI: 10.1364/ol.41.005226] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Long-IR wavelength is the best option for capturing digital holograms of large-size, real-world objects. However, the coherent noise level in a long-IR hologram is by far larger than that of a visible wavelength recording, thus resulting in a poor quality of both numerical and optical reconstructions. In this Letter, we show how such coherent noise can be efficiently suppressed by employing an optical scanning multi-look approach, in combination with 3D block matching numerical filtering. Results demonstrate the possibility to obtain near noise-free numerical reconstructions of IR digital holograms of large-size objects, while preserving resolution. We applied this method to the holograms of a rotating statuette. It will be shown that a remarkable contrast enhancement is achievable along with the recovery of object details that otherwise would be lost because of large speckle grains intrinsically due to the source coherence.
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Kurbatova EA, Cheremkhin PA, Evtikhiev NN. Methods of compression of digital holograms, based on 1-level wavelet transform. ACTA ACUST UNITED AC 2016. [DOI: 10.1088/1742-6596/737/1/012071] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Bianco V, Memmolo P, Paturzo M, Finizio A, Javidi B, Ferraro P. Quasi noise-free digital holography. LIGHT, SCIENCE & APPLICATIONS 2016; 5:e16142. [PMID: 30167185 PMCID: PMC6059929 DOI: 10.1038/lsa.2016.142] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 03/21/2016] [Accepted: 03/27/2016] [Indexed: 05/05/2023]
Abstract
One of the main drawbacks of Digital Holography (DH) is the coherent nature of the light source, which severely corrupts the quality of holographic reconstructions. Although numerous techniques to reduce noise in DH have provided good results, holographic noise suppression remains a challenging task. We propose a novel framework that combines the concepts of encoding multiple uncorrelated digital holograms, block grouping and collaborative filtering to achieve quasi noise-free DH reconstructions. The optimized joint action of these different image-denoising methods permits the removal of up to 98% of the noise while preserving the image contrast. The resulting quality of the hologram reconstructions is comparable to the quality achievable with non-coherent techniques and far beyond the current state of art in DH. Experimental validation is provided for both single-wavelength and multi-wavelength DH, and a comparison with the most used holographic denoising methods is performed.
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Affiliation(s)
- Vittorio Bianco
- Institute of Applied Sciences and Intelligent Systems ”E. Caianiello”, Italian National Research Council (ISASI-CNR), Via Campi Flegrei 34, 80078, Pozzuoli (Napoli), Italy
| | - Pasquale Memmolo
- Institute of Applied Sciences and Intelligent Systems ”E. Caianiello”, Italian National Research Council (ISASI-CNR), Via Campi Flegrei 34, 80078, Pozzuoli (Napoli), Italy
- E-mail:
| | - Melania Paturzo
- Institute of Applied Sciences and Intelligent Systems ”E. Caianiello”, Italian National Research Council (ISASI-CNR), Via Campi Flegrei 34, 80078, Pozzuoli (Napoli), Italy
| | - Andrea Finizio
- Institute of Applied Sciences and Intelligent Systems ”E. Caianiello”, Italian National Research Council (ISASI-CNR), Via Campi Flegrei 34, 80078, Pozzuoli (Napoli), Italy
| | - Bahram Javidi
- ECE Department, University of Connecticut, U-157, Storrs, Connecticut, 06269, USA
| | - Pietro Ferraro
- Institute of Applied Sciences and Intelligent Systems ”E. Caianiello”, Italian National Research Council (ISASI-CNR), Via Campi Flegrei 34, 80078, Pozzuoli (Napoli), Italy
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Cheremkhin PA, Evtikhiev NN, Krasnov VV, Kulakov MN, Kurbatova EA, Molodtsov DY, Rodin VG. Demonstration of digital hologram recording and 3D-scenes reconstruction in real-time. ACTA ACUST UNITED AC 2016. [DOI: 10.1117/12.2227767] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Sudarsanam S, Mathew J, Panigrahi S, Fade J, Alouini M, Ramachandran H. Real-time imaging through strongly scattering media: seeing through turbid media, instantly. Sci Rep 2016; 6:25033. [PMID: 27114106 PMCID: PMC4844949 DOI: 10.1038/srep25033] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/04/2016] [Indexed: 11/25/2022] Open
Abstract
Numerous everyday situations like navigation, medical imaging and rescue operations require viewing through optically inhomogeneous media. This is a challenging task as photons propagate predominantly diffusively (rather than ballistically) due to random multiple scattering off the inhomogenieties. Real-time imaging with ballistic light under continuous-wave illumination is even more challenging due to the extremely weak signal, necessitating voluminous data-processing. Here we report imaging through strongly scattering media in real-time and at rates several times the critical flicker frequency of the eye, so that motion is perceived as continuous. Two factors contributed to the speedup of more than three orders of magnitude over conventional techniques - the use of a simplified algorithm enabling processing of data on the fly, and the utilisation of task and data parallelization capabilities of typical desktop computers. The extreme simplicity of the technique, and its implementation with present day low-cost technology promises its utility in a variety of devices in maritime, aerospace, rail and road transport, in medical imaging and defence. It is of equal interest to the common man and adventure sportsperson like hikers, divers, mountaineers, who frequently encounter situations requiring realtime imaging through obscuring media. As a specific example, navigation under poor visibility is examined.
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Affiliation(s)
| | - James Mathew
- Raman Research Institute, Sadashiv Nagar, Bangalore, 560080, India
| | - Swapnesh Panigrahi
- Institut de Physique de Rennes, Universite de Rennes 1 CNRS, Campus de Beaulieu, 35042 Rennes, France
| | - Julien Fade
- Institut de Physique de Rennes, Universite de Rennes 1 CNRS, Campus de Beaulieu, 35042 Rennes, France
| | - Mehdi Alouini
- Institut de Physique de Rennes, Universite de Rennes 1 CNRS, Campus de Beaulieu, 35042 Rennes, France
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Remote monitoring of building oscillation modes by means of real-time Mid Infrared Digital Holography. Sci Rep 2016; 6:23688. [PMID: 27032810 PMCID: PMC4817048 DOI: 10.1038/srep23688] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 02/08/2016] [Indexed: 11/30/2022] Open
Abstract
Non-destructive measurements of deformations are a quite common application of holography but due to the intrinsic limits in the interferometric technique, those are generally confined only to small targets and in controlled environment. Here we present an advanced technique, based on Mid Infrared Digital Holography (MIR DH), which works in outdoor conditions and provides remote and real-time information on the oscillation modes of large engineering structures. Thanks to the long wavelength of the laser radiation, large areas of buildings can be simultaneously mapped with sub-micrometric resolution in terms of their amplitude and frequency oscillation modes providing all the modal parameters vital for all the correct prevention strategies when the functionality and the health status of the structures have to be evaluated. The existing experimental techniques used to evaluate the fundamental modes of a structure are based either on seismometric sensors or on Ground-based Synthetic Aperture Radar (GbSAR). Such devices have both serious drawbacks, which prevent their application at a large scale or in the short term. We here demonstrate that the MIR DH based technique can fully overcome these limitations and has the potential to represent a breakthrough advance in the field of dynamic characterization of large structures.
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18
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Lev A, Sfez B. Acousto-optical detection of hidden objects via speckle based imaging. OPTICS EXPRESS 2015; 23:26460-26471. [PMID: 26480159 DOI: 10.1364/oe.23.026460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Optical detection of objects hidden behind opaque screening layers is a challenging problem. We demonstrate an optically detected echographic-like method that combines collimated acoustic and laser beams. The acoustic waves cross the screening layers, and their back-reflection from the hidden objects is detected through the analysis of a dynamic laser speckle pattern created at the outer surface of the screening layer. Real-time remote detection of moving targets 15 meters away, with a few mm resolution is demonstrated using a very sensitive camera detection scheme.
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Bianco V, Paturzo M, Finizio A, Stetson KA, Ferraro P. Portable IR Laser System for Real-Time Display of Alive People in Fire Scenes. ACTA ACUST UNITED AC 2015. [DOI: 10.1109/jdt.2014.2381366] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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20
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Real-time terahertz digital holography with a quantum cascade laser. Sci Rep 2015; 5:13566. [PMID: 26315647 PMCID: PMC4551990 DOI: 10.1038/srep13566] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 07/30/2015] [Indexed: 11/08/2022] Open
Abstract
Coherent imaging in the THz range promises to exploit the peculiar capabilities of these wavelengths to penetrate common materials like plastics, ceramics, paper or clothes with potential breakthroughs in non-destructive inspection and quality control, homeland security and biomedical applications. Up to now, however, THz coherent imaging has been limited by time-consuming raster scanning, point-like detection schemes and by the lack of adequate coherent sources. Here, we demonstrate real-time digital holography (DH) at THz frequencies exploiting the high spectral purity and the mW output power of a quantum cascade laser combined with the high sensitivity and resolution of a microbolometric array. We show that, in a one-shot exposure, phase and amplitude information of whole samples, either in reflection or in transmission, can be recorded. Furthermore, a 200 times reduced sensitivity to mechanical vibrations and a significantly enlarged field of view are observed, as compared to DH in the visible range. These properties of THz DH enable unprecedented holographic recording of real world dynamic scenes.
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Jiang Z, Veetil SP, Cheng J, Liu C, Wang L, Zhu J. High-resolution digital holography with the aid of coherent diffraction imaging. OPTICS EXPRESS 2015; 23:20916-20925. [PMID: 26367944 DOI: 10.1364/oe.23.020916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The image reconstructed in ordinary digital holography was unable to bring out desired resolution in comparison to photographic materials; thus making it less preferable for many interesting applications. A method is proposed to enhance the resolution of digital holography in all directions by placing a random phase plate between the specimen and the electronic camera and then using an iterative approach to do the reconstruction. With this method, the resolution is improved remarkably in comparison to ordinary digital holography. Theoretical analysis is supported by numerical simulation. The feasibility of the method is also studied experimentally.
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Jiang Z, Veetil SP, Liu C, Zhu J. Depth resolved imaging by digital holography with an illumination of constantly changing curvature. OPTICS LETTERS 2015; 40:3001-3004. [PMID: 26125352 DOI: 10.1364/ol.40.003001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this Letter, a single wavelength digital holographic method is proposed to achieve depth resolved imaging by recording a series of holograms in the reflection geometry with an illumination of constantly changing curvature. A proper algorithm is employed to selectively generate the images of the object at different depths, including the phase and the modulus information. Theoretical analysis is supported by a visible light experiment to illustrate the feasibility of the proposed method.
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Sui X, Zeng J, Chen Q, Gu G. High spatial resolution recording of near-infrared hologram based on photo-induced phase transition of vanadium dioxide film. OPTICS LETTERS 2015; 40:1595-1598. [PMID: 25831393 DOI: 10.1364/ol.40.001595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present a method to record near-infrared (NIR) hologram at high spatial resolution. This method up-converts the NIR holograms to visible holograms taking advantage of the photo-induced phase transition characteristic of vanadium dioxide (VO2) material, and subsequently, the visible holograms are recorded by a high-resolution visible CMOS sensor. Obviously the pitch of visible sensor is much smaller than NIR sensors, so our method can extremely increase the recording resolution of NIR holograms. The experiments demonstrate the effectiveness of our method. Our method can improve the viewing angle of NIR holography to observe large-scale objects and shorten the observation distance so that the application area of NIR holography is expanded. It has the potential to become a more effective NIR hologram recording method.
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Kurbatova E, Cheremkhin P, Evtikhiev N, Krasnov V, Starikov S. Methods of Compression of Digital Holograms. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.phpro.2015.09.150] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Desse JM, Picart P. Stochastic digital holography for visualizing inside strongly refracting transparent objects. APPLIED OPTICS 2015; 54:A1-A8. [PMID: 25967016 DOI: 10.1364/ao.54.0000a1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 10/06/2014] [Indexed: 06/04/2023]
Abstract
This paper presents a digital holographic method to visualize and measure refractive index variations, convection currents, or thermal gradients, occurring inside a transparent and refracting object. The proof of principle is provided through the visualization of refractive index variation inside a lighting bulb. Comparison with transmission and reflection holography is also provided. A very good agreement is obtained, thus validating the proposed approach.
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Georges MP, Vandenrijt JF, Thizy C, Alexeenko I, Pedrini G, Vollheim B, Lopez I, Jorge I, Rochet J, Osten W. Combined holography and thermography in a single sensor through image-plane holography at thermal infrared wavelengths. OPTICS EXPRESS 2014; 22:25517-25529. [PMID: 25401585 DOI: 10.1364/oe.22.025517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Holographic interferometry in the thermal wavelengths range, combining a CO(2) laser and digital hologram recording with a microbolometer array based camera, allows simultaneously capturing temperature and surface shape information about objects. This is due to the fact that the holograms are affected by the thermal background emitted by objects at room temperature. We explain the setup and the processing of data which allows decoupling the two types of information. This natural data fusion can be advantageously used in a variety of nondestructive testing applications.
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Memmolo P, Bianco V, Paturzo M, Javidi B, Netti PA, Ferraro P. Encoding multiple holograms for speckle-noise reduction in optical display. OPTICS EXPRESS 2014; 22:25768-25775. [PMID: 25401610 DOI: 10.1364/oe.22.025768] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In digital holography (DH) a mixture of speckle and incoherent additive noise, which appears in numerical as well as in optical reconstruction, typically degrades the information of the object wavefront. Several methods have been proposed in order to suppress the noise contributions during recording or even during the reconstruction steps. Many of them are based on the incoherent combination of multiple holographic reconstructions achieving remarkable improvement, but only in the numerical reconstruction i.e. visualization on a pc monitor. So far, it has not been shown the direct synthesis of a digital hologram which provides the denoised optical reconstruction. Here, we propose a new effective method for encoding in a single complex wavefront the contribution of multiple incoherent reconstructions, thus allowing to obtain a single synthetic digital hologram that show significant speckle-reduction when optically projected by a Spatial Light Modulator (SLM).
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Demoli N, Skenderović H, Stipčević M. Digital holography at light levels below noise using a photon-counting approach. OPTICS LETTERS 2014; 39:5010-5013. [PMID: 25166061 DOI: 10.1364/ol.39.005010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Recording of digital holograms of a weak signal [0.44 counts per second (cps)] hidden below the detector's noise (21 cps) is investigated by employing the high dynamic range of a photon-counting detector. Recording conditions are discussed in terms of the most important holographic measures, namely, the fringe visibility (or contrast) and signal-to-noise ratio (SNR), and in relation to the main holographic parameters. Theoretically evaluated curves are tested by recording holograms for a wide range of the parameter values. We found that (i) the optimum set of holographic parameters can be determined for a harsh signal conditions, (ii) increasing the visibility does not necessarily improve the more important SNR, and (iii) in cases of nearly constant visibility, the SNR clearly reveals differences in the quality of holographic recordings.
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Ravaro M, Locatelli M, Pugliese E, Di Leo I, Siciliani de Cumis M, D'Amato F, Poggi P, Consolino L, Meucci R, Ferraro P, De Natale P. Mid-infrared digital holography and holographic interferometry with a tunable quantum cascade laser. OPTICS LETTERS 2014; 39:4843-4846. [PMID: 25121889 DOI: 10.1364/ol.39.004843] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Mid-infrared digital holography based on CO2 lasers has proven to be a powerful coherent imaging technique due to reduced sensitivity to mechanical vibrations, increased field of view, high optical power, and possible vision through scattering media, e.g., smoke. Here we demonstrate a similar and more compact holographic system based on an external cavity quantum cascade laser emitting at 8 μm. Such a setup, which includes a highly sensitive microbolometric camera, allows the acquisition of speckle holograms of scattering objects, which can be processed in real time. In addition, by exploiting the broad laser tunability, we can acquire holograms at different wavelengths, from which we extract phase images not subjected to phase wrapping, at synthetic wavelengths ranging from hundreds of micrometers to several millimeters.
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Orabona E, Ambrosio A, Longo A, Carotenuto G, Nicolais L, Maddalena P. Holographic patterning of graphene-oxide films by light-driven reduction. OPTICS LETTERS 2014; 39:4263-4266. [PMID: 25121702 DOI: 10.1364/ol.39.004263] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report on the patterning and reduction of graphene-oxide films by holographic lithography. Light reduction can be used to engineer low-cost graphene-based devices by performing a local conversion of insulating oxide into the conductive graphene. In this work, computer-generated holograms have been exploited to realize complex graphene patterns in a single shot, different from serial laser writing or mask-based photolithographic processes. The technique has been further improved by achieving speckle noise reduction: submicron and diffraction-limited features have been obtained. In addition we have also demonstrated that the gray-scale lithography capability can be used to obtain different reduction levels in a single exposure.
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Bianco V, Paturzo M, Gennari O, Finizio A, Ferraro P. Imaging through scattering microfluidic channels by digital holography for information recovery in lab on chip. OPTICS EXPRESS 2013; 21:23985-23996. [PMID: 24104309 DOI: 10.1364/oe.21.023985] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We tackle the problem of information recovery and imaging through scattering microfluidic chips by means of digital holography (DH). In many cases the chip can become opalescent due to residual deposits settling down the inner channel faces, biofilm formation, scattering particle uptake by the channel cladding or its damaging by corrosive substances, or even by condensing effect on the exterior channels walls. In these cases white-light imaging is severely degraded and no information is obtainable at all about the flowing samples. Here we investigate the problem of counting and estimating velocity of cells flowing inside a scattering chip. Moreover we propose and test a method based on the recording of multiple digital holograms to retrieve improved phase-contrast images despite the strong scattering effect. This method helps, thanks to DH, to recover information which, otherwise, would be completely lost.
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Wang Y, Meng P, Wang D, Rong L, Panezai S. Speckle noise suppression in digital holography by angular diversity with phase-only spatial light modulator. OPTICS EXPRESS 2013; 21:19568-19578. [PMID: 24105504 DOI: 10.1364/oe.21.019568] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A speckle noise suppression method in digital holography is proposed by the angular diversity with a phase-only spatial light modulator (SLM). The minimal angular difference of illumination beams is quantitatively analyzed to ensure the noncorrelation of any two speckle patterns, and then the phase-only SLM is employed to generate a series of tilted illumination beams. Comparing with the typical methods, the tilted illumination beams are controlled dynamically and accurately, which makes it possible to record a large number of holograms. Finally, using an image-plane digital holographic system, 117 holograms are recorded respectively, and the synthesized reconstructed images are obtained with the greatly suppressed speckle noise which is in good agreement with the theoretical results. The experimental results demonstrate the effectiveness, repeatability, and practicability of the proposed approach.
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