Papers by Francesco Di Lena
Quantum Communications and Quantum Imaging XX
Quantum Communications and Quantum Imaging XX
We review the advancement of the research toward the design and implementation of quantum plenopt... more We review the advancement of the research toward the design and implementation of quantum plenoptic cameras, radically novel 3D imaging devices that exploit both momentumposition entanglement and photon-number correlations to provide the typical refocusing and ultra-fast, scanning-free, 3D imaging capability of plenoptic devices, along with dramatically enhanced performances, unattainable in standard plenoptic cameras: diffraction-limited resolution, large depth of focus, and ultra-low noise. To further increase the volumetric resolution beyond the Rayleigh diffraction limit, and achieve the quantum limit, we are also developing dedicated protocols based on quantum Fisher information. However, for the quantum advantages of the proposed devices to be effective and appealing to end-users, two main challenges need to be tackled. First, due to the large number of frames required for correlation measurements to provide an acceptable SNR, quantum plenoptic imaging would require, if implemented with commercially available high-resolution cameras, acquisition times ranging from tens of seconds to a few minutes. Second, the elaboration of this large amount of data, in order to retrieve 3D images or refocusing 2D images, requires highperformance and time-consuming computation. To address these challenges, we are developing high-resolution SPAD arrays and high-performance low-level programming of ultra-fast electronics, combined with compressive sensing and quantum tomography algorithms, with the aim to reduce both the acquisition and the elaboration time by two orders of magnitude. Routes toward exploitation of the QPI devices will also be discussed.
Sensors
Diffraction-limited light-field imaging has been recently achieved by exploiting light spatial co... more Diffraction-limited light-field imaging has been recently achieved by exploiting light spatial correlations measured on two high-resolution detectors. As in conventional light-field imaging, the typical operations of refocusing and 3D reconstruction are based on ray tracing in a geometrical optics context, and are thus well defined in the ideal case, both conceptually and theoretically. However, some properties of the measured correlation function are influenced by experimental features such as the finite size of apertures, detectors, and pixels. In this work, we take into account realistic experimental conditions and analyze the resulting correlation function through theory and simulation. We also provide an expression to evaluate the pixel-limited resolution of the refocused images, as well as a strategy for eliminating artifacts introduced by the finite size of the optical elements.
Quantum Communications and Quantum Imaging XVIII, 2020
CPI is a novel imaging modality capable of addressing the intrinsic limitations of conventional p... more CPI is a novel imaging modality capable of addressing the intrinsic limitations of conventional plenoptic imaging - namely, the resolution loss and the sacrificed change of perspective, - while guaranteeing the typical advantages of plenotpic imaging: 3D imaging, refocusing of acquired pictures, in post-processing, and depth of field extension. In this work, we review a recently developed CPI scheme, named correlation plenoptic imaging between arbitrary planes and derive the algorithm for image refocusing.
Quantum Information and Measurement (QIM) V: Quantum Technologies, 2019
Imaging and Applied Optics 2018 (3D, AO, AIO, COSI, DH, IS, LACSEA, LS&C, MATH, pcAOP), 2018
We demonstrate, theoretically and experimentally, the possibility to perform plenoptic imaging by... more We demonstrate, theoretically and experimentally, the possibility to perform plenoptic imaging by measuring intensity correlations of light. Unlike standard plenoptic procedures, the technique we propose does not sacrifice spatial resolution to achieve directional resolution.
Unconventional Optical Imaging, 2018
One of the most peculiar features of imaging systems is the trade-off between resolution and dept... more One of the most peculiar features of imaging systems is the trade-off between resolution and depth of field. Resolution can be improved by increasing the numerical aperture of the imaging system. However, the range of distances that can be put in sharp focus in a single shot decreases with the square of the numerical aperture. Plenoptic imaging (PI) devices are able to retrieve both spatial and directional information from the scene of interest, usually by placing a microlens array in front of the camera sensor. This feature entails the possibility to refocusing planes of the scene in a much wider range than the natural depth of field of the system, and also to change the point of view on the scene. Though plenoptic imaging is one of the most promising techniques for 3D imaging, its advantages come at the expense of spatial resolution, which can no longer reach the diffraction limit. We experimentally demonstrate that correlations of chaotic light can be exploited to overcome the inverse proportionality between depth of field and resolution, and perform plenoptic imaging at the diffraction limit. We retrieve images by correlating intensity fluctuations at different points of two parts of a sensor, which register spatial and angular information, respectively. Hence, our Correlation Plenoptic Imaging (CPI) protocol does not add any limitation to the native resolution of the imaging system. We show the experimental refocusing, through the CPI procedure, of widely out-of-focus parts of a transmissive test target. Moreover, we determine and test the theoretical limits of CPI in terms of resolution and depth of field, quantifying the improvement with respect to standard imaging and classical PI. We finally comment on future perspectives.
Photonics for Quantum, 2021
We present a new technique for performing three-dimensional optical microscopy based on correlati... more We present a new technique for performing three-dimensional optical microscopy based on correlation plenoptic imaging. This approach, named Correlation Plenoptic Microscopy (CPM), exploits correlations between intensity fluctuations of pseudo-thermal light to retrieve plenoptic information about the sample, i. e. both spatial information about the intensity distribution of light and angular information about the propagation direction of the light rays. This leads to an enhancement of the depth of field, overcoming the sacrifice of lateral resolution required in conventional plenoptic microscopy. The intrinsic capability to refocus out-of-focus planes of the sample enables scanning-free three-dimensional reconstruction with the resolution kept at the diffraction limit. We show a setup to perform CPM with a microscope objective and present calculations of the correlation function for this specific case. Moreover we demonstrate with simulations that CPM improves the resolution, for a given depth of field, with respect to conventional optical microscopy.
Imaging aims to create a correspondence between the distribution of light in an object plane, in ... more Imaging aims to create a correspondence between the distribution of light in an object plane, in which the objects of interest are placed, and in an image plane, where a sensor measures intensity. An imaging device is characterized by resolution, which determines how sharp is the correspondence between the two conjugate planes, and depth of field, which fixes the longitudinal distance range in which the object can move, while its image is still well focused on the sensor. Unfortunately, a natural tradeoff between resolution and depth of field entails that focusing a high-resolution image is much harder than focusing a low-resolution one. Moreover, standard imaging devices are not able to recover information on the out-of-focus planes after the acquisition. The goal of plenoptic imaging is to overcome this limitation, by retrieving combined information on both the spatial distribution and the direction of light in the scene of interest, which opens the possibility to refocus planes o...
(1)(2) (*) on behalf of F. V. Pepe(2), A. Mazzilli(1), A. Garuccio(1)(2)(3), G. Scarcelli(4) and ... more (1)(2) (*) on behalf of F. V. Pepe(2), A. Mazzilli(1), A. Garuccio(1)(2)(3), G. Scarcelli(4) and M. D'Angelo(1)(2)(3)
Biophotonics Congress 2021, 2021
Lightfield imaging is an inspiring modality for high speed volumetric imaging; however, in its co... more Lightfield imaging is an inspiring modality for high speed volumetric imaging; however, in its conventional implementation, resolution is inherently low. We demonstrate diffraction-limited extended volumetric imaging by a lightfield microscope exploiting spatio-temporal correlations of light.
OSA Imaging and Applied Optics Congress 2021 (3D, COSI, DH, ISA, pcAOP), 2021
Light-field imaging is an inspiring modality for high-speed volumetric imaging We demonstrate dif... more Light-field imaging is an inspiring modality for high-speed volumetric imaging We demonstrate diffraction-limited extended volumetric imaging by a light-field microscope exploiting spatio-temporal correlations of light, overcoming the resolution limitations of conventional implementations of light-field imaging.
Quantum Communications and Quantum Imaging XIX, 2021
We present novel methods to perform plenoptic imaging at the diffraction limit by measuring inten... more We present novel methods to perform plenoptic imaging at the diffraction limit by measuring intensity correlations of light. The first method is oriented towards plenoptic microscopy, a promising technique which allows refocusing and depth-of-field enhancement, in post-processing, as well as scanning free 3D imaging. To overcome the limitations of standard plenoptic microscopes, we propose an adaptation of Correlation Plenoptic Imaging (CPI) to the working conditions of microscopy. We consider and compare different architectures of CPI microscopes, and discuss the improved robustness with respect to previous protocols against turbulence around the sample. The second method is based on measuring correlations between the images of two reference planes, arbitrarily chosen within the tridimensional scene of interest, providing an unprecedented combination of image resolution and depth of field. The results lead the way towards the realization of compact designs for CPI devices.
Optics Express, 2020
We propose a novel method to perform plenoptic imaging at the diffraction limit by measuring seco... more We propose a novel method to perform plenoptic imaging at the diffraction limit by measuring second-order correlations of light between two reference planes, arbitrarily chosen, within the tridimensional scene of interest. We show that for both chaotic light and entangled-photon illumination, the protocol enables to change the focused planes, in post-processing, and to achieve an unprecedented combination of image resolution and depth of field. In particular, the depth of field results larger by a factor 3 with respect to previous correlation plenoptic imaging protocols, and by an order of magnitude with respect to standard imaging, while the resolution is kept at the diffraction limit. The results lead the way towards the development of compact designs for correlation plenoptic imaging devices based on chaotic light, as well as high-SNR plenoptic imaging devices based on entangled photon illumination, thus contributing to make correlation plenoptic imaging effectively competitive w...
Photonics for Quantum, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Physics Letters A, 2020
Abstract Plenoptic microscopy is a promising technique which allows refocusing and depth-of-field... more Abstract Plenoptic microscopy is a promising technique which allows refocusing and depth-of-field enhancement, in post-processing, as well as scanning free 3D imaging. However, in its conventional implementation, spatial resolution is highly sacrificed and cannot reach the diffraction limit set by the numerical aperture of the imaging system. We recently proposed a novel method, named Correlation Plenoptic Imaging (CPI), based on measuring intensity correlation of either chaotic or entangled photon light sources. However, such protocols are not well suited for microscopic purposes: they cannot be employed with scattering or fluorescent samples and are extremely sensitive to diffusive effects. Here we consider and compare novel CPI protocols which overcome these problems and enable to perform plenoptic microscopy at the diffraction limit for generic samples; we present both theory and simulations, discuss the improved robustness with respect to previous protocols against turbulence around the sample, and highlight the physical limits of the proposed technique.
International Journal of Quantum Information, 2020
Sub-shot-noise imaging and correlation plenoptic imaging are two quantum imaging techniques that ... more Sub-shot-noise imaging and correlation plenoptic imaging are two quantum imaging techniques that enable to overcome different problems of classical imaging systems. Combining the two techniques is not trivial, since the former is based on the detection of identical corresponding modes to subtract noise, while the latter requires the detection of different modes to perform directional reconstruction. In this paper, we experimentally show the possibility to obtain a noise-reduction factor smaller than one, a necessary condition to perform sub-shot-noise imaging, in a setup that can be adapted to correlation plenoptic imaging.
Applied Sciences, 2018
Plenoptic imaging (PI) enables refocusing, depth-of-field (DOF) extension and 3D visualization, t... more Plenoptic imaging (PI) enables refocusing, depth-of-field (DOF) extension and 3D visualization, thanks to its ability to reconstruct the path of light rays from the lens to the image. However, in state-of-the-art plenoptic devices, these advantages come at the expenses of the image resolution, which is always well above the diffraction limit defined by the lens numerical aperture (NA). To overcome this limitation, we have proposed exploiting the spatio-temporal correlations of light, and to modify the ghost imaging scheme by endowing it with plenoptic properties. This approach, named Correlation Plenoptic Imaging (CPI), enables pushing both resolution and DOF to the fundamental limit imposed by wave-optics. In this paper, we review the methods to perform CPI both with chaotic light and with entangled photon pairs. Both simulations and a proof-of-principle experimental demonstration of CPI will be presented.
Physical review letters, Jan 15, 2017
Traditional optical imaging faces an unavoidable trade-off between resolution and depth of field ... more Traditional optical imaging faces an unavoidable trade-off between resolution and depth of field (DOF). To increase resolution, high numerical apertures (NAs) are needed, but the associated large angular uncertainty results in a limited range of depths that can be put in sharp focus. Plenoptic imaging was introduced a few years ago to remedy this trade-off. To this aim, plenoptic imaging reconstructs the path of light rays from the lens to the sensor. However, the improvement offered by standard plenoptic imaging is practical and not fundamental: The increased DOF leads to a proportional reduction of the resolution well above the diffraction limit imposed by the lens NA. In this Letter, we demonstrate that correlation measurements enable pushing plenoptic imaging to its fundamental limits of both resolution and DOF. Namely, we demonstrate maintaining the imaging resolution at the diffraction limit while increasing the depth of field by a factor of 7. Our results represent the theore...
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Papers by Francesco Di Lena