We present a novel approach to three-dimensional optical microscopy, named correlation light-field microscopy (CLM). This approach is based on correlation plenoptic imaging and exploits correlations between intensity fluctuations, intrinsic in chaotic light, to retrieve both spatial information about the intensity distribution of light on the sample and angular information about the directions of propagation of the light rays. Such a plenoptic (or light-field) information about the sample enables an extension of the natural depth of field, while avoiding the intrinsic loss of spatial resolution occurring in conventional light-field microscopy. We discuss the capability of CLM of refocusing out-of-focus planes of the sample, paving the way to scanning-free three-dimensional reconstruction while keeping the at-focus resolution at the diffraction limit showing a brief comparison with light-field microscopy. Finally we discuss the perspective of improvements in CLM acquisition speed by the integration of SPAD array sensors in the setup.
We will show that photon correlations can be employed to overcome the typical limitations of conventional plenoptic imaging devices, thus leading to quantum-enhanced plenoptic imaging. In particular, we will show an unprecedented combination of resolution and depth of field combined with refocusing capability and depth extension. We will show experimental results obtained in different application scenarios, ranging from microscopy to photography-like protocols. Significant advances in acquisition speed will also be discussed, as achieved by both hardware (e.g., use of SPAD arrays, as opposed to common CMOS and CCD cameras) and software (e.g., compressive sensing, quantum tomography) solutions.
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.
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.
We introduce a new generation of 3D imaging devices based on quantum plenoptic imaging. Position-momentum entanglement and photon number correlations are exploited to provide a scan-free 3D image after post-processing of the collected light intensity signal. We explore the steps toward designing and implementing quantum plenop- tic cameras with dramatically improved performances, unattainable in standard plenoptic cameras, such as diffraction-limited resolution, large depth of focus, and ultra-low noise. However, to make these new types of devices attractive to end-users, two main challenges need to be tackled: the reduction of the acquisition times, that for the commercially available high-resolution cameras would be from tens of seconds to a few minutes, and a speed-up in processing the large amount of data that are acquired, in order to retrieve 3D reconstructions or refocused 2D images. To address these challenges, we are employing high-resolution SPAD (single photon avalanche diode) arrays and high-performance low-level programming of ultra-fast electronics, combined with compressive sensing and quantum tomography algorithms, with the aim of reducing both the acquisition and the elaboration time by one or possibly two orders of magnitude. Moreover, in order to achieve the quantum limit and further increase the volumetric resolution beyond the Rayleigh diffraction limit, we explored dedicated pro- tocols based on quantum Fisher information. Finally, we discuss how this new generation of quantum plenoptic devices could be exploited in different fields of research, such as 3D microscopy and space imaging.
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.
We review the signal-to-noise properties of two setups for Correlation Plenoptic Imaging (CPI), a novel technique that exploits the correlations of light intensity to perform the typical tasks of plenoptic imaging: refocusing out-of- focus parts of the scene, extending the depth of field, reconstruct 3D objects, As opposed to first-order plenoptic imaging, based on direct intensity measurement, CPI does not entail a loss of spatial resolution. Both setups are based on the properties of chaotic light and employ the concept of ghost imaging in different ways: the first one to image the object, the second one to image the focusing element. We show that the SNR can be easier to control in the second CPI scheme, in which the object is focused by a lens.
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