Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2309.09325

Theoretical framework for real time sub-micron depth monitoring using quantum inline coherent imaging

Alexander A. C. Wainwright, Khaled Madhoun

Published Sep 17, 2023• 0 citations
arXivHTMLPDF

Abstract

Inline Coherent Imaging (ICI) is a reliable method for real-time monitoring of various laser processes, including keyhole welding, additive manufacturing, and micromachining. However, the axial resolution is limited to greater than 2 μm making ICI unsuitable for monitoring submicron processes. Advancements in Quantum Optical Coherence Tomography (QOCT), which uses a Hong-Ou-Mandel (HOM) interferometer, has the potential to address this issue by achieving better than 1 μm depth resolution. While time-resolved QOCT is slow, Fourier domain QOCT (FD-QOCT) overcomes this limitation, enabling submicron scale real-time process monitoring. Here we review the fundamentals of FD-QOCT and QOCT and propose a Quantum Inline Coherent Imaging system based on FD-QOCT. Using frequency entangled sources available today the system has a theoretical resolution of 0.17 microns, making it suitable for submicron real-time process monitoring.

DOI
10.48550/arxiv.2309.09325

Related papers

Quantum-locked tomography for turbulence immune 3D imaging at the micron scale

Kexin Yang, Ruimin Huang, Yudie Li +7 more

Random phase perturbations in dynamic media fundamentally limit a broad class of conventional optical imaging, causing severe motion artifacts and resolution degradation in applications from in vivo biomedical tomography to remote sensing. Here, we demonstrate that quantum optical coherence tomography (QOCT), leveraging Hong–Ou–Mandel interference of entangled photons, achieves unprecedented resilience against these disturbances and provides quantitative formulas characterizing this robustness. Theoretically, QOCT exhibits >10-fold slower visibility decay than classical optical coherence tomography (OCT) under random phase fluctuations. Experimentally, it maintains >90 % baseline visibility through turbulent media—conditions where OCT fails. Crucially, this robustness stems from intrinsic quantum properties: interference detection between indistinguishable paths of frequency-entangled identical photons eliminates random path length perturbations and provides native axial resolution doubling (versus classical OCT at identical bandwidth), with neither post-processing nor system modifications required. We validate QOCT’s capability by performing micron-scale 3D tomography of structured targets through dynamic turbid liquids, achieving high-fidelity reconstructions under strong flow turbulence (Reynolds number >5600). This work establishes a paradigm for quantum-enhanced imaging, enabling high-precision volumetric tomography in scenarios from motion artifact-free biological diagnosis to non-contact subaquatic mapping through turbulent air–water interfaces.

Photonics Research•Mar 2, 2026•0 citations

Fourier domain quantum optical coherence tomography

Sylwia M. Kolenderska, Frédérique Vanholsbeeck, Piotr Leszek Kolenderski

Quantum optical coherence tomography (Q-OCT) is the non-classical counterpart of optical coherence tomography (OCT), a high-resolution 3D imaging technique based on white-light interferometry. Because Q-OCT uses a source of frequency-entangled photon pairs, not only is the axial resolution not affected by dispersion mismatch in the interferometer but is also inherently improved by a factor of two. Unfortunately, practical applications of Q-OCT are hindered by image-scrambling artefacts and slow acquisition times. Here, we present a theoretical analysis of a novel approach that is free of these problems: Fourier domain Q-OCT (Fd-Q-OCT). Based on a photon pair coincidence detection as in the standard Q-OCT configuration, it also discerns each photon pair by their wavelength. We show that all the information about the internal structures of the object is encoded in the joint spectrum and can be easily retrieved through Fourier transformation. No depth scanning is required, making our technique potentially faster than standard Q-OCT. Finally, we show that the data available in the joint spectrum enables artefact removal and discuss prospective algorithms for doing so.

Optics Express•Aug 6, 2020•29 citations

High-volume-resolution quantum optical coherence tomography imaging with efficient artifact removal

Naofumi Abe, Tomoyasu Horino, Yoko Kawaguchi +2 more

Optical coherence tomography (OCT) has been widely used in many applications owing to its non-invasive nature. However, its axial resolution can be degraded due to dispersion in samples and optical systems. Quantum optical coherence tomography (QOCT) can overcome this problem and has thus attracted attention. However, QOCT exhibits two challenges: insufficient volume resolution and artifacts in images. Here, we realize high-volume-resolution QOCT imaging with efficient artifact removal. We evaluate our QOCT system to have an axial resolution of 1.5 μm and a lateral resolution of 1.6 μm, giving a volume resolution of 4.0 μm 3 (4.0 fL). We show that high-volume-resolution QOCT imaging is achievable even under group velocity dispersion. We also show that artifacts appearing inherently in the QOCT images can be removed by fast post-processing using the maximum clique search in graph theory. We believe that this study paves the way for QOCT imaging of three-dimensional fine structures.

Optics Express•Jun 11, 2026•0 citations

Experimental demonstration of full-field quantum optical coherence tomography

Zeferino Ibarra-Borja, Carlos Sevilla-Gutiérrez, Roberto Ramírez-Alarcón +2 more

We present, to the best of our knowledge, the first implementation of full-field quantum optical coherence tomography (FF-QOCT). In our system, we are able to obtain full three-dimensional (3D) information about the internal structure of a sample under study by relying on transversely resolved Hong–Ou–Mandel (HOM) interferometry with the help of an intensified CCD (ICCD) camera. Our system requires a single axial scan, obtaining full-field transverse single-photon intensity in coincidence with the detection of the sibling photon for each value of the signal-idler temporal delay. We believe that this capability constitutes a significant step forward toward the implementation of QOCT as a practical biomedical imaging technique.

Photonics Research•Dec 19, 2019•36 citations

Quantum optical coherence tomography using three time-energy entangled photons

Dorilian Lopez-Mago, Arturo Burguete Lopez, Eernesto Campos

Quantum Optical Coherence Tomography can achieve a greater image resolution compared to its classical counterpart, due to the entanglement of the photon pairs. Following the idea that higher the number of entangled photons, higher the resolution, we study the physical underpinnings that appear when using photon triplets. Unlike the usual Hong-Ou-Mandel interferometer used for QOCT, a much simpler implementation in the form of a Michelson interferometer is used in this work. We find that axial resolution can be improved by a factor of four. Additionally, we provide the numerical method to reconstruct the image given the triple coincidence rate.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Sep 13, 2016•0 citations

Quantum Optical Coherence Microscopy for Bioimaging Applications

Pablo Yepiz-Graciano, Zeferino Ibarra-Borja, Roberto Ramírez-Alarcón +4 more

Quantum-optical coherence tomography (QOCT) is an optical sectioning modality based on the quantum interference of entangled photon pairs in the well-known Hong-Ou-Mandel interferometer. Despite its promise, the technique is far from being competitive with current classical OCT devices due to the long required acquisition times, derived from the low photon-pair emission rates. In this work, we, on the one hand, demonstrate a quantum optical coherence microscopy technique, based on full-field QOCT, which employs entangled collinear photon pairs in a Linnik interferometer designed to overcome some of the limitations of previous QOCT implementations, and, on the other hand, test it on representative samples, including glass layers with manufactured transverse patterns and metal-coated biological specimens. In our setup, while the idler photon is collected with a multimode fiber, the signal photon is detected by an intensified charge-coupled device camera, leading to full-field transverse reconstruction through a single-axial acquisition sequence. Interestingly, our setup permits concurrent OCT and QOCT trace acquisition, the former with greater counts and the latter with the benefit of quantum-conferred advantages. We hope that our current results will represent a significant step forward towards the actual applicability of QOCT, e.g., in clinical settings.

arXiv:2205.01292•Physical Review Applied•Sep 22, 2022•20 citations
Inline Coherent Imaging (ICI) is a reliable method for real-time monitoring of various laser processes, including keyhole welding, additive manufacturing, and micromachining. However, the axial resolution is limited to greater than 2 μm making ICI unsuitable for monitoring submicron processes. Advancements in Quantum Optical Coherence Tomography (QOCT), which uses a Hong-Ou-Mandel (HOM) interferometer, has the potential to address this issue by achieving better than 1 μm depth resolution. While time-resolved QOCT is slow, Fourier domain QOCT (FD-QOCT) overcomes this limitation, enabling submicron scale real-time process monitoring. Here we review the fundamentals of FD-QOCT and QOCT and propose a Quantum Inline Coherent Imaging system based on FD-QOCT. Using frequency entangled sources available today the system has a theoretical resolution of 0.17 microns, making it suitable for submicron real-time process monitoring.
Random phase perturbations in dynamic media fundamentally limit a broad class of conventional optical imaging, causing severe motion artifacts and resolution degradation in applications from in vivo biomedical tomography to remote sensing. Here, we demonstrate that quantum optical coherence tomography (QOCT), leveraging Hong–Ou–Mandel interference of entangled photons, achieves unprecedented resilience against these disturbances and provides quantitative formulas characterizing this robustness. Theoretically, QOCT exhibits >10-fold slower visibility decay than classical optical coherence tomography (OCT) under random phase fluctuations. Experimentally, it maintains >90 % baseline visibility through turbulent media—conditions where OCT fails. Crucially, this robustness stems from intrinsic quantum properties: interference detection between indistinguishable paths of frequency-entangled identical photons eliminates random path length perturbations and provides native axial resolution doubling (versus classical OCT at identical bandwidth), with neither post-processing nor system modifications required. We validate QOCT’s capability by performing micron-scale 3D tomography of structured targets through dynamic turbid liquids, achieving high-fidelity reconstructions under strong flow turbulence (Reynolds number >5600). This work establishes a paradigm for quantum-enhanced imaging, enabling high-precision volumetric tomography in scenarios from motion artifact-free biological diagnosis to non-contact subaquatic mapping through turbulent air–water interfaces.
Quantum optical coherence tomography (Q-OCT) is the non-classical counterpart of optical coherence tomography (OCT), a high-resolution 3D imaging technique based on white-light interferometry. Because Q-OCT uses a source of frequency-entangled photon pairs, not only is the axial resolution not affected by dispersion mismatch in the interferometer but is also inherently improved by a factor of two. Unfortunately, practical applications of Q-OCT are hindered by image-scrambling artefacts and slow acquisition times. Here, we present a theoretical analysis of a novel approach that is free of these problems: Fourier domain Q-OCT (Fd-Q-OCT). Based on a photon pair coincidence detection as in the standard Q-OCT configuration, it also discerns each photon pair by their wavelength. We show that all the information about the internal structures of the object is encoded in the joint spectrum and can be easily retrieved through Fourier transformation. No depth scanning is required, making our technique potentially faster than standard Q-OCT. Finally, we show that the data available in the joint spectrum enables artefact removal and discuss prospective algorithms for doing so.
Optical coherence tomography (OCT) has been widely used in many applications owing to its non-invasive nature. However, its axial resolution can be degraded due to dispersion in samples and optical systems. Quantum optical coherence tomography (QOCT) can overcome this problem and has thus attracted attention. However, QOCT exhibits two challenges: insufficient volume resolution and artifacts in images. Here, we realize high-volume-resolution QOCT imaging with efficient artifact removal. We evaluate our QOCT system to have an axial resolution of 1.5 μm and a lateral resolution of 1.6 μm, giving a volume resolution of 4.0 μm 3 (4.0 fL). We show that high-volume-resolution QOCT imaging is achievable even under group velocity dispersion. We also show that artifacts appearing inherently in the QOCT images can be removed by fast post-processing using the maximum clique search in graph theory. We believe that this study paves the way for QOCT imaging of three-dimensional fine structures.
We present, to the best of our knowledge, the first implementation of full-field quantum optical coherence tomography (FF-QOCT). In our system, we are able to obtain full three-dimensional (3D) information about the internal structure of a sample under study by relying on transversely resolved Hong–Ou–Mandel (HOM) interferometry with the help of an intensified CCD (ICCD) camera. Our system requires a single axial scan, obtaining full-field transverse single-photon intensity in coincidence with the detection of the sibling photon for each value of the signal-idler temporal delay. We believe that this capability constitutes a significant step forward toward the implementation of QOCT as a practical biomedical imaging technique.
Quantum Optical Coherence Tomography can achieve a greater image resolution compared to its classical counterpart, due to the entanglement of the photon pairs. Following the idea that higher the number of entangled photons, higher the resolution, we study the physical underpinnings that appear when using photon triplets. Unlike the usual Hong-Ou-Mandel interferometer used for QOCT, a much simpler implementation in the form of a Michelson interferometer is used in this work. We find that axial resolution can be improved by a factor of four. Additionally, we provide the numerical method to reconstruct the image given the triple coincidence rate.
Quantum-optical coherence tomography (QOCT) is an optical sectioning modality based on the quantum interference of entangled photon pairs in the well-known Hong-Ou-Mandel interferometer. Despite its promise, the technique is far from being competitive with current classical OCT devices due to the long required acquisition times, derived from the low photon-pair emission rates. In this work, we, on the one hand, demonstrate a quantum optical coherence microscopy technique, based on full-field QOCT, which employs entangled collinear photon pairs in a Linnik interferometer designed to overcome some of the limitations of previous QOCT implementations, and, on the other hand, test it on representative samples, including glass layers with manufactured transverse patterns and metal-coated biological specimens. In our setup, while the idler photon is collected with a multimode fiber, the signal photon is detected by an intensified charge-coupled device camera, leading to full-field transverse reconstruction through a single-axial acquisition sequence. Interestingly, our setup permits concurrent OCT and QOCT trace acquisition, the former with greater counts and the latter with the benefit of quantum-conferred advantages. We hope that our current results will represent a significant step forward towards the actual applicability of QOCT, e.g., in clinical settings.