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  1. Article ; Online: Noise reduction in digital holography phase maps by phase-preserving discrete Fourier resampling.

    Buitrago-Duque, Carlos / Garcia-Sucerquia, Jorge

    Optics letters

    2023  Volume 48, Issue 21, Page(s) 5807–5810

    Abstract: Several methods have been proposed to reduce the detrimental effects of coherent noise in holographic imaging. Among them, the use of spatial-frequency masking or resampling has been widely applied because of its low implementation complexity and well- ... ...

    Abstract Several methods have been proposed to reduce the detrimental effects of coherent noise in holographic imaging. Among them, the use of spatial-frequency masking or resampling has been widely applied because of its low implementation complexity and well-studied trade-off between denoising effectiveness and spatial resolution. While the digital application of this method has been successfully demonstrated for intensity images, its application to phase maps fails. This work shows that the phase applicability of these methods depends on the use of resampling masks that strictly keep the zero-order spatial frequencies. Alternative masks are proposed that demonstrate effective single-shot noise reduction in experimental phase maps from digital holographic microscopy. The resulting method is potentially extendable to any other complex-valued-field retrieval technique.
    Language English
    Publishing date 2023-10-31
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4794
    ISSN (online) 1539-4794
    DOI 10.1364/OL.504038
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Robust and compact digital Lensless Holographic microscope for Label-Free blood smear imaging.

    Buitrago-Duque, Carlos / Patiño-Jurado, Brayan / Garcia-Sucerquia, Jorge

    HardwareX

    2023  Volume 13, Page(s) e00408

    Abstract: The lack of equipped healthcare infrastructure in isolated hard-to-reach zones exposes their population to a higher risk of complications in common diseases. With a timely diagnosis setting a life-altering difference, worldwide efforts have been ... ...

    Abstract The lack of equipped healthcare infrastructure in isolated hard-to-reach zones exposes their population to a higher risk of complications in common diseases. With a timely diagnosis setting a life-altering difference, worldwide efforts have been conducted for the development of point-of-care testing (PoCT) with cost-effective devices. Among the most common interests in PoCT is the analysis of blood smear samples, as they can help to detect, diagnose, and monitor a wide range of diseases and disorders. With microscopy being the traditional tool for these analyses, a significative advance has been the development of cost-effective digital holographic microscopy systems, driven in part by its label-free imaging capabilities that waive the need for any sample preprocessing. Here, a robust and portable digital lensless holographic microscope, functionalized for the analysis of non-preprocessed blood smear samples in PoCT environments, is presented, and its viability is tested in the observation of red blood cells. The device uses an optical fiber with a cone-shaped tip instead of a pinhole, which ensures the sturdiness of the system and eliminates the need for challenging alignment. While the distances of the microscope can be tuned before fabrication, the herein-reported operational parameters are functionalized for the specific analysis of blood samples.
    Language English
    Publishing date 2023-02-25
    Publishing country England
    Document type Journal Article
    ISSN 2468-0672
    ISSN (online) 2468-0672
    DOI 10.1016/j.ohx.2023.e00408
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Realistic simulation and real-time reconstruction of digital holographic microscopy experiments in ImageJ.

    Buitrago-Duque, Carlos / Garcia-Sucerquia, Jorge

    Applied optics

    2022  Volume 61, Issue 5, Page(s) B56–B63

    Abstract: The description, implementation, and validation of an ImageJ plugin that allows the realistic simulation and real-time reconstruction of digital holographic microscopy (DHM) experiments are presented. The simulation module implements a telecentric image- ... ...

    Abstract The description, implementation, and validation of an ImageJ plugin that allows the realistic simulation and real-time reconstruction of digital holographic microscopy (DHM) experiments are presented. The simulation module implements a telecentric image-plane DHM recording scheme with fully configurable imaging system, interference, and scaling parameters, including the possibility of defining an estimate of the roughness distribution of the sample to produce realistic coherent-noise affectations. The reconstruction module allows the computation of amplitude, intensity, or phase, from digital holograms' input as either single images or video streams for real-time processing; this module also implements user-defined fine-tuning parameters, allowing subpixel linear phase compensations and digital refocusing of the complex-valued reconstructed fields. In this note, the functionality of the plugin is illustrated by simulating the noisy DHM recording of a phase-only resolution test target and the reconstruction of both the resulting synthetic hologram and an equivalent experimental recording; the results show good agreement between the simulation and the experimental recording, and accurate measurements on the reconstructed information, thus granting the use of either module with full confidence according to needs and possibilities.
    Language English
    Publishing date 2022-02-21
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4522
    ISSN (online) 1539-4522
    DOI 10.1364/AO.443137
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Physical pupil manipulation for speckle reduction in digital holographic microscopy.

    Buitrago-Duque, Carlos / Garcia-Sucerquia, Jorge

    Heliyon

    2021  Volume 7, Issue 1, Page(s) e06098

    Abstract: The reduction of speckle noise by physically changing the pupil of the imaging system, as first envisioned in optical holography, is experimentally applied to a digital holographic microscope (DHM). The imaging pupil of a DHM, operating in image plane ... ...

    Abstract The reduction of speckle noise by physically changing the pupil of the imaging system, as first envisioned in optical holography, is experimentally applied to a digital holographic microscope (DHM). The imaging pupil of a DHM, operating in image plane telecentric-afocal architecture, is changed in a controlled way between successive recordings, allowing the shooting of multiple partially-decorrelated holograms. Averaging the numerically reconstructed holograms yields amplitude and/or phase images with reduced speckle noise. Experimental results of biological specimens and a phase-only resolution test show the feasibility to recover micron-sized features in images with reduced speckle noise.
    Language English
    Publishing date 2021-01-30
    Publishing country England
    Document type Journal Article
    ZDB-ID 2835763-2
    ISSN 2405-8440
    ISSN 2405-8440
    DOI 10.1016/j.heliyon.2021.e06098
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Adapting a Blu-ray optical pickup unit as a point source for digital lensless holographic microscopy.

    Tobón-Maya, Heberley / Gómez-Ramírez, Alejandra / Buitrago-Duque, Carlos / Garcia-Sucerquia, Jorge

    Applied optics

    2023  Volume 62, Issue 10, Page(s) D39–D47

    Abstract: The adaptation of an off-the-shelf Blu-ray optical pickup unit (OPU) into a highly versatile point source for digital lensless holographic microscopy (DLHM) is presented. DLHM performance is mostly determined by the optical properties of the point source ...

    Abstract The adaptation of an off-the-shelf Blu-ray optical pickup unit (OPU) into a highly versatile point source for digital lensless holographic microscopy (DLHM) is presented. DLHM performance is mostly determined by the optical properties of the point source of spherical waves used for free-space magnification of the sample's diffraction pattern; in particular, its wavelength and numerical aperture define the achievable resolution, and its distance to the recording medium sets the magnification. Through a set of straightforward modifications, a commercial Blu-ray OPU can be transformed into a DLHM point source with three selectable wavelengths, a numerical aperture of up to 0.85, and integrated micro-displacements in both axial and transversal directions. The functionality of the OPU-based point source is then experimentally validated in the observation of micrometer-sized calibrated samples and biological specimens of common interest, showing the feasibility of obtaining sub-micrometer resolution and offering a versatile option for the development of new cost-effective and portable microscopy devices.
    Language English
    Publishing date 2023-05-01
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4522
    ISSN (online) 1539-4522
    DOI 10.1364/AO.474916
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Open-access database for digital lensless holographic microscopy and its application on the improvement of deep-learning-based autofocusing models.

    Buitrago-Duque, Carlos / Tobón-Maya, Heberley / Gómez-Ramírez, Alejandra / Zapata-Valencia, Samuel I / Lopera, Maria J / Trujillo, Carlos / Garcia-Sucerquia, Jorge

    Applied optics

    2024  Volume 63, Issue 7, Page(s) B49–B58

    Abstract: Among modern optical microscopy techniques, digital lensless holographic microscopy (DLHM) is one of the simplest label-free coherent imaging approaches. However, the hardware simplicity provided by the lensless configuration is often offset by the ... ...

    Abstract Among modern optical microscopy techniques, digital lensless holographic microscopy (DLHM) is one of the simplest label-free coherent imaging approaches. However, the hardware simplicity provided by the lensless configuration is often offset by the demanding computational postprocessing required to match the retrieved sample information to the user's expectations. A promising avenue to simplify this stage is the integration of artificial intelligence and machine learning (ML) solutions into the DLHM workflow. The biggest challenge to do so is the preparation of an extensive and high-quality experimental dataset of curated DLHM recordings to train ML models. In this work, a diverse, open-access dataset of DLHM recordings is presented as support for future research, contributing to the data needs of the applied research community. The database comprises 11,760 experimental DLHM holograms of bio and non-bio samples with diversity on the main recording parameters of the DLHM architecture. The database is divided into two datasets of 10 independent imaged samples. The first group, named multi-wavelength dataset, includes 8160 holograms and was recorded using laser diodes emitting at 654 nm, 510 nm, and 405 nm; the second group, named single-wavelength dataset, is composed of 3600 recordings and was acquired using a 633 nm He-Ne laser. All the experimental parameters related to the dataset acquisition, preparation, and calibration are described in this paper. The advantages of this large dataset are validated by re-training an existing autofocusing model for DLHM and as the training set for a simpler architecture that achieves comparable performance, proving its feasibility for improving existing ML-based models and the development of new ones.
    Language English
    Publishing date 2024-03-04
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4522
    ISSN (online) 1539-4522
    DOI 10.1364/AO.507412
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Non-approximated Rayleigh-Sommerfeld diffraction integral: advantages and disadvantages in the propagation of complex wave fields.

    Buitrago-Duque, Carlos / Garcia-Sucerquia, Jorge

    Applied optics

    2019  Volume 58, Issue 34, Page(s) G11–G18

    Abstract: Advantages and disadvantages of the non-approximated numerical implementation of the Rayleigh-Sommerfeld diffraction integral (RSD) are revisited. In this work, it is shown that as trade-off for its large computation load, the non-approximated RSD ... ...

    Abstract Advantages and disadvantages of the non-approximated numerical implementation of the Rayleigh-Sommerfeld diffraction integral (RSD) are revisited. In this work, it is shown that as trade-off for its large computation load, the non-approximated RSD removes any limitation on the propagation range and does not introduce any artifact in the computed wave field. A non-approximated GPU implementation of the RSD is contrasted with the angular spectrum, the Fresnel transform, and a fast Fourier transform implementation of the RSD. The forecasted phase shift introduced in the propagated wave fields as light is diffracted on complementary apertures and utilized as a metric to quantify the performance of the tested methods. An application to numerical reconstructions with arbitrary shape and size of digital recorded holograms from digital lensless holographic microscopy is presented.
    Language English
    Publishing date 2019-12-23
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4522
    ISSN (online) 1539-4522
    DOI 10.1364/AO.58.000G11
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Fast-iterative blind phase-shifting digital holographic microscopy using two images.

    Castañeda, Raul / Buitrago-Duque, Carlos / Garcia-Sucerquia, Jorge / Doblas, Ana

    Applied optics

    2020  Volume 59, Issue 24, Page(s) 7469–7476

    Abstract: Digital holographic microscopy (DHM) has consolidated as a tool for diagnosis and measuring in life sciences, thanks to its capability to perform quantitative phase imaging. The reduction of the acquisition and computation time has driven the development ...

    Abstract Digital holographic microscopy (DHM) has consolidated as a tool for diagnosis and measuring in life sciences, thanks to its capability to perform quantitative phase imaging. The reduction of the acquisition and computation time has driven the development of diverse reconstruction methodologies using a single-shot and two-frame approach. Methods based on the Fourier transform, the Hilbert transform, and the phase derivative are counted among the most utilized. The sensitivity of those methods is highly dependent on the compensation of the phase step, which requires the accurate knowledge of the phase shift between the two recorded holograms. Here, an alternative fast-iterative method based on the demodulation of the different components of the recorded interferograms is presented. The novelties of the proposed two-frame approach are: minimum number of images, since it requires 2 recorded holograms; a minimum phase error of the order of 0.005% independently of the phase step ranging from 0 to 180 deg.; a maximum correlation coefficient equal to 1 between the phase and the retrieved phase image; and, finally, a reduced processing time compared with the previous three-frame approach. Experimental results demonstrate the goodness and feasibility of the proposed technique.
    MeSH term(s) Algorithms ; Computer Simulation ; Equipment Design ; Erythrocytes ; Fourier Analysis ; Holography/methods ; Humans ; Image Processing, Computer-Assisted ; Microscopy/instrumentation ; Microscopy/methods
    Language English
    Publishing date 2020-09-08
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4522
    ISSN (online) 1539-4522
    DOI 10.1364/AO.398352
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Phase-shifting digital holographic microscopy with an iterative blind reconstruction algorithm.

    Doblas, Ana / Buitrago-Duque, Carlos / Robinson, Aaron / Garcia-Sucerquia, Jorge

    Applied optics

    2019  Volume 58, Issue 34, Page(s) G311–G317

    Abstract: In phase-shifting digital holographic microscopy (PS-DHM), the reconstructed phase map is obtained after processing several holograms of the same scene with a phase shift between them. Most of the reconstruction algorithms in PS-DHM require an accurate ... ...

    Abstract In phase-shifting digital holographic microscopy (PS-DHM), the reconstructed phase map is obtained after processing several holograms of the same scene with a phase shift between them. Most of the reconstruction algorithms in PS-DHM require an accurate and known phase shift between the recorded holograms. This requirement limits the applicability of the method. To ease the use of PS-DHM, this paper presents an iterative-blind phase shift extraction method based on demodulation of the different components of the recorded holograms. The method uses a DHM system operating in a slightly off-axis architecture. The proposed method uses three-frame holograms with arbitrary and unequal phase shifts between them and therefore eases the use of the PS-DHM. We believe both simulated and experimental results demonstrate the goodness and feasibility of the proposed technique.
    Language English
    Publishing date 2019-12-23
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4522
    ISSN (online) 1539-4522
    DOI 10.1364/AO.58.00G311
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Open-source, cost-effective, portable, 3D-printed digital lensless holographic microscope.

    Tobon-Maya, Heberley / Zapata-Valencia, Samuel / Zora-Guzmán, Erick / Buitrago-Duque, Carlos / Garcia-Sucerquia, Jorge

    Applied optics

    2021  Volume 60, Issue 4, Page(s) A205–A214

    Abstract: In this work, the design, construction, and testing of the most cost-effective digital lensless holographic microscope to date are presented. The architecture of digital lensless holographic microscopy (DLHM) is built by means of a 3D-printed setup and ... ...

    Abstract In this work, the design, construction, and testing of the most cost-effective digital lensless holographic microscope to date are presented. The architecture of digital lensless holographic microscopy (DLHM) is built by means of a 3D-printed setup and utilizing off-the-shelf materials to produce a DLHM microscope costing
    MeSH term(s) Animals ; Cheek/diagnostic imaging ; Cost-Benefit Analysis ; Drosophila melanogaster/metabolism ; Erythrocytes/metabolism ; Head/diagnostic imaging ; Holography/instrumentation ; Holography/methods ; Microscopy/instrumentation ; Microscopy/methods ; Printing, Three-Dimensional
    Language English
    Publishing date 2021-03-08
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4522
    ISSN (online) 1539-4522
    DOI 10.1364/AO.405605
    Database MEDical Literature Analysis and Retrieval System OnLINE

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