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  1. Article ; Online: Holographic point source for digital lensless holographic microscopy.

    Lopera, Maria J / Trujillo, Carlos

    Optics letters

    2022  Volume 47, Issue 11, Page(s) 2862–2865

    Abstract: A holographic point source (HPS) developed for digital lensless holographic microscopy (HPS-DLHM) is presented. The HPS is an off-axis phase transmission hologram of an experimental micrometer pinhole recorded on a photopolymer holographic film. An ... ...

    Abstract A holographic point source (HPS) developed for digital lensless holographic microscopy (HPS-DLHM) is presented. The HPS is an off-axis phase transmission hologram of an experimental micrometer pinhole recorded on a photopolymer holographic film. An amplitude division interferometer, adjusted to operate at maximum diffraction efficiency, has been employed to record the hologram. The results of HPS-DLHM have been contrasted with the results obtained via conventional DLHM, and the two techniques were found to give similar measurements. Compared with conventional pinhole-based DLHM illumination, our cost-effective proposal provides increased mechanical stability, the possibility of wider spherical illumination cones, and shorter reconstruction distances. These superior features pave the way to applying this quantitative phase imaging (QPI) technique in biomedical and telemedicine applications. The imaging capabilities of our HPS-DLHM proposal have been tested by using an intricate sample of a honeybee leg, a low-absorption sample of epithelial cheek cells, a 1951 USAF test target, and smeared human erythrocytes.
    MeSH term(s) Animals ; Bees ; Erythrocytes ; Holography/methods ; Humans ; Lighting/methods ; Microscopy/methods
    Language English
    Publishing date 2022-06-01
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4794
    ISSN (online) 1539-4794
    DOI 10.1364/OL.459146
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Linear diattenuation imaging of biological samples with digital lensless holographic microscopy.

    Lopera, Maria J / Trujillo, Carlos

    Applied optics

    2022  Volume 61, Issue 5, Page(s) B77–B82

    Abstract: A digital lensless holographic microscope (DLHM) sensitive to the linear diattenuation produced by biological samples is reported. The insertion of a linear polarization-states generator and a linear polarization-states analyzer in a typical DLHM setup ... ...

    Abstract A digital lensless holographic microscope (DLHM) sensitive to the linear diattenuation produced by biological samples is reported. The insertion of a linear polarization-states generator and a linear polarization-states analyzer in a typical DLHM setup allows the proper linear diattenuation imaging of microscopic samples. The proposal has been validated for simulated and experimental biological samples containing calcium oxalate crystals extracted from agave leaves and potato starch grains. The performance of the proposed method is similar to that of a traditional polarimetric microscope to obtain linear diattenuation images of microscopic samples but with the advantages of DLHM, such as numerical refocusing, cost effectiveness, and the possibility of field-portable implementation.
    MeSH term(s) Cost-Benefit Analysis ; Holography/methods ; Microscopy/methods
    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.440376
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. 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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