English
norskBlar i forfatter "Mehta, Dalip Singh"
Viser treff 1-18 av 18
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Characterization of color cross-talk of CCD detectors and its influence in multispectral quantitative phase imaging
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-08)Multi-spectral quantitative phase imaging (QPI) is an emerging imaging modality for wavelength dependent studies of several biological and industrial specimens. Simultaneous multi-spectral QPI is generally performed with color CCD cameras. Here, we present a new approach for accurately measuring the color crosstalk of 2D area detectors, without needing prior information about camera specifications. ... -
Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-13)Optical coherence tomography (OCT) is being increasingly adopted as a label-free and non-invasive technique for biomedical applications such as cancer and ocular disease diagnosis. Diagnostic information for these tissues is manifest in textural and geometric features of the OCT images, which are used by human expertise to interpret and triage. However, it suffers delays due to the long process of ... -
Effect on the longitudinal coherence properties of a pseudothermal light source as a function of source size and temporal coherence
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-01)In the present Letter, a synthesized pseudothermal light source having high temporal coherence (TC) and low spatial coherence (SC) properties is used. The longitudinal coherence (LC) properties of the spatially extended monochromatic light source are systematically studied. The pseudothermal light source is generated from two different monochromatic laser sources: He–Ne (at 632 nm) and DPSS (at 532 ... -
High space-bandwidth in quantitative phase imaging using partially spatially coherent digital holographic microscopy and a deep neural network
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-16)Quantitative phase microscopy (QPM) is a label-free technique that enables monitoring of morphological changes at the subcellular level. The performance of the QPM system in terms of spatial sensitivity and resolution depends on the coherence properties of the light source and the numerical aperture (NA) of objective lenses. Here, we propose high space-bandwidth quantitative phase imaging using ... -
High spatially sensitive quantitative phase imaging assisted with deep neural network for classification of human spermatozoa under stressed condition
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-04)Sperm cell motility and morphology observed under the bright field microscopy are the only criteria for selecting a particular sperm cell during Intracytoplasmic Sperm Injection (ICSI) procedure of Assisted Reproductive Technology (ART). Several factors such as oxidative stress, cryopreservation, heat, smoking and alcohol consumption, are negatively associated with the quality of sperm cell and ... -
High-throughput spatial sensitive quantitative phase microscopy using low spatial and high temporal coherent illumination
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-04)High space-bandwidth product with high spatial phase sensitivity is indispensable for a single-shot quantitative phase microscopy (QPM) system. It opens avenue for widespread applications of QPM in the field of biomedical imaging. Temporally low coherence light sources are implemented to achieve high spatial phase sensitivity in QPM at the cost of either reduced temporal resolution or smaller field ... -
Highly temporal stable, wavelength-independent, and scalable field-of-view common-path quantitative phase microscope
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-11)<p><i>Significance:</i> High temporal stability, wavelength independency, and scalable field of view (FOV) are the primary requirements of a quantitative phase microscopy (QPM) system. The high temporal stability of the system provides accurate measurement of minute membrane fluctuations of the biological cells that can be an indicator of disease diagnosis. <p><i>Aim:</i> The main aim of this work ... -
Inflammatory response of macrophages and trophoblasts investigated using structured illumination microscopy and quantitative phase microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09)<i>Introduction</i>: The super-resolution capability of structured illumination microscopy (SIM) (100 nm) enables 3D imaging of mitochondria, and label-free quantitative phase microscopy (QPM) provides nanoscale quantitative phase values relating to cellular thickness and the refractive index of cellular content. -
Label-free non-invasive classification of rice seeds using optical coherence tomography assisted with deep neural network
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-01)Identification of the seed varieties is essential in the quality control and high yield crop growth. The existing methods of varietal identification rely primarily on visual examination and DNA fingerprinting. Although the pattern of DNA fingerprinting allows precise classification of seed varieties but fraught with challenges such as low rate of polymorphism amongst closely related species, destructive ... -
Multi-modal chip-based fluorescence and quantitative phase microscopy for studying inflammation in macrophages
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-24)Total internal reflection fluorescence (TIRF) microscopy benefits from high-sensitivity, low background noise, low photo-toxicity and high-contrast imaging of sub-cellular structures close to the membrane surface. Although, TIRF microscopy provides high-contrast imaging it does not provide quantitative information about morphological features of the biological cells. Here, we propose an integrated ... -
Multimodal on-chip nanoscopy and quantitative phase imaging reveals the nanoscale morphology of liver sinusoidal endothelial cells
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-23)Visualization of three-dimensional (3D) morphological changes in the subcellular structures of a biological specimen is a major challenge in life science. Here, we present an integrated chip-based optical nanoscopy combined with quantitative phase microscopy (QPM) to obtain 3D morphology of liver sinusoidal endothelial cells (LSEC). LSEC have unique morphology with small nanopores (50-300 nm in ... -
Partially spatially coherent digital holographic microscopy and machine learning for quantitative analysis of human spermatozoa under oxidative stress condition
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-05)Semen quality assessed by sperm count and sperm cell characteristics such as morphology and motility, is considered to be the main determinant of men’s reproductive health. Therefore, sperm cell selection is vital in assisted reproductive technology (ART) used for the treatment of infertility. Conventional bright field optical microscopy is widely utilized for the imaging and selection of sperm cells ... -
Quantitative phase microscopy of red blood cells during planar trapping and propulsion
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-08-22)Red blood cells (RBCs) have the ability to undergo morphological deformations during microcirculation, such as changes in surface area, volume and sphericity. Optical waveguide trapping is suitable for trapping, propelling and deforming large cell populations along the length of the waveguide. Bright field microscopy employed with waveguide trapping does not provide quantitative information about ... -
Relationship between the source size at the diffuser plane and the longitudinal spatial coherence function of the optical coherence microscopy system
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-25)Coherence properties of light sources are indispensable for optical coherence microscopy/tomography as they greatly influence the signal-to-noise ratio, axial resolution, and penetration depth of the system. In the present paper, we report the investigation of longitudinal spatial coherence properties of a pseudothermal light source (PTS) as a function of the laser spot size at the rotating diffuser ... -
Sampling moiré method: a tool for sensing quadratic phase distortion and its correction for accurate quantitative phase microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-24)The advantages of quantitative phase microscopy (QPM) such as label-free imaging with high spatial sensitivity, live cell compatibility and high-speed imaging makes it viable for various biological applications. The measurement accuracy of QPM strongly relies on the shape of the recorded interferograms, whether straight or curved fringes are recorded during the data acquisition. Moreover, for a ... -
Single-shot multispectral quantitative phase imaging of biological samples using deep learning
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-16)Multispectral quantitative phase imaging (MS-QPI) is a high-contrast label-free technique for morphological imaging of the specimens. The aim of the present study is to extract spectral dependent quantitative information in single-shot using a highly spatially sensitive digital holographic microscope assisted by a deep neural network. There are three different wavelengths used in our method: 𝜆=532 , ... -
Sub-nanometer height sensitivity by phase shifting interference microscopy under environmental fluctuations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-18)Phase shifting interferometric (PSI) techniques are among the most sensitive phase measurement methods. Owing to its high sensitivity, any minute phase change caused due to environmental instability results into, inaccurate phase measurement. Consequently, a well calibrated piezo electric transducer (PZT) and highly-stable environment is mandatory for measuring accurate phase map using PSI implementation. ... -
Synthetic wavelength scanning interferometry for 3D surface profilometry with extended range of height measurement using multi-colour LED light sources
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-05)We report three-dimensional surface profilometry with extended range of height measurements using synthetic wavelength scanning interferometry without tunable filters, wavelength-tuning lasers, grating elements. We have used inexpensive multiple colour light emitting diodes (LEDs) and operate them sequentially one by one or combination of two or more colours simultaneously to visualize synthetic ...
