1. Articles from Dalip Singh Mehta

    1-19 of 19
    1. Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples

      Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples

      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 the conventional diagnostic procedure and shortage of human expertise. Here, a custom deep learning architecture, LightOCT, is proposed for the classification of OCT images into diagnostically relevant classes. LightOCT is a convolutional neural network with only two convolutional layers and ...

      Read Full Article
    2. High space-bandwidth in quantitative phase imaging using partially spatially coherent optical coherence microscopy and deep neural network

      High space-bandwidth in quantitative phase imaging using partially spatially coherent optical coherence microscopy and deep neural network

      Quantitative phase microscopy (QPM) is a label-free technique that enables to monitor morphological changes at 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 QPM using partially spatially coherent optical coherence microscopy (PSC-OCM) assisted with deep neural network. The PSC source synthesized to improve the spatial sensitivity of the reconstructed phase map from the interferometric images. Further, compatible generative adversarial network (GAN) is used and trained with paired low-resolution (LR) and high-resolution ...

      Read Full Article
    3. Influence of laser spot size at diffuser plane on the longitudinal spatial coherence function of optical coherence microscopy system

      Influence of laser spot size at diffuser plane on the longitudinal spatial coherence function of optical coherence microscopy system

      Coherence properties and wavelength of light sources are indispensable for optical coherence microscopy/tomography (OCM/T) as they greatly influence the signal to noise ratio, axial resolution, and penetration depth of the system. In the present letter, we investigated the longitudinal spatial coherence properties of pseudo/thermal light source (PTS) as a function of spot size at the diffuser plane, which is controlled by translating microscope objective lens towards or away from the diffuser plane. The axial resolution of PTS is found to be maximum ~ 13 µm for the beam spot size of 3.5 mm at the diffuser plane ...

      Read Full Article
    4. Ensemble classifier for improve diagnosis of the breast cancer using optical coherence tomography and machine learning

      Ensemble classifier for improve diagnosis of the breast cancer using optical coherence tomography and machine learning

      The second most leading cause of death in women is breast cancer even after surgery 20%–30% patients require re-surgery for the removal of the incomplete malignant tissue. To reduce the risk of recurrence exact navigation during surgery is essential. In this paper, a multi-level ensemble model is developed to classify the normal and cancerous breast tissue using features extracted from optical coherence tomography images. Both A-line and B-scan features were extracted and the training data feature space was best-first search to select the best feature subset for each base classifier. To improve the performance of the model reverse active ...

      Read Full Article
    5. Volumetric analysis of breast cancer tissues using machine learning and swept-source optical coherence tomography

      Volumetric analysis of breast cancer tissues using machine learning and swept-source optical coherence tomography

      In breast cancer, 20%–30% of cases require a second surgery because of incomplete excision of malignant tissues. Therefore, to avoid the risk of recurrence, accurate detection of the cancer margin by the clinician or surgeons needs some assistance. In this paper, an automated volumetric analysis of normal and breast cancer tissue is done by a machine learning algorithm to separate them into two classes. The proposed method is based on a support-vector-machine-based classifier by dissociating 10 features extracted from the A-line, texture, and phase map by the swept-source optical coherence tomographic intensity and phase images. A set of 88 ...

      Read Full Article
    6. Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples

      Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples

      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 long process of conventional diagnostic procedure and shortage of human expertise. Here, a custom deep learning architecture, LightOCT, is proposed for classification of OCT images into diagnostically relevant classes. LightOCT is a convolutional neural network with only 2 convolutional layers and a fully connected ...

      Read Full Article
    7. In vivo classification of human skin burns using machine learning and quantitative features captured by optical coherence tomography

      In vivo classification of human skin burns using machine learning and quantitative features captured by optical coherence tomography

      We report the first fully automated detection of human skin burn injuries in vivo , with the goal of automatic surgical margin assessment based on optical coherence tomography (OCT) images. Our proposed automated procedure entails building a machine-learning-based classifier by extracting quantitative features from normal and burn tissue images recorded by OCT. In this study, 56 samples (28 normal, 28 burned) were imaged by OCT and eight features were extracted. A linear model classifier was trained using 34 samples and 22 samples were used to test the model. Sensitivity of 91.6% and specificity of 90% were obtained. Our results demonstrate ...

      Read Full Article
    8. Reflection, phase and en -face sectional imaging of scattering objects using quasi-single-shot wide-field optical coherence tomography

      Reflection, phase and en -face sectional imaging of scattering objects using quasi-single-shot wide-field optical coherence tomography

      We report a quasi-single-shot wide-field optical coherence tomography system that enables to measure the reflection, phase and en - face OCT images from the same setup using the glass jig. The jig consisting of a wedge glass substrate and a glue dot is contacted to the tissue surfaces, and the data within glue dot is used to reduce the phase noise of the interference signal. The reconstructed image size of the object was 4.0 mm × 4.3 mm. The standard deviation (STD) of the phase variation was minimized by 54 % and obtained to be 0.027 rad for the poke ...

      Read Full Article
    9. Improvement of the dynamic range using background subtraction in single shot wide-field optical coherence tomography

      Improvement of the dynamic range using background subtraction in single shot wide-field optical coherence tomography

      We investigated on the signal in single shot wide-field optical coherence tomographic (SS-WF-OCT) system to improve the dynamic range (DR). The SS-WF-OCT system is based on two-dimensional (2D) polarization Michelson interferometer and superluminescent diode (center wavelength of 842.5 nm) as light source. Two π-phase-shifted interferograms were acquired simultaneously using a single CCD camera and after subtraction, the en-face OCT image (area (x) 4.0 mm × (y) 4.3 mm) is obtained using 2D Hilbert transform. The OCT signal including incoherent background noises was analyzed. To improve the DR, background noise subtraction has been introduced and its measurement process ...

      Read Full Article
    10. High-resolution full-field spatial coherence gated optical tomography using monochromatic light source

      High-resolution full-field spatial coherence gated optical tomography using monochromatic light source

      We demonstrate dispersion free, high-resolution full-field spatial coherence gated optical tomography using spatially incoherent monochromatic light source. Spatial coherence properties of light source were synthesized by means of combining a static diffuser and vibrating multi mode fiber bundle. Due to low spatial coherence of light source, the axial resolution of the system was achieved similar to that of conventional optical coherence tomography which utilizes low temporal coherence. Experimental results of fringe visibility versus optical path difference are presented for varying numerical apertures objective lenses. High resolution optically sectioned images of multilayer onion skin, and red blood cells are presented.

      Read Full Article
    11. High-resolution corneal topography and tomography of fish eye using wide-field white light interference microscopy

      High-resolution corneal topography and tomography of fish eye using wide-field white light interference microscopy

      Topography and tomography of fish cornea is reconstructed using high resolution white light interference microscopy. White light interferograms at different depths were recorded by moving the object axially. For each depth position, five phase shifted interferograms were recorded and analyzed. From the reconstructed phase maps, the corneal topography and hence the refractive index was determined and from amplitude images the cross-sectional image of fish cornea was reconstructed. In the present method, we utilize a nearly common-path interference microscope and wide field illumination and hence do not require any mechanical B-scan. Therefore, the phase stability of the recorded data is improved.

      Read Full Article
    12. Quantitative phase imaging of human red blood cells using phase-shifting white light interference microscopy with colour fringe analysis

      Quantitative phase imaging of human red blood cells using phase-shifting white light interference microscopy with colour fringe analysis

      We report quantitative phase imaging of human red blood cells (RBCs) using phase-shifting interference microscopy. Five phase-shifted white light interferograms are recorded using colour charge coupled device camera. White light interferograms were decomposed into red, green, and blue colour components. The phase-shifted interferograms of each colour were then processed by phase-shifting analysis and phase maps for red, green, and blue colours were reconstructed. Wavelength dependent refractive index profiles of RBCs were computed from the single set of white light interferogram. The present technique has great potential for non-invasive determination of refractive index variation and morphological features of cells and tissues.

      Read Full Article
    13. Tomographic and volumetric reconstruction of composite materials using full-field swept-source optical coherence tomography

      Tomographic and volumetric reconstruction of composite materials using full-field swept-source optical coherence tomography

      We demonstrate tomographic and volumetric reconstruction of composite material using a full-field swept-source optical coherence tomographic (FF-SS-OCT) system. The FF-SS-OCT system is based on a co-axial and common-path optical interferometric system based on Mirau objective lens. By means of sweeping the frequency of the broad-band light source, multiple spectral interferograms are recorded and stacked in the X–Y–λ axes and processed in a computer. Optically sectioned images of the composite material at different depths are reconstructed. From the spectral interference fringe signal, the phase maps at various depths are also reconstructed. Due to its common path configuration, the present ...

      Read Full Article
    14. Transmission Mode Full-Field Swept-Source Optical Coherence Tomography for Simultaneous Amplitude and Quantitative Phase Imaging of Transparent Objects

      Transmission Mode Full-Field Swept-Source Optical Coherence Tomography for Simultaneous Amplitude and Quantitative Phase Imaging of Transparent Objects
      A transmission mode full-field swept-source optical coherence tomographic system is demonstrated for simultaneous amplitude and quantitative phase imaging of transparent objects. The experimental setup consists of a swept-source system, fiber-optic Mach–Zehnder interferometer, and an area detector. By means of sweeping the wavelength of light source, multiple interefrograms were recorded and both amplitude as well as phase images of the multilayer object and onion skin were reconstructed. The main advantages of the present system are: light passes through the sample only once; high throughput; wide field; compact; and completely nonmechanical scanning.
      Read Full Article
    15. Swept-source digital holography to reconstruct tomographic images

      Swept-source digital holography to reconstruct tomographic images
      We present what we believe to be a new method of swept-source digital holography using a superluminescent diode (SLD) as a broadband light source and an acousto-optic tunable filter (AOTF) as a frequency tunable device. The swept source consists of an SLD as a broadband source in conjunction with the AOTF as the frequency tuning device in the wavelength range of 800–870 nm. Since the AOTF is an electronically controlled device, frequency tuning can be achieved without mechanical movement . The angular spectrum approach to the scalar diffraction theory is used to reconstruct the images for each wavelength. Applications of ...
      Read Full Article
    16. Simultaneous tomography and topography of silicon integrated circuits using full-fieldswept-source optical coherence tomography

      Abstract. We demonstrate simultaneous tomography and topography of micro-electro-mechanical systems based on silicon integrated circuits using full-field swept-source optical coherence tomography. The optical set-up consists of a swept-source system, a compact Michelson interferometer, and an area detector. The swept-source system comprises a superluminescent diode as a broadband light source in conjunction with an acousto-optic tunable filter as a fast frequency tuning device. By means of sweeping the frequency of the light source, multiple interferograms were recorded and both the amplitude and the phase map of the interference fringe signal were reconstructed. Optically sectioned images of the silicon integrated circuits were ...
      Read Full Article
    17. Full-field swept-source optical coherence tomography with Gaussian spectral shaping

      Satish Kumar Dubey, Gyanendra Sheoran, Tulsi Anna et al. A swept source system was realized in the wavelength range of 810-875 nm with the combination of a broad-band superluminescent diode (SLD) and an acousto-optic tunable filter (AOTF) as a frequency-tuning device. SLD has two spectral centers at 820 nm and 845 nm with spectral bandwidth (FWHM) of arou ... [Proc. SPIE 7155, 71551F (2008)] published Fri Oct 3, 2008.
      Read Full Article
    18. Simultaneous topography and tomography of latent fingerprints using full-field swept-source optical coherence tomography

      Simultaneous topography and tomography of latent fingerprints using full-field swept-source optical coherence tomography 1 Laser Applications and Holography Laboratory, Instrument Design Development Centre, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110 016, India 2 Institute for Plasma Research, Bhat, Gandhinagar, 382428, India E-mail: dsmehta@iddc.iitd.ac.in Abstract. We demonstrate simultaneous topography and tomography of latent fingerprints using full-field swept-source opti
      Read Full Article
    19. Fingerprint detection using full-field swept-source optical coherence tomography

      Fingerprint detection using full-field swept-source optical coherence tomography Appl. Phys. Lett. 91, 181106 (2007) (3 pages) Issue Date: 29 October 2007 Satish Kumar Dubey, Tulsi Anna, Chandra Shakher, and Dalip Singh Mehta Laser Applications and Holography Laboratory, Instrument Design Development Centre, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016, India We^ report the application of full-field swept-source optical coherence tomography for^ fingerprint detection. This
      Read Full Article
    1-19 of 19
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Topics in the News

    1. (18 articles) Indian Institute of Technology at Delhi
    2. (18 articles) Dalip Singh Mehta
    3. (5 articles) Chandra Shakher
    4. (4 articles) Satish Kumar Dubey
    5. (2 articles) Nanyang Technological University
    6. (2 articles) Manabu Sato
    7. (1 articles) Yamagata University
    8. (1 articles) UCLA
    9. (1 articles) Duke University
    10. (1 articles) National Institutes of Health
    11. (1 articles) University of Melbourne
    12. (1 articles) Osaka University
    13. (1 articles) Capital Medical University
    14. (1 articles) Tokyo Medical & Dental University
    15. (1 articles) University College London
    16. (1 articles) University of Bonn
    17. (1 articles) Frank G. Holz
    18. (1 articles) Michael Pircher
  3. Popular Articles

  4. Picture Gallery

    Swept-source digital holography to reconstruct tomographic images Transmission Mode Full-Field Swept-Source Optical Coherence Tomography for Simultaneous Amplitude and Quantitative Phase Imaging of Transparent Objects Tomographic and volumetric reconstruction of composite materials using full-field swept-source optical coherence tomography High-resolution corneal topography and tomography of fish eye using wide-field white light interference microscopy Quantitative phase imaging of human red blood cells using phase-shifting white light interference microscopy with colour fringe analysis High-resolution full-field spatial coherence gated optical tomography using monochromatic light source Intravascular Imaging-Guided Percutaneous Coronary Intervention: A Universal Approach for Optimization of Stent Implantation Clinical Usefulness of a Novel Optical Coherence Tomography Procedure, “Low Molecular Weight Dextran Infusion Followed by Catheter PUSH (D-PUSH)” Optical Coherence Tomography to Guide Percutaneous Coronary Intervention of the Left Main Coronary Artery: the LEMON study Impact of optical coherence tomography findings on clinical outcomes in ST-segment elevation myocardial infarction patients: a MATRIX (Minimizing Adverse Hemorrhagic Events by Trans-radial Access Site and angioX) OCT sub-study OCTA Multilayer and Multisector Peripapillary Microvascular Modeling for Diagnosing and Staging of Glaucoma Optical coherence tomography angiography for identifying choroidal neovascular membranes: a masked study in clinical practice