1. Articles from tulsi anna

    1-10 of 10
    1. Elucidation of microstructural changes in leaves during senescence using spectral domain optical coherence tomography

      Elucidation of microstructural changes in leaves during senescence using spectral domain optical coherence tomography

      Leaf senescence provides a unique window to explore the age-dependent programmed degradation at organ label in plants. Here, spectral domain optical coherence tomography (SD-OCT) has been used to study in vivo senescing leaf microstructural changes in the deciduous plant Acer serrulatum Hayata . Hayata leaves show autumn phenology and change color from green to yellow and finally red. SD-OCT image analysis shows distinctive features among different layers of the leaves; merging of upper epidermis and palisade layers form thicker layers in red leaves compared to green leaves. Moreover, A-scan analysis showed a significant (p < 0.001) decrease in the attenuation coefficient ...

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      Mentions: Wen-Chuan Kuo
    2. A Feasibility Study of Broadband White Light Emitting Diode (WLED) based Full-Field Optical Coherence Microscopy (FF-OCM) using Derivative-based Algorithm

      A Feasibility Study of Broadband White Light Emitting Diode (WLED) based Full-Field Optical Coherence Microscopy (FF-OCM) using Derivative-based Algorithm

      Developing cost-effective and fast detection methods in full-field optical coherence microscopy (FF-OCM) platform for biological applications is of prime focus today. In this paper, we report a cost-effective Linnik type FF-OCM system with a single broadband white light emitting diode (WLED) (470-850nm, λ0=630nm) light source in conjunction with a derivative-based image reconstruction algorithm. Sequential two-dimensional (2D) multiple phase-shifted interferograms were obtained by moving the sample stage using piezoelectric transducer (PZT) and recorded via a 2D charge complementary oxide semiconductor (CMOS) camera. Subsequently, the en-face sectional images were reconstructed using a derivative-based algorithm. The measured axial and lateral resolutions along ...

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    3. En-face sectional imaging using single-shot full-field optical coherence tomography (SS-FF-OCT) based on white light emitting diode (WLED)

      En-face sectional imaging using single-shot full-field optical coherence tomography (SS-FF-OCT) based on white light emitting diode (WLED)

      This work reports a Linnik type single shot full-field optical coherence tomography (SS-FF-OCT), which uses a fast generalized analytic signal based complex Riesz transform scheme to reconstruct wide area en-face OCT images. The OCT interferometer is illuminated using a single broad band white light emitting diode (WLED) (wavelength range 470- 850nm, central wavelength 650nm) and detection unit is a two-dimensional (2D) charge complementary metal oxide semiconductor (CMOS) camera. The measured axial and lateral resolution (using 4x, NA=0.1 microscope objective) of the present system is 0.9μm and 3.9μm, very close to theoretical values. The measured ...

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      Mentions: Wen-Chuan Kuo
    4. 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 ...

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    5. 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 ...

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    6. 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 ...

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    7. 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.
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    8. 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 ...
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    9. 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.
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    10. 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
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    1-10 of 10
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  2. Topics in the News

    1. (7 articles) Indian Institute of Technology at Delhi
    2. (6 articles) Dalip Singh Mehta
    3. (4 articles) Chandra Shakher
    4. (3 articles) Wen-Chuan Kuo
    5. (2 articles) Manabu Sato
    6. (2 articles) Satish Kumar Dubey
    7. (2 articles) Harbin Medical University
    8. (1 articles) Yamagata University
    9. (1 articles) National Yang-Ming University
    10. (1 articles) Nankai University
    11. (1 articles) Medical University of Vienna
    12. (1 articles) Kawasaki Medical School
    13. (1 articles) Stefan G. Sacu
    14. (1 articles) Hector M. Garcia-Garcia
    15. (1 articles) Bo Yu
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    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 Improvement of the dynamic range using background subtraction in 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 En-face sectional imaging using single-shot full-field optical coherence tomography (SS-FF-OCT) based on white light emitting diode (WLED) A Feasibility Study of Broadband White Light Emitting Diode (WLED) based Full-Field Optical Coherence Microscopy (FF-OCM) using Derivative-based Algorithm Elucidation of microstructural changes in leaves during senescence using spectral domain optical coherence tomography OCT parameters of the optic nerve head and the retina as surrogate markers of brain volume in a normal population, a pilot study Choroidal vessel density in unilateral hyperopic amblyopia using en-face optical coherence tomography Association between food and nutrients intakes and coronary plaque vulnerability in patients with coronary heart disease: An optical coherence tomography study Optical Coherence Tomography based treatment approach for patients with Acute Coronary Syndrome Using OCT Fixation Shift to Assess Eccentric Fixation in Children With Residual Amblyopia