Dr. Gyanendra Sheoran Profile

Dr. Gyanendra Sheoran

at National Institute of Technology Delhi

SPIE Involvement:

Author | Special Event Speaker

Publications (7)

Proceedings Article | 7 June 2024 Presentation + Paper

Enhanced wide-field off-axis holography based on intensity correlation

Amit Yadav, Gyanendra Sheoran, Takamasa Suzuki, Rakesh Kumar Singh

Proceedings Volume 13041, 1304104 (2024) https://doi.org/10.1117/12.3013634

KEYWORDS: Digital holography, Speckle, Image enhancement, Biomedical optics, Polarization

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Proceedings Article | 15 August 2023 Poster + Paper

Shape measurement of phase objects using fringe projection technique

V. Trivedi, M. Joglekar, S. Utadiya, N. Chhiller, S. Sharma, G. Sheoran, A. Anand

Proceedings Volume 12618, 126182S (2023) https://doi.org/10.1117/12.2673865

KEYWORDS: Fringe analysis, Phase measurement, Phase distribution, Modulation, Geometrical optics, 3D metrology, Refractive index, Optical components

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SPIE Journal Paper | 26 November 2019

Numerical three-step phase-shifting microwave holography

Vineeta Kumari, Neelam Barak, Gyanendra Sheoran

OE, Vol. 58, Issue 11, 114107, (November 2019) https://doi.org/10.1117/12.10.1117/1.OE.58.11.114107

KEYWORDS: Holograms, Phase shifts, Microwave radiation, Holography, Antennas, Phase shifting, Optical engineering, Waveguides, Directional couplers, Scattering

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SPIE Journal Paper | 2 April 2018

Development and analysis of anatomically real breast phantoms using different dispersion models

Vineeta Kumari, Gyanendra Sheoran, Tirupathiraju Kanumuri, Ritesh Vyas, S. Avinash Rao

JEI, Vol. 27, Issue 05, 051208, (April 2018) https://doi.org/10.1117/12.10.1117/1.JEI.27.5.051208

KEYWORDS: Tissues, Breast, Dielectrics, Magnetic resonance imaging, 3D modeling, Image segmentation, Data modeling, Microwave imaging, 3D image processing, Image processing

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An effective method to develop anatomically real numerical breast phantoms for T1-weighted MR images of different tissue densities is presented. The dielectric properties for breast tissues are calculated and analyzed using different dispersion models (i.e., one- and two-pole cole–cole and Debye models). The method presented in this paper propounds significant improvements in comparison with existing MRI-based numerical phantoms in terms of denoising of images, tissue segmentation, nonlinear mapping of dielectric properties with realistic shapes using all the dispersion models and densitywise classification of phantoms. This method is a multistep approach in which each MRI voxel is mapped with the appropriate dielectric properties according to different dispersion models. The MRI data was collected and interpolated according to the size of the uniform grid for finite difference time domain computations followed by the preprocessing of MR images to enhance them. Thereafter, the voxel intensities were segregated into two groups as adipose and fibro glandular tissues. These tissue intensities were assigned the corresponding dielectric properties. Three-dimensional (3-D) numerical phantoms were created according to all the dispersion models. After the comparison among the models, it has been found that, along with frequency, the dielectric properties vary according to the variation of the dispersion model parameters. It was also observed that the dielectric properties calculated from one-pole cole–cole and two-pole Debye models are more close to the real properties of breast tissues than other models. A generalized method has been defined for developing the 3-D phantoms for all classes of breast according to the inhomogeneity of fibroglandular tissues using the dispersion models. The frequency-dependent and dispersion model parameters-dependent dielectric properties have been assigned to the phantoms. These real-like phantoms after 3-D printing would help researchers working in the field of breast cancer detection studies.

Proceedings Article | 3 October 2008 Paper

Measurement of temperature field in steady laminar free convection flow using digital holography

Chandra Shakher, Md. Mosarraf Hossain, Dalip Singh Mehta, Gyanendra Sheoran

Proceedings Volume 7155, 71551X (2008) https://doi.org/10.1117/12.814570

KEYWORDS: Digital holography, Temperature metrology, Convection, Holograms, Interferometry, Fourier transforms, Speckle, Holographic interferometry, Holography, 3D image reconstruction

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Proceedings Article | 3 October 2008 Paper

Full-field swept-source optical coherence tomography with Gaussian spectral shaping

Satish Kumar Dubey, Gyanendra Sheoran, Tulsi Anna, Arun Anand, Dalip Singh Mehta, Chandra Shakher

Proceedings Volume 7155, 71551F (2008) https://doi.org/10.1117/12.814551

KEYWORDS: Optical coherence tomography, Signal detection, Glasses, Sensors, Light sources, Refractive index, Charge-coupled devices, Optical filters, Superluminescent diodes, Tunable filters

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Proceedings Article | 3 October 2008 Paper

Reduction of speckle noise in digital holographic images using wavelet transform

Akshay Sharma, Gyanendra Sheoran, Z. Jaffery, . Moinuddin

Proceedings Volume 7155, 71551L (2008) https://doi.org/10.1117/12.814558

KEYWORDS: Digital holography, Signal to noise ratio, Speckle, Holograms, 3D image reconstruction, Image filtering, Wavelets, Digital filtering, Holography, Fourier transforms

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Showing 5 of 7 publications

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