Welcome to the Optical Metrology and Imaging Laboratory (OMIL) at IIT Kanpur. Our goal is to develop novel optical techniques for precision metrology. The relevant application areas include surface characterization, 3D shape sensing, non-destructive inspection and biological cell imaging.
I am Prof. Gannavarpu Rajshekhar. I am jointly affiliated with the Department of Electrical Engineering and Center for Lasers and Photonics at IIT Kanpur.
Education
PhD, Photonics (2009-2012)
Swiss Federal Institute of Technology Lausanne (EPFL), Switzerland
Master of Technology, Laser Technology (2006-2008)
Indian Institute of Technology, Kanpur, India
Bachelor of Engineering, Electronics and Telecommunication
Engineering (2001-2005)
Government Engineering College Raipur (now NIT Raipur), Pt. Ravishankar
Shukla University, Raipur, India
Experience
Professor (2023-present)
Department of Electrical Engineering, IIT Kanpur
Associate Professor (2018-2022)
Department of Electrical Engineering, IIT Kanpur
Assistant Professor (2014-2018)
Department of Electrical Engineering, IIT Kanpur
Swiss National Science Foundation Postdoctoral Fellow
(2013-2014)
Beckman Institute, University of Illinois at Urbana-Champaign, USA
Postdoctoral Researcher (2012-2013)
Applied Computing and Mechanics Laboratory, EPFL, Switzerland
Awards and Honors
Service
Teaching
Undergraduate Courses
Postgraduate Courses
Area
We work in the domain of optical coherent imaging. Here, we are mainly interested in quantitatively measuring the phase of the optical wave-field scattered from an object or specimen. We work on both the experimental and computational aspects of coherent imaging.
The experimental techniques being investigated in the lab involve:
The computational research involves the development of robust signal processing techniques in optical imaging. Some relevant problems include:
Applications
Phd
M.Tech
PhD
M.Tech
MSR
Subrahmanya Keremane Narayan and Rajshekhar Gannavarpu, Simultaneous estimation of multiple order phase derivatives using deep learning method in digital holographic interferometry, Optics and Lasers in Engineering, 184 (1), 108583, 2025
Dhruvam Pandey and Rajshekhar Gannavarpu, Deep learning assisted state space method for phase derivative estimation in digital holographic interferometry, Optics Continuum, 3 (9), 1765-1779, 2024
Viren S Ram and Rajshekhar Gannavarpu, Fringe pattern normalization using conditional Generative Adversarial Networks, Optik, 313, 171999, 2024
Subrahmanya Keremane Narayan, Dhruvam Pandey, Allaparthi Venkata Satya Vithin, and Rajshekhar Gannavarpu, Robust method to process nonuniform intensity holograms in digital holographic microscopy for nanoscale surface metrology, Applied Optics, 62 (32), 8497-8505, 2023
Dhruvam Pandey, Abhinav Saini, and Rajshekhar Gannavarpu, Non-contact automated defect detection using a deep learning approach in diffraction phase microscopy, Optics Continuum, 2 (11), 2421-2435, 2023
Subrahmanya Keremane Narayan, Allaparthi Venkata Satya Vithin, Sreeprasad Ajithaprasad and Rajshekhar Gannavarpu, Surface profile measurement using nonlinear optimization approach in diffraction phase microscopy, Optics and Laser Technology, 167, 109723, 2023
Subrahmanya Keremane Narayan, Allaparthi Venkata Satya Vithin, and Rajshekhar Gannavarpu, Deep learning assisted non-contact defect identification method using diffraction phase microscopy, Applied Optics, 62 (20), 5433-5442, 2023
Dhruvam Pandey and Rajshekhar Gannavarpu, Nanoscale surface profile measurement using state space approach in digital holographic microscopy, Surface Topography: Metrology and Properties, 11 (2), 024001, 2023
Allaparthi Venkata Satya Vithin and Rajshekhar Gannavarpu, Quantitative phase gradient metrology using diffraction phase microscopy and deep learning, Journal of the Optical Society of America A, 40(3), 611-619, 2023
Allaparthi Venkata Satya Vithin, Jagadesh Ramaiah, and Rajshekhar Gannavarpu, Deep learning based single shot multiple phase derivative retrieval method in multi-wave digital holographic interferometry, Optics and Lasers in Engineering, 162, 107442, 2023
Jagadesh Ramaiah, Tullio de Rubeis, Rajshekhar Gannavarpu and Dario Ambrosini, Quantitative flow visualization by hidden grid background oriented schlieren, Optics and Lasers in Engineering, 160, 107307, 2023
Dhruvam Pandey, Jagadesh Ramaiah, Sreeprasad Ajithaprasad and Rajshekhar Gannavarpu, Subspace analysis based machine learning method for automated defect detection from fringe patterns, Optik, 270, 170026, 2022
Jagadesh Ramaiah and Rajshekhar Gannavarpu, Multiple phase extraction using graphics processing unit assisted unitary transformation method in digital holographic interferometry, Applied Optics, 61 (28), 8180-8189, 2022
Allaparthi Venkata Satya Vithin, Ankur Vishnoi, and Rajshekhar Gannavarpu, Phase derivative estimation in digital holographic interferometry using a deep learning approach, Applied Optics, 61 (11), 3061-3069, 2022
Anik Ghosh, Rishikesh Kulkarni and Rajshekhar Gannavarpu, Phase unwrapping algorithm using breadth-first-search and multi-level segmentation of phase quality interval in digital holography, Journal of Modern Optics, 69(16), 957-967, 2022
Jagadesh Ramaiah, Ankur Vishnoi, and Rajshekhar Gannavarpu, Non-invasive surface profile measurement using a unitary transformation subspace approach in digital holography, Optics Continuum, 1 (4), 684-696, 2022
Shikha Sharma, Rishikesh Kulkarni, Ankur Vishnoi and Rajshekhar Gannavarpu, Wrapped phase denoising using adaptive Kalman smoother algorithm, Journal of Modern Optics, 69 (15), 838-849, 2022
Jagadesh Ramaiah and Rajshekhar Gannavarpu, Dynamic displacement measurement in digital holographic interferometry using eigenspace analysis, Applied Optics, 60 (33), 10468-10476, 2021
Dhruvam Pandey, Jagadesh Ramaiah and Rajshekhar Gannavarpu, Fast measurement of phase and its derivatives in digital holographic interferometry using graphics processing unit assisted state space method, Optik, 248, 168172, 2021
Shikha Sharma, Rishikesh Kulkarni, Sreeprasad Ajithaprasad and Rajshekhar Gannavarpu, Fringe pattern normalization algorithm using Kalman filter, Results in Optics, 5, 100152, 2021
Jagadesh Ramaiah and Rajshekhar Gannavarpu, Non-invasive deformation metrology using subspace analysis in digital holographic interferometry, Measurement Science and Technology, 32 (12), 125201, 2021
Ankur Vishnoi and Rajshekhar Gannavarpu, Single shot quantitative phase gradient estimation using Wigner-Ville distribution in digital holographic microscopy, Optics Continuum, 4 (9), 2452-2459, 2021 (Selected as Editor’s Pick)
Ankur Vishnoi, Aditya Madipadaga, Sreeprasad Ajithaprasad and Rajshekhar Gannavarpu, Automated defect identification from carrier fringe patterns using Wigner–Ville distribution and a machine learning-based method, Applied Optics, 60 (15), 4391-4397, 2021
Allaparthi Venkata Satya Vithin, Ankur Vishnoi and Rajshekhar Gannavarpu, Demodulation of noisy interferograms with rapid phase variations and amplitude fluctuations using a surrogate principle-based optimization method, Applied Optics, 60 (7), 1937-1942, 2021
Allaparthi Venkata Satya Vithin, Issac Show, Sreeprasad Ajithaprasad and Rajshekhar Gannavarpu, Demodulating interferograms with non-uniform amplitude variations for precision non-contact optical profilometry, Optics and Lasers in Engineering, 134, 106292, 2020
Sreeprasad Ajithaprasad, Jagadesh Ramaiah and Rajshekhar Gannavarpu, Dynamic noncontact surface profilometry using a fast eigenspace method in diffraction phase microscopy, Applied Optics, 59 (19), 5796-5802, 2020
Jagadesh Ramaiah, Sreeprasad Ajithaprasad, Rajshekhar Gannavarpu and Dario Ambrosini, Fast and robust method for flow analysis using GPU assisted diffractive optical element based background oriented schlieren (BOS), Optics and Lasers in Engineering, 126, 105908, 2020
Allaparthi Venkata Satya Vithin, Sreeprasad Ajithaprasad, and Rajshekhar Gannavarpu, Step phase reconstruction using an anisotropic total variation regularization method in a diffraction phase microscopy, Applied Optics, 58 (26), 7189-7194, 2019
Jagadesh Ramaiah, Sreeprasad Ajithaprasad and Rajshekhar Gannavarpu, Graphics processing unit assisted diffraction phase microscopy for fast non-destructive metrology, Measurement Science and Technology, 30 (12), 125202, 2019
Ankur Vishnoi, Sreeprasad Ajithaprasad and Rajshekhar Gannavarpu, Wigner–Ville distribution based diffraction phase microscopy for non-destructive testing, Journal of Modern Optics, 66 (16), 1644-1651, 2019
Ankur Vishnoi and Rajshekhar Gannavarpu, Rapid deformation analysis in digital holographic interferometry using graphics processing unit accelerated Wigner–Ville distribution, Applied Optics, 58 (16), 4420-4424, 2019 (Selected as Editor’s Pick)
Ankur Vishnoi, Jagadesh Ramaiah, and Rajshekhar Gannavarpu, Phase recovery method in digital holographic interferometry using high-resolution signal parameter estimation, Applied Optics, 58, 1485-1490, 2019
Sreeprasad Ajithaprasad, Raviteja Velpula and Rajshekhar Gannavarpu, Defect detection using windowed Fourier spectrum analysis in diffraction phase microscopy, Journal of Physics Communications, 3, 025006, 2019
Jagadesh Ramaiah and Rajshekhar Gannavarpu, Single shot multiple phase retrieval in digital holographic interferometry using subspace processing, Optics and Lasers in Engineering, 111, 201-205, 2018
Rajshekhar Gannavarpu and Dario Ambrosini, Multi-scale approach for analyzing convective heat transfer flow in background-oriented Schlieren technique, Optics and Lasers in Engineering, 110, 415-419, 2018
Sreeprasad Ajithaprasad and Rajshekhar Gannavarpu, Non-invasive precision metrology using diffraction phase microscopy and space-frequency method, Optics and Lasers in Engineering, 109, 17-22, 2018
Jagadesh Ramaiah, Pramod Rastogi and Rajshekhar Gannavarpu, Demodulation of moire fringes in digital holographic interferometry using an extended Kalman filter, Applied Optics, 57, 1944-1949, 2018
Lihong Ma, Rajshekhar Gannavarpu, Ru Wang, Basanta Bhaduri, Shamira Sridharan, Mustafa Mir, Arindam Chakraborty, Rajashekar Iyer, Supriya Prasanth, Larry Millet, Martha U Gillette, Gabriel Popescu, Phase correlation imaging of unlabeled cell dynamics, Nature Scientific Reports, 6, 32702, 2016
Rajshekhar Gannavarpu, Basanta Bhaduri, Krishna Tangella and Gabriel Popescu, Spatiotemporal characterization of a fibrin clot using quantitative phase imaging, PLOS ONE, 9(11), e111381, 2014.
Rajshekhar Gannavarpu, Basanta Bhaduri, C. Edwards, R. Zhou, L. L. Goddard and Gabriel Popescu, Nanoscale topography and spatial light modulator characterization using wide-field quantitative phase imaging, Optics Express, 22(3), 3432-3438, 2014.
Rajshekhar Gannavarpu and Pramod Rastogi, Phase estimation using a state-space approach based method, Optics and Lasers in Engineering, 51(8), 1004-1007, 2013.
Rajshekhar Gannavarpu and Pramod Rastogi, Fringe demodulation using the two-dimensional phase differencing operator, Optics Letters, 37(20), 4278-4280, 2012.
Rajshekhar Gannavarpu and Pramod Rastogi, Multiple signal classification technique for phase estimation from a fringe pattern, Applied Optics, 51(24), 5869-5875, 2012.
Rajshekhar Gannavarpu and Pramod Rastogi, Fringe analysis: Premise and perspectives, Optics and Lasers in Engineering, 50(8), iii-x, 2012.
Rajshekhar Gannavarpu, Saisiva Gorthi and Pramod Rastogi, Detection of defects from fringe patterns using a pseudo Wigner-Ville distribution based method, Optics and Lasers in Engineering, 50(8), 1059-1062, 2012.
Rajshekhar Gannavarpu, Saisiva Gorthi and Pramod Rastogi, Estimation of multiple phases from a single fringe pattern in digital holographic interferometry, Optics Express, 20(2), 1281-1291, 2012.
Saisiva Gorthi, Rajshekhar Gannavarpu and Pramod Rastogi, Three dimensional shape measurement using high-order instantaneous moments based fringe projection method, Optics and Laser Technology, 43 (1), 40-44, 2011.
Rajshekhar Gannavarpu and Pramod Rastogi, Application of complex-lag distributions for estimation of arbitrary order phase derivatives in digital holographic interferometry, Optics Letters, 36(19), 3738-3740, 2011.
Rajshekhar Gannavarpu, Saisiva Gorthi, and Pramod Rastogi, Simultaneous measurement of in-plane and out-of-plane displacement derivatives using dual-wavelength digital holographic interferometry, Applied Optics, 50(34), H16-H21, 2011.
Rajshekhar Gannavarpu, Saisiva Gorthi and Pramod Rastogi, Simultaneous multidimensional deformation measurements using digital holographic moiré, Applied Optics, 50(21), 4189-4197, 2011.
Rajshekhar Gannavarpu, Saisiva Gorthi and Pramod Rastogi, Estimation of dynamically varying displacement derivatives using fringe projection technique, Applied Optics, 50(3), 282-286, 2011.
Rajshekhar Gannavarpu, Saisiva Gorthi and Pramod Rastogi, Estimation of displacement derivatives in digital holographic interferometry using a two-dimensional space-frequency distribution, Optics Express, 18(17), 18041-18046, 2010.
Saisiva Gorthi, Rajshekhar Gannavarpu and Pramod Rastogi, Strain estimation in digital holographic interferometry using piecewise polynomial phase approximation based method, Optics Express, 18(2), 560-565, 2010.
Rajshekhar Gannavarpu, Saisiva Gorthi and Pramod Rastogi, Estimation of phase derivative using adaptive window spectrogram, Journal of Optical Society of America A, 27(1), 69-75, 2010.
Saisiva Gorthi, Rajshekhar Gannavarpu and Pramod Rastogi, Investigation to realize a computationally efficient implementation of the high-order instantaneous-moments-based fringe analysis method, Optical Engineering, 49 (6), 065802-065802-4, 2010
Rajshekhar Gannavarpu, Saisiva Gorthi and Pramod Rastogi, Polynomial Wigner-Ville distribution based method for direct phase derivative estimation from optical fringes, Journal of Optics A: Pure and Applied Optics, 11(12), 125402, 2009.
Rajshekhar Gannavarpu, Saisiva Gorthi and Pramod Rastogi, Strain, curvature and twist measurements in digital holographic interferometry using pseudo Wigner-Ville distribution based method, Review of Scientific Instruments, 80, 093107, 2009.
Rajshekhar Gannavarpu, Saisiva Gorthi and Pramod Rastogi, Adaptive window Wigner-Ville distribution based method to estimate phase derivative from optical fringes, Optics Letters, 34(20), 3151-3153, 2009.
Dhruvam Pandey, Viren S Ram, and Rajshekhar Gannavarpu, “Neural network based subspace analysis for estimation of phase derivatives from noisy interferograms”. Digital Holography and Three-Dimensional Imaging, Paestum, Italy, M2A.2, 2024.
Subrahmanya Keremane Narayan, Dhruvam Pandey and Rajshekhar Gannavarpu, “Non-destructive Surface Defect Metrology using Deep Learning and Diffraction Phase Microscopy”. Optica Imaging Congress, Toulouse, France, CTh4B.7, 2024.
Dhruvam Pandey, Subrahmanya Keremane Narayan and Rajshekhar Gannavarpu, “Deep learning-based automated defect detection in digital holographic microscopy”. Optica Imaging Congress, Toulouse, France, JF2A.4, 2024.
D. Ambrosini, A. Ciccozzi, T. de Rubeis, Viren S. Ram and Rajshekhar Gannavarpu, “Background-oriented schlieren improved by machine learning for studying convective flows”. 41st UIT International Heat Transfer Conference, Napoli, Italy, 2024.
Subrahmanya Keremane Narayan, Allaparthi Venkata Satya Vithin, and Rajshekhar Gannavarpu, “Non-contact topography using quadratic optimization approach in diffraction phase microscopy”, Frontiers in Optics, Washington, USA, FD1.5, 2023
Subrahmanya Keremane Narayan, Viren S Ram, and Rajshekhar Gannavarpu, “Conditional generative modelling based fringe pattern normalization”, Optica Imaging Congress, Digital Holography and Three-Dimensional Imaging, Boston, USA, JWA2A.25, 2023
Dhruvam Pandey, K N Subrahmanya and Rajshekhar Gannavarpu, “Nanoscale surface topography using low cost digital holographic microscopy”, Proceedings SPIE 12618, Optical Measurement Systems for Industrial Inspection XIII, 126180Z, Munich, Germany, 2023
Dario Ambrosini, Tullio de Rubeis, Domenica Paoletti, Jagadesh Ramaiah, Rajshekhar Gannavarpu, “Hidden Grid Background Oriented Schlieren in studying convective flows”, Journal of Physics: Conference Series, 2509, Heat Transfer Conference, Italy, 2023
Dhruvam Pandey and Rajshekhar Gannavarpu, “Fringe Pattern Defect Identification Using Kalman Filter and Machine Learning”, Digital Holography and Three-Dimensional Imaging, OSA Imaging and Applied Optics Congress, Cambridge, United Kingdom, W2A.6, 2022
Allaparthi Venkata Satya Vithin, Jagadesh Ramaiah, Dhruvam Pandey and Rajshekhar Gannavarpu, “Displacement Derivative Analysis Using Deep Learning in Digital Holographic Interferometry”, Digital Holography and Three-Dimensional Imaging, OSA Imaging and Applied Optics Congress, Cambridge, United Kingdom, W2A.7, 2022
Allaparthi Venkata Satya Vithin and Rajshekhar Gannavarpu, “Estimation of phase derivative with sharp variations in digital holography using total variational regularization”, Digital Holography and Three-Dimensional Imaging, OSA Imaging and Applied Optics Congress, Washington DC, USA, JTh6A.33, 2021
Allaparthi Venkata Satya Vithin and Rajshekhar Gannavarpu, “Robust method for fringe demodulation under rapid phase and amplitude fluctuations”, Digital Holography and Three-Dimensional Imaging, OSA Imaging and Applied Optics Congress, Washington DC, USA, JTh6A.32, 2021
Jagadesh Ramaiah and Rajshekhar Gannavarpu, “Defect localization in noisy fringe patterns using subspace method and naive Bayes classifier”, Digital Holography and Three-Dimensional Imaging, OSA Imaging and Applied Optics Congress, Washington DC, USA, JTh6A.31, 2021
Allaparthi Venkata Satya Vithin, Issac Show, Sreeprasad Ajithaprasad, and Gannavarapu Rajshekhar, “Demodulation of fringe patterns corrupted by non uniform intensity variations in dynamics studies”, Proceedings SPIE 11552, Optical Metrology and Inspection for Industrial Applications VII, 115521Z, 2020
Jagadesh Ramaiah and Rajshekhar Gannavarpu, “Dynamic fringe analysis using GPU assisted root-MUSIC method”, Proceedings SPIE 11552, Optical Metrology and Inspection for Industrial Applications VII, 1155206, 2020
Aditya Madipadaga and Rajshekhar Gannavarpu, “Investigation of temporally varying fringe pattern defects using machine learning for optical metrology”, Proceedings SPIE 11552, Optical Metrology and Inspection for Industrial Applications VII, 115520L, 2020
Ankur Vishnoi and Rajshekhar Gannavarpu, “Fast fringe analysis method using graphics processing unit acceleration for dynamic fault identification”, Proceedings SPIE 11352, Optics and Photonics for Advanced Dimensional Metrology, 113520J, 2020
Sreeprasad Ajithaprasad, Vigneshwar Rajendran and Rajshekhar Gannavarpu, ” A GPU assisted space frequency method for dynamic defect detection in optical metrology”, Proceedings SPIE 11205, Seventh International Conference on Optical and Photonic Engineering (icOPEN 2019) Thailand, 1120526, 2019
Sreeprasad Ajithaprasad, Jagadesh Ramaiah and Rajshekhar Gannavarpu, “Dynamic deformation analysis using diffraction phase microscopy and space-frequency analysis”, 4th edition of the IEEE Workshop on Recent Advances in Photonics (WRAP) 2019, Indian Institute of Technology (IIT), Guwahati, India
Sreeprasad Ajithaprasad, Jagadesh Ramaiah and Rajshekhar Gannavarpu, “Non-contact optical surface profilometry using diffraction phase microscopy and subspace method”, International Conference on Optics and electro-optics (ICOL) 2019, Instruments Research and Development Establishment (IRDE), Dehradun, Uttarakhand, INDIA
Ankur Vishnoi and Rajshekhar Gannavarpu, “High speed non-destructive testing method using digital holographic interferometry”, International Conference on Optics and electro-optics (ICOL) 2019, Instruments Research and Development Establishment (IRDE), Dehradun, Uttarakhand, INDIA
Sreeprasad Ajithaprasad, Rajshekhar Gannavarpu, “Laser assisted defect detection using diffraction phase microscopy and space frequency analysis”, National Photonics Symposium 2019, International School of Photonics, Cochin, India
Ankur Vishnoi, Jagadesh Ramaiah, Rajshekhar Gannavarpu, “Phase derivative estimation in digital holography interferometry using multiple signal classification method”, The International Conference on Fiber Optics and Photonics - PHOTONICS, IIT Delhi, 2018
Jagadesh Ramaiah, Rajshekhar Gannavarpu, “Fringe analysis using extended Kalman filter and matrix enhancement techniques”, The International Conference on Fiber Optics and Photonics - PHOTONICS, IIT Delhi, 2018
Sreeprasad Ajithaprasad, Rajshekhar Gannavarpu, “Nanoscale non-destructive measurement of surface profile using diffraction phase microscopy and windowed Fourier transform”, The International Conference on Fiber Optics and Photonics - PHOTONICS, IIT Delhi, 2018
Lihong Ma, Rajshekhar Gannavarpu, Ru Wang, Basanta Bhaduri, Shamira Sridharan, Mustafa A Mir, Arindam Chakraborty, Supriya G Prasanth, Larry Millet, Martha U Gillette, Gabriel Popescu, “Phase correlation imaging (PCI) for cell dynamics investigation”, Proc. SPIE 9718, Quantitative Phase Imaging II, 97180P, USA , 2016.
Dario Ambrosini and Rajshekhar Gannavarpu, “Quantitative schardin’s schlieren 2 in heat and mass transfer studies”, International Conference on Combined Digital Optical & Imaging Methods applied to Mechanical Engineering, Ascona, Switzerland, 2016
Rajshekhar Gannavarpu, Basanta Bhaduri, Krishnarao Tangella, and Gabriel Popescu, “Three-dimensional fractal structure of a blood clot using quantitative phase imaging”, Digital Holography and Three-Dimensional Imaging, Seattle, USA, DM4B.4, 2014.
Rajshekhar Gannavarpu, Basanta Bhaduri, Chris Edwards, Renjie Zhou, Lynford Goddard, and Gabriel Popescu, “Wide-field diffraction phase microscope for precision metrology”, Digital Holography and Three-Dimensional Imaging, Seattle, USA, DTh1B.2, 2014.
Rajshekhar Gannavarpu and Pramod Rastogi, “Measuring phase derivatives in digital holographic interferometry”, Digital Holography and Three-Dimensional Imaging, Seattle, USA, DTh1B.1, 2014.
Rajshekhar Gannavarpu, Sai Siva Gorthi, and Pramod Rastogi, “Comparative Analysis of Various Single-tone Frequency Estimation Techniques in High-order Instantaneous Moments Based Phase Estimation Method”, AIP Conference Proceedings, 1236, 355-358, 2010.
Saisiva Gorthi, Rajshekhar Gannavarpu, and Pramod Rastogi, “Estimation of Phase in Fringe Projection Technique Using High-order Instantaneous Moments Based Method”, AIP Conference Proceedings, 1236, 359-362, 2010.
Dr. Rajshekhar Gannavarpu
ACES 325B
Department of Electrical Engineering
IIT Kanpur
Kanpur-208016, Uttar Pradesh, India
Email: gshekhar@iitk.ac.in
Phone: +91-512-259-6477