Varma, H.

Dr. Hari Varma
Associate Professor

Phone: +(91-22) 2576 7705
E-mail: harivarma [at]
Location: Room No. 203, BSBE Building 
Lab website

Research Interest

  • Developing novel optical tools for medical imaging applications.
  • Laser speckle contrast imaging and diffuse correlation spectroscopy/tomography for blood flow measurements.
  • Inverse problems in medical imaging:  Theoretical and computational aspects of diffuse optical tomography.

Academic Background

  • 2003: B.Tech (Instrumentation), Cochin University of Science and Technology (CUSAT), Kerala
  • 2006: M. Sc(Engg.) (Instrumentation), Indian Institute of Science (IISc), Bangalore
  • 2010: PhD (Instrumentation), Indian Institute of Science (IISc), Bangalore

Professional Experience

  • Post-Doctoral Fellow: Inverse Problem Research Group, Dept. of Mathematics, Aalto University, Helsinki, Finland. (2010-2011)
  • Post-Doctoral Fellow: Medical Optics Group, Institute of Photonic Sciences (ICFO), Barcelona, Spain. (2012-2015)


  • Ramalingaswamy Re-entry Fellowship 2014-2015, Department of Biotechnology (DBT), India


  • Paul, Ria, K. Murali, Sumana Chetia, and Hari M. Varma. “A simple algorithm for diffuse optical tomography (DOT) without matrix inversion.” Biomed. Phys. Eng. Express  8 (2022) 045001
  • Murali, K. and Hari M. Varma “Multi-speckle diffuse correlation spectroscopy to measure cerebral blood flow.” Biomedical optics express 11 (2020): 6699–6709.
  • Murali, K., A. K. Nandakumaran, and Hari M. Varma. “On the equivalence of speckle contrast-based and diffuse correlation spectroscopy methods in measuring in vivo blood flow.” Optics Letters 45.14 (2020): 3993-3996.
  • Murali, K., A. K. Nandakumaran, Turgut Durduran, and Hari M. Varma. “Recovery of the diffuse correlation spectroscopy data-type from speckle contrast measurements: towards low-cost, deep-tissue blood flow measurements.” Biomedical optics express 10, no. 10 (2019): 5395-5413.
  • Dragojević, Tanja, Hari M. Varma, Joseph L. Hollmann, Claudia P. Valdes, Joseph P. Culver, Carles Justicia, and Turgut Durduran. “High-density speckle contrast optical tomography (SCOT) for three dimensional tomographic imaging of the small animal brain.” NeuroImage 153 (2017): 283-292.
  • Dragojevic, D.Bronzi,H.M.Varma, C.P.Valdes, C.Castellvi, F. Villa, A.Tosi, C.Justicia, F.Zappa, T.Durduran , High-speed multi-exposure laser speckle contrast imaging with a single-photon counting camera,” Biomedical Optics Express 6, 2865-2876 (2015).
  • M. Varma, C. P. Valdes, A. K. Kristoffersen, J. P. Culver, and T. Durduran, Speckle contrast optical tomography: A new method for deep tissue three-dimensional tomography of blood flow ,” Biomedical Optics Express5, 1275-1289 (2014).
  • P. Valdes, H. M. Varma, A. K. Kristoffersen, J. P. Culver, and T. Durduran, Speckle contrast optical spectroscopy for measuring blood flow in deep tissues,” Biomedical Optics Express5, 2769-2784 (2014).
  • d. l. Rosa, l. Cervera, A. Kristoffersen, C. Valdes, H. M. Varma, C. Justicia, T. Durduran, A Chamorro, and A. Planas, Mannose-binding lectin promotes local microvascular thrombosis after transient brain ischemia in mice,” Stroke45, 1453-1459(2014).
  • Hyvonen, A. K. Nandakumaran, H. M. Varma, and R. M. Vasu, Generalized eigenvalue decomposition of the field autocorrelation in correlation diffusion of photons in turbid media,” Mathematical Methods in the Applied Sciences36, 1447-1458 (2013).
  • M. Varma, R.M. Vasu, and A. K. Nandakumaran, Convergence analysis of the Newton algorithm and a pseudo-time marching scheme for diffuse correlation tomography,” Journal of Optical Society of America A27, 259-267 (2010). 
  • M. Varma, R.M. Vasu, and A. K. Nandakumaran, Study of turbid media with light: Recovery of mechanical and optical properties from boundary measurement of intensity autocorrelation of light,” Journal of Optical Society of America A26, 1472-1483 (2009).
  • M. Varma, B. Banerjee, A. K. Nandakumaran, R. M. Vasu, and D. Roy, Pseudo-time marching schemes for inverse problems in structural health assessment and medical imaging,” Current Science97, 1220-1226 (2009). 
  • M. Varma, R.M. Vasu, and A. K. Nandakumaran, Direct reconstruction of complex refractive index distribution from boundary measurement of intensity and normal derivative intensity,” Journal of Optical Society of America A24, 3089-3099 (2007).