Prof. Dalip Singh Mehta

Prof. Dalip Singh Mehta
Department of Physics
Indian Institute of Technology Delhi
Tel:+91-11-2659 1455 (O)
Fax:+91-11-2658 1114

Research Interests:

Bio-photonics: Optical Coherence tomography and Optical Tweezers, Optical 3D-surface profilometry, Solid State Lighting (Optics of LEDs and OLEDs) and Optical Interferometry.

About Prof. Dalip Singh Mehta

Dr. D. S. Mehta is currently a Professor at the Department of Physics, Indian Institute of Technology Delhi. Previously, he worked as Associate Professor and Assistant Professor (June 2002 - Dec. 2012) at the Instrument Design Development Centre, Indian Institute of Technology Delhi. Before Joining the Institute he was JSPS Post Doctoral Fellow (July 2000 – June 2002) at the University of Electro-communications, Tokyo, Japan, Post Doctoral Fellow (Nov. 1999 – May 2000), National Dong Hwa University, Taiwan, Research Associate, NPL, New Delhi, STA Post Doctoral Fellow (June 1997 – May 1998), NIRE, Tsukuba, Japan and UNESCO Research Fellow (Jan. 1996 – Sept.1996), Tokyo Institute of Technology Tokyo, Japan. He has been actively working in the areas of Bio-photonics (Optical Coherence Tomography and Optical Tweezers), Green Photonics (LEDs and OLEDs) and Optical Metrology and contributed 80 refereed journal publications and 95 papers in conferences.

Selected recent publications:
A. Biophotonics:- Optical Coherence Tomography and Optical Tweezers:

  1. V. Srivastava, S. Nandy, and D. S. Mehta, High-resolution corneal topography and tomography of fish eye using wide-field white light interference microscopy, Applied Physics Letters 102, 153701 (2013)
  2. D. S. Mehta, and V. Srivastava, “Quantitative phase imaging of human red blood cells using phase-shifting white light interference microscopy with colour fringe analysis,” Applied Physics Letters 101, 203701 (2012).
  3. D. S. Mehta, Dinesh N. Naik, R. Singh, and M. Takeda, “Laser speckle reduction by multimode optical fiber bundle with combined temporal, spatial, and angular diversity,” APPLIED OPTICS 51 (2012) 1894-1904.
  4. V. Srivastava, T. Anna, and D. S. Mehta, “Single shot quantitative imaging of biological cells using low coherence off-axis interferometric Hilbert phase microscopy,” Journal of Optics (IOP) Vol. 14, 125707 (2012).
  5. V. Srivastava, T.Anna, M.Sudan and D.S. Mehta, Tomographic and volumetric reconstruction of composite materials using full-field swept-source optical coherence tomography,” Meas. Sci. Technol. 23 (2012) 055203 (10pp). (Also appeared in OCT News: /tomographic-and-volumetric-recon struction -of-compo/).
  6. Tulsi Anna, Vishal Srivastava, Dalip Singh Mehta and Chandra Shakher, “High-resolution full-field optical coherence microscopy using a Mirau interferometer for the quantitative imaging of biological cells”, APPLIED OPTICS, Vol. 50, No. 34 (2011) 6343. Also Appeared in Virtual Journal of Biomedical Optics: vjbo/abstract.cfm? URI=ao-50-34-6343.
  7. T. Anna, V. Srivastava, C. Shakher, and D.S. Mehta, “Transmission Mode Full-Field Swept-Source Optical Coherence Tomography for Simultaneous Amplitude and Quantitative Phase Imaging of Transparent Objects”, IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 23, NO. 13, JULY 1, 2011 899 – 901. (Also appeared in OCT news,
  8. V. Srivastava, M. Sudan, Tulsi Anna, and D. S. Mehta, “Common-path spectral-domain optical low coherence interferometric system for the measurement of small changes in refractive index of Liquid Crystal cell” Accepted for Publication in Optics and Lasers in Engineering.
  9. S. K. Dubey, T. Anna, C. Shakher and D. S. Mehta, “Fingerprint detection using full-field swept-source optical coherence tomography,” Applied Physics Letters 91, 181106 (2007).
  10. R. Kumar, D. S. Mehta, S. Saraswati, and C. Shakher, Probing of Ehrlich Ascites Carcinoma Cell Using in situ Aggregates of Au_NPs as SERS Label Created by Plasmon Exciting Hybrid_ Laser Mode1, Laser Physics, 2012, Vol. 22, No. 2, pp.461–468.
  11. Ranjeet Kumar, Chandra Shakher and D.S. Mehta, “Clustering of optically trapped large diameter plasmonic Au-NPs by laser beam of hybrid- mode” J. Nanophotonics, Vol. 5, 053511-17, 2011.
  12. R. Kumar, C. Shakher and D.S. Mehta, “3D multiple optical trapping of Au-nanoparticles and prokaryote E. coli using intra-cavity generated non-circular beam of inhomogeneous intensity”, Laser Physics, Vol 20 (60), (2010), 1514 -1524.
  13. R. Kumar, C. Shakher and D. S. Mehta, “Compact interferometric optical tweezer for patterned trapping and manipulation of polystyrene spheres and SWCNTs”, J. Mod. Optics, Vol. 57 (13), 1157 – 1162 (2010).
  14. D. S. Mehta, C. Y. Lee and A. Chiou, “Multipoint parallel excitation and CCD based imaging system for high-throughput fluorescence detection of biochip micro-arrays,” Opt. Commun.190, 59 (2001).
  15. C. C. Huang, C. F. Wang, D. S. Mehta and A. Chiou, “Optical tweezers as sub-pico-newton force transducers,” Opt. Commun. 195, 41 (2001).

Solid State Lighting (LEDs and OLEDs): Green Photonics

  1. A. Kumar, Ritu Srivastava, M.N. Kamalasanan and D. S. Mehta, “Enhancement of light extraction efficiency of organic light emitting diodes using nano-structured indium tin oxide”, Optics Letters Vol. 37, 575-578 (2012).
  2. D. S. Mehta, K. Saxena, S. K. Dubey and C. Shakher, “Coherence characteristics of light-emitting diodes”, Journal of Luminescence 130 (2010) 96–102.
  3. K. Saxena, D. S. Mehta, R. Srivastava and M. N. Kamalasanan, “Spatial coherence properties of electroluminescence from Alq3-based organic light-emitting diodes,”Applied Physics Letters 89, 061124 (2006).
  4. Rakhi Grover, R. Srivastava, G. Chauhan1, M. N. Kamalasanan and D. S. Mehta, “White electro-luminescence from hybrid organic inorganic LEDs based on thermally evaporated nanocrystals,” Euro Physics Letters 99 (2012) 17003.
  5. Gyanendra Singh and D. S. Mehta, “Photoluminescence studies of organic phosphor coated diffusing surface using blue inorganic light emitting diode as excitation source”, Journal of Optics (IOP) 15, 025710-8 (2013).
  6. G. Singh, and D. S. Mehta, “Measurement of change in refractive index in polymeric flexible substrates using wide field interferometry and digital fringe analysis”, Applied Optics 51, 8413-8422 (2012).
  7. K. Saxena, V.K. Jain and D. S. Mehta, “A review on the light extraction techniques in organic electroluminescent devices,” Optical Materials 32 (2009) 221–233.
  8. A. Kumar, J. Prakash, D. S. Mehta, A. M. Biradar, and W. Haase, “Enhanced photoluminescence in gold nanoparticles doped ferroelectric liquid crystals,” Applied Physics Letters 95, 023117 (2009) (3 pages).
  9. J. Prakash, A. Choudhary, A. Kumar, D. S. Mehta and A. M. Biradar, “Nonvolatile memory effect based on gold nanoparticles doped ferroelectric liquid crystal,” Applied Physics Letters 93, 112904 (2008).
  10. J. Prakash, A. Choudhary, D. S. Mehta, and A. M. Biradar “Effect of carbon nanotubes on response time of ferroelectric liquid crystal” Phys. Rev. E 80 (2009) 012701.

Optical 3D-surface Profilometry and Optical Interferometry:

  1. D. S. Mehta, S. K. Dubey, M. M. Hossain and C. Shakher, “Simple multi-frequency and phase-shifting fringe projection system based on two-wavelength lateral shearing interferometry for three-dimensional profilometry,” Applied Optics 44, 7515 (2005).
  2. D. S. Mehta, S. K. Dubey, C. Shakher and M. Takeda, “Two-wavelength Talbot effect and its application for three-dimensional step-height measurement,” Applied Optics 45, 7602 (2006).
  3. D. S. Mehta, P. Singh, M. S. Faridi, S. Mirza and C. Shakher, “Distance measurement with extended range using lateral shearing interferometry and Fourier transform fringe analysis,” Optical Engineering 44, 636021 (2005).
  4. D. S. Mehta, P. Singh, M. S. Faridi, S. Mirza and C. Shakher, “Two-wavelength lateral shearing interferometry,” Optical Engineering 44, 85603 (2005).
  5. D. S. Mehta, H. Hinosugi, S. Saito, M. Takeda, T. Kurokawa, H. Takahashi, M. Ando, M. Shishido and T. Yoshizawa, “A spectral interferometric microscope using tandem liquid-crystal Fabry-Perot interferometers for the extension of the dynamic range in three-dimensional step-height measurement,” Applied Optics 42, 682 (2003).
  6. D. S. Mehta, S. Saito, H. Hinosugi, M. Takeda and T. Kurokawa, “Spectral interference Mirau microscope for three-dimensional surface profilometry with an acousto-optic tunable filter,” Applied Optics 42, 1296 (2003).
  7. D. S. Mehta, M. Sugai, H. Hinosugi, S. Saito, M. Takeda, T. Kurokawa, H. Takahashi, M. Ando, M. Shishido and T. Yoshizawa, “Simultaneous three-dimensional step-height measurement and high-resolution tomographic imaging using spectral interferometric microscope,” Applied Optics 41, 3874 (2002).
  8. D. S. Mehta, H. C. Kandpal, K. Saxena, J.S. Vaishya and K. C. Joshi, “Displacement measurements from coherence-induced spectral changes in the Mach-Zehnder interferometer,” Opt. Commun., 119, 352 (1995).
  9. D. S. Mehta and, H. C. Kandpal, “A Simple method for testing laser beam collimation,” Opt. and Laser Techn., 29, 469 (1997).
  10. T. Anna, C. Shakher and D. S. Mehta, “Simultaneous tomography and topography of silicon integrated circuits using full-field swept-source optical coherence tomography,” J. Opt. A: Pure Appl. Opt. 11, 045501 (2009). (Also appeared in OCT news,
  11. T. Anna, S. K. Dubey, C. Shakher, A. Roy and D. S. Mehta, “Sinusoidal fringe projection system based on compact and non-mechanical scanning low-coherence Michelson interferometer for three-dimensional shape measurement,” Opt. Commun. 282, 1237 (2009).