Vasu R M

Prof. Vasu R M . Professor

Contact

• E-mail : vasu@isu.iisc.ernet.in
• Office :+91-080 - 22933191, 22932889,
• Fax : +91-080- 23600135
• Residence:+91-080- 23607516

Academic Background:

• Ph. D (Aston University)

lab:

• Optical Tomography Lab

Current area of interest:

• Inverse problems in the context of structural engineering, flow diagnosis and medical imaging.

Collaborators:

• A K Nandkumaran (Mathematics)
• Debasish Roy (Civil)
• Phaneendra K Yalavarthy (SERC)
• K Rajan (Physics and Instrumentation)

           We are interested in a class of problems which is connected with the recovery of certain parameter (or property) distributions of interest of certain objects under investigation from partial and noisy sets of measurements, usually done on the boundary of the object. The data is also generated by probing the object with a radiation which innocuously penetrates the object. Examples of object under investigation are soft-tissue organs like prostrate and breast in the context of medical diagnostic imaging, bridges and similar structures in structural health monitoring. The application in the context of medical imaging is diagnosis of disease such as cancer on the basis of optical and mechanical property changes; in structural health monitoring we are interested in detecting and prognosis of possible failures in structures. Another application is quantitative flow diagnosis using light particularly to study the development and dissipation of shock in high speed flow.

            The propagation of radiation, x-ray, electro magnetic or simply a force induced displacement wave, through an object obeys certain propagation or equilibrium equations, which are usually partial differential equations (PDE). The coefficients of PDE are the property distributions of the object. The inverse problem here consists of recovery of these property distributions from boundary measurement of the basic quantity propagated.

            We pose this inverse problem as a nonlinear optimization problem (of minimizing the error between experimental and computed measurements) and solve it through either using

•   Newton-type algorithm or (b) stochastic filtering.

            The other issues addressed are (1) novel discretization strategies to reduce error in the reconstruction (2) parallelization of computing algorithms so that a near real time recovery of properties is possible.

            On the experimental side we have developed near-infrared diffuse optical tomographic imager and a photo-acoustic imaging system for imaging of breast for cancer detection. The technical issues addressed herein are the r.f modulation of laser diode, detection and demodulation of intensity modulated light exiting the boundary, fiber-assisted light delivery and collection from the object and the complete automation of the instrument using microcontrollers.

            On the numerical implementation, we are working with special purpose GPU’s and software for quick inversion of large and sparse matrices involved in the discretized descriptor of radiation propagation through the object on interest.

Previous area of research:

• Coherent and Non-Coherent optical processing
• Phase problems in optics
• X-Ray tomography

On-going Research projects:

• Development of Elastographic imaging system for early detection of cancers in human breast. (MIT)
• Application of non-invasive NIR and fiber optic techniques for bacteria detection & identification in biofluids & animal products. (DST)

Research Projects Completed:

• Development of a noncoherent image processing system (DST)
• Development of particle image velocimetry system for flow measurement
• Development of an optical tomographic microscope (DST)
• Imaging through turbid media using poalrization discrimination of ballistic light (MHRD)
• Dirction of arrival estimation of wakes using LDV(NPOL)

Courses offered:

• Digital Signal Processing (IN 225)
• Principles of tomographic imaging (IN 247)

Research Students:

• Hari.M Varma
• Sriram Chandran. R
• Sreejita Bagchi
• Sameer Biswas
• Suhesh Singh
• Saurabh Gupta 
• Jem Theresa

Supporting Staff:

1. K. K. Subramanian

Recent PhD dissertations:

• “Studies on improvement of reconstruction methods on diffuse optical tomography”, B Kanmani (2006)
• “Ulttasound assisted optical elastography for measurement of mechanical properties of soft tissues”, C Usha Devi (2006)
• “Design, fabrication and testing of a versatile and low cost diffuse optical tomographic imaging system”, R Padmaram (2007) (MS thesis)
• “New schemes for forward and inverse problems in computational mechanics and medical imaging”, Biswanath Banerjee

List of Publications:

Up-to date publication list is here:

                       
1. Title: A pseudo-dynamical systems approach to a class of inverse problems in engineering
Author(s): Banerjee B, Roy D, Vasu RM
Source: PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES   Volume: 465   Issue: 2105   Pages: 1561-1579   Published: MAY 8 2009

2. Title: A pseudo-dynamic sub-optimal filter for elastography under static loading and measurements
Author(s): Banerjee B, Roy D, Vasu RM
Source: PHYSICS IN MEDICINE AND BIOLOGY   Volume: 54   Issue: 2   Pages: 285-305   Published: JAN 21 2009

3. Title: Diffuse optical tomographic imager using a single light source
Author(s): Biswas SK, Rajan K, Vasu RM
Source: JOURNAL OF APPLIED PHYSICS   Volume: 105   Issue: 2 Article Number: 024702   Published: JAN 15 2009

4. Title: Detection of optical and mechanical property inhomogeneities in tissue mimicking phantoms using an ultrasound assisted optical probe
Author(s): Devi CU, Chandran RSB, Vasu RM, et al.
Source: JOURNAL OF BIOMEDICAL OPTICS   Volume: 13   Issue: 6 Article Number: 064025   Published: NOV-DEC 2008

5. Title: Quantitative photoacoustic tomography from boundary pressure measurements: noniterative recovery of optical absorption coefficient from the reconstructed absorbed energy map
Author(s): Banerjee B, Bagchi S, Vasu RM, et al.
Source: JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION   Volume: 25   Issue: 9   Pages: 2347-2356   Published: SEP 2008

6. Title: Implementation of a phase array diffuse optical tomographic imager
Author(s): Rajan K, Vijayakumar V, Biswas SK, et al.
Source: REVIEW OF SCIENTIFIC INSTRUMENTS   Volume: 79   Issue: 8 Article Number: 084301   Published: AUG 2008

7. Title: Measurement of visco-elastic properties of breast-tissue mimicking materials using diffusing wave spectroscopy
Author(s): Devi CU, Chandran RSB, Vasu RM, et al.
Source: JOURNAL OF BIOMEDICAL OPTICS   Volume: 12   Issue: 3 Article Number: 034035   Published: MAY-JUN 2007

8. Title: Mechanical property assessment of tissue-mimicking phantoms using remote palpation and optical read-out for amplitude of vibration and refractive index modulation
Author(s): Devi CU, Chandran RSB, Vasu RM, et al.
Source: JOURNAL OF BIOMEDICAL OPTICS   Volume: 12   Issue: 2 Article Number: 024028   Published: MAR-APR 2007

11. Title: Computationally efficient optical tomographic reconstructions through waveletizing the normalized quadratic perturbation equation - art. no. 61640R
Author(s): Kanmani B, Bansal PB, Vasu RM
Conference Information: 2005 Saratov Fall Meeting, SEP 27-30, 2005 Saratov, RUSSIA
Source: Saratov Fall Meeting 2005: Coherent Optics of Ordered and Random Media VI  Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)   Volume: 6164   Pages: R1640-R1640   Published: 2006

12. Title: Elimination of cross-talk in diffuse optical tomographic reconstructions through a weighted update procedure: results of simulation study - art. no. 61640S
Author(s): Kanmanil B, Vasu RM
Conference Information: 2005 Saratov Fall Meeting, SEP 27-30, 2005 Saratov, RUSSIA
Source: Saratov Fall Meeting 2005: Coherent Optics of Ordered and Random Media VI  Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)   Volume: 6164   Pages: S1640-S1640   Published: 2006

13. Title: Application of ultrasound-tagged photons for measurement of amplitude of vibration of tissue caused by ultrasound: theory, simulation, and experiments (vol 11, pg 4, 2006)
Author(s): Devi CU, Vasu RM, Sood AK
Source: JOURNAL OF BIOMEDICAL OPTICS   Volume: 11 Issues: 4 Article Number: 049802   Published: JUL-AUG 2006

14. Title: Quantitative flow visualization in supersonic jets through tomographic inversion of wavefronts estimated through shadow casting
Author(s): Thayyullathil H, Vasu RM, Kanhirodan R
Source: APPLIED OPTICS   Volume: 45   Issue: 20   Pages: 5010-5019   Published: JUL 10 2006

15. Title: Application of ultrasound-tagged photons for measurement of amplitude of vibration of tissue caused by ultrasound: theory, simulation, and experiments
Author(s): Devi CU, Vasu RM, Sood AK
Source: JOURNAL OF BIOMEDICAL OPTICS   Volume: 11   Issue: 3 Article Number: 034019   Published: MAY-JUN 2006

16. Title: Diffuse optical tomography through solving a system of quadratic equations: theory and simulations
Author(s): Kanmani B, Vasu RM
Source: PHYSICS IN MEDICINE AND BIOLOGY   Volume: 51   Issue: 4   Pages: 981-998   Published: FEB 21 2006

17. Title: Diffuse optical tomography through solving a system of quadratic equations without re-estimating the derivatives: the "Frozen-Newton" method; Reconstruction from experimental data
Author(s): Kanmani B, Padmaram R, Vasu RM
Conference Information: 2004 Saratov Fall Meeting, SEP 21-24, 2004 Saratov, RUSSIA
Source: Saratov Fall Meeting 2004: Coherent Optics of Ordered and Random Media V Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)   Volume: 5772   Pages: 170-180 Published: 2005

18. Title: Experimental determination of optical and mechanical properties of an optical elastography phantom
Author(s): Amma CUD, Vasu RM, Sood AK
Conference Information: 2004 Saratov Fall Meeting, SEP 21-24, 2004 Saratov, RUSSIA
Source: Saratov Fall Meeting 2004: Coherent Optics of Ordered and Random Media V Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)   Volume: 5772   Pages: 210-218 Published: 2005

19. Title: Design, fabrication, and characterization of a tissue-equivalent phantom for optical elastography
Author(s): Devi CU, Vasu RM, Sood AK
Source: JOURNAL OF BIOMEDICAL OPTICS   Volume: 10   Issue: 4 Article Number: 044020   Published: JUL-AUG 2005

20. Title: Experimental investigation of perturbation Monte-Carlo based derivative estimation for imaging low-scattering tissue
Author(s): Yalavarthy PK, Karlekar K, Patel HS, et al.
Source: OPTICS EXPRESS   Volume: 13   Issue: 3   Pages: 985-997   Published: FEB 7 2005
21. Title: Diffuse optical tomography using intensity measurements and the a priori acquired regions of interest: theory and simulations
Author(s): Kanmani B, Vasu RM
Source: PHYSICS IN MEDICINE AND BIOLOGY   Volume: 50   Issue: 2   Pages: 247-264   Published: JAN 21 2005

22. Title: Reconstruction of optical properties of low-scattering tissue using derivative estimated through perturbation Monte-Carlo method
Author(s): Kumar YP, Vasu RM
Source: JOURNAL OF BIOMEDICAL OPTICS   Volume: 9   Issue: 5   Pages: 1002-1012   Published: SEP-OCT 2004

23. Title: Three-dimensional optical tomographic imaging of supersonic jets through inversion of phase data obtained through the transport-of-intensity equation
Author(s): Thayyullathil H, Langoju R, Padmaram R, et al.
Source: APPLIED OPTICS   Volume: 43   Issue: 21   Pages: 4133-4141   Published: JUL 20 2004

24. Title: Perturbation Monte-Carlo based derivative estimation for imaging transport regime tissue optical properties
Author(s): Kumar YP, Karlekar K, Vasu RM
Conference Information: 11th International Conference on Advanced Laser Technologies, SEP 19-23, 2003 Cranfield Univ, Silsoe, ENGLAND
Source: ALT'03 INTERNATIONAL CONFERENCE ON ADVANCED LASER TECHNOLOGIES: BIOMEDICAL OPTICS  Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)   Volume: 5486   Pages: 77-84   Published: 2003

25. Title: Diffuse tomographic imaging, after estimation of location and approximate value of the object inhomogeneities through backprojection of the data
Author(s): Buddhi K, Vasu RM
Conference Information: 2003 Saratov Fall Meeting, OCT 07-10, 2003 Saratov, RUSSIA
Source: SARATOV FALL MEETING 2003: COHERENT OPTICS OF ORDERED AND RANDOM MEDIA IV  Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)   Volume: 5475   Pages: 108-114   Published: 2003

26. Title: Perturbation Monte-Carlo based derivative estimation for imaging low-scattering inclusions in a heterogeneous tissue
Author(s): Kumar YP, Vasu RM
Conference Information: Conference on Convergent Technologies for the Asia-Pacific Region (TENCON 2003), OCT 15-17, 2003 Bangalore, INDIA
Source: IEEE TENCON 2003: CONFERENCE ON CONVERGENT TECHNOLOGIES FOR THE ASIA-PACIFIC REGION, VOLS 1-4  Book Series: TENCON-IEEE Region 10 Conference Proceedings   Pages: 529-533   Published: 2003

27. Title: Imaging in turbid media by modified filtered back projection method using data from Monte Carlo simulation
Author(s): Aggarwal A, Vasu RM
Conference Information: Conference on Smart Nondestructive Evaluation and Health Monitoring of Structural and Biological Systems II, MAR 03-05, 2003 SAN DIEGO, CA
Source: SMART NONDESTRUCTIVE EVALUATION AND HEALTH MONITORING OF STRUCTURAL AND BIOLOGICAL SYSTEMS II  Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)   Volume: 5047   Pages: 314-324   Published: 2003

28. Title: Direct measurement of phase of forward-scattered light using polarization heterodyne interferometry
Author(s): Chandan GG, Vasu RM, Asokan S
Conference Information: Advanced Photonic Sensors and Applications II Conference, NOV 27-30, 2001 SINGAPORE, SINGAPORE
Source: ADVANCED PHOTONIC SENSORS AND APPLICATIONS II  Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)   Volume: 4596   Pages: 280-286   Published: 2001

29. Title: Tomographic imaging of phase objects in turbid media through quantitative estimate of phase of ballistic light
Author(s): Chandan GG, Vasu RM, Asokan S
Source: OPTICS COMMUNICATIONS   Volume: 191   Issue: 1-2   Pages: 9-14   Published: MAY 1 2001

31. Title: An extended Kalman filter based reconstruction approach to curved ray optical tomography
Author(s): Naik N, Vasu RM
Conference Information: International Conference on Optics and Optoelectronics '98, DEC 09-12, 1998 DEHRADUM, INDIA
Source: SELECTED PAPER FROM INTERNATIONAL CONFERENCE ON OPTICS AND OPTOELECTRONICS '98 - SILVER JUBILEE SYMPOSIUM OF THE OPTICAL SOCIETY OF INDIA  Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)   Volume: 3729   Pages: 153-157   Published: 1999

32. Title: A wavelet based multiresolution extended Kalman filter approach to the reconstruction problem of curved ray optical tomography
Author(s): Naik N, Vasu RM
Conference Information: Conference on High-Speed Imaging and Sequence Analysis, JAN 28-29, 1999 SAN JOSE, CA
Source: HIGH-SPEED IMAGING AND SEQUENCE ANALYSIS  Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)   Volume: 3642   Pages: 156-165   Published: 1999

33. Title: Wavelet based compression and denoising of optical tomography data
Author(s): Nath SK, Vasu RM, Pandit M
Source: OPTICS COMMUNICATIONS   Volume: 167   Issue: 1-6   Pages: 37-46   Published: AUG 15 1999

34. Title: Non-interferometric methods of phase estimation for application in optical tomography
Author(s): Datta GK, Vasu RM
Source: JOURNAL OF MODERN OPTICS   Volume: 46   Issue: 9   Pages: 1377-1388   Published: JUL 20 1999

35. Title: A hybrid optical-digital processor for image deblurring
Author(s): Kumar SR, Boopathi V, Vasu RM
Source: OPTICS AND LASER TECHNOLOGY   Volume: 28   Issue: 2   Pages: 143-149   Published: MAR 1996

36. Title: DEBLURRING IN A NONCOHERENT OPTICAL-PROCESSING SYSTEM - PUPIL FUNCTION SYNTHESIS AND EXPERIMENTAL IMPLEMENTATION
Author(s): VASU RM, BOOPATHI V
Source: OPTICAL ENGINEERING   Volume: 33   Issue: 6   Pages: 1953-1961   Published: JUN 1994

37. Title: ENHANCEMENT OF FAR-FIELD SPATIAL COHERENCE OF A PARTIALLY COHERENT-LIGHT SOURCE BY SOURCE MASKING
Author(s): BOOPATHI V, VASU RM, RAO LK
Source: APPLIED OPTICS   Volume: 32   Issue: 23   Pages: 4410-4414   Published: AUG 10 1993

38. Title: COHERENT OPTICAL-PROCESSING USING NONCOHERENT LIGHT AFTER SOURCE MASKING
Author(s): BOOPATHI V, VASU RM
Source: APPLIED OPTICS   Volume: 31   Issue: 2   Pages: 186-191   Published: JAN 10 1992

39. Title: MULTIPLE IMAGING WITH AN ABERRATION OPTIMIZED HOLOLENS ARRAY
Author(s): KUMAR AS, VASU RM
Source: OPTICAL ENGINEERING   Volume: 28   Issue: 8   Pages: 903-908   Published: AUG 1989

40. Title: IMAGING WITH ORIENTED PHOTOGRAPHIC DIFFUSERS
Author(s): KUMAR AS, VASU RM
Source: OPTICS COMMUNICATIONS   Volume: 70   Issue: 2   Pages: 77-81   Published: FEB 15 1989

41. Title: MULTIPLEXING IN MULTIPLE IMAGING THROUGH THE THETA MODULATION TECHNIQUE
Author(s): KUMAR AS, VASU RM
Source: OPTICS COMMUNICATIONS   Volume: 66   Issue: 1   Pages: 6-7   Published: APR 1 1988

42. Title: MULTIPLE IMAGING AND MULTICHANNEL OPTICAL-PROCESSING WITH SPLIT LENSES
Author(s): KUMAR AS, VASU RM
Source: APPLIED OPTICS   Volume: 26   Issue: 24   Pages: 5345-5349   Published: DEC 15 1987

43. Title: GENERATION OF OPTIMUM RANDOM PINHOLE ARRAYS FOR MULTIPLE IMAGING
Author(s): KUMAR AS, VASU RM
Source: APPLIED OPTICS   Volume: 26   Issue: 18   Pages: 3858-3861   Published: SEP 15 1987

44. Title: THE DYNAMICS OF A MODE-LOCKED AND FREQUENCY-DOUBLED LASER
Author(s): VASU RM, REDDY KPJ
Source: PRAMANA   Volume: 20   Issue: 1   Pages: 55-64   Published: 1983

45. Title: IMAGE DEBLURRING WITH COMPUTER GENERATED DOUBLE PHASE HOLOGRAMS
Author(s): VASU RM, ROGERS GL
Source: PATTERN RECOGNITION   Volume: 14   Issue: 1-6   Pages: 297-303   Published: 1981

46. Title: DEBLURRING WITH A POSITIVE ONLY FILTER AFTER FURTHER BLURRING
Author(s): VASU RM, ROGERS GL
Source: OPTICS COMMUNICATIONS   Volume: 35   Issue: 2   Pages: 175-178   Published: 1980

 47. Title: CONSTRUCTION OF A PHASE-INVERTING GRATING AND ITS USE IN A DEBLURRING FILTER
Author(s): VASU RM, ROGERS GL
Source: APPLIED OPTICS   Volume: 19   Issue: 3   Pages: 469-473   Published: 1980