Dr. Harsh Purwar Profile

Dr. Harsh Purwar

Postdoctoral Researcher at CORIA

SPIE Involvement:

Author

Websites:

Personal Website | Company Website

Publications (3)

SPIE Journal Paper | 5 March 2013 Open Access

Probing the fractal pattern and organization of Bacillus thuringiensis bacteria colonies growing under different conditions using quantitative spectral light scattering polarimetry

Paromita Banerjee, Jalpa Soni, Harsh Purwar, Nirmalya Ghosh, Tapas Sengupta

JBO, Vol. 18, Issue 03, 035003, (March 2013) https://doi.org/10.1117/12.10.1117/1.JBO.18.3.035003

KEYWORDS: Light scattering, Fractal analysis, Polarization, Bacteria, Glucose, Polarimetry, Scattering, Sodium, Spectroscopy, Multiple scattering

Read Abstract +

DOWNLOAD PAPER

SPIE Journal Paper | 12 October 2012 Open Access

Comparative study of differential matrix and extended polar decomposition formalisms for polarimetric characterization of complex tissue-like turbid media

Satish Kumar, Harsh Purwar, Razvigor Ossikovski, I. Alex Vitkin, Nirmalya Ghosh

JBO, Vol. 17, Issue 10, 105006, (October 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.10.105006

KEYWORDS: Polarization, Polarimetry, Tissues, Wave plates, Mueller matrices, Tissue optics, Birefringence, Scattering, Matrices, Monte Carlo methods

Read Abstract +

DOWNLOAD PAPER

Proceedings Article | 2 February 2012 Paper

Development and eigenvalue calibration of an automated spectral Mueller matrix system for biomedical polarimetry

Harsh Purwar, Jalpa Soni, Harshit Lakhotia, Shubham Chandel, Chitram Banerjee, Nirmalya Ghosh

Proceedings Volume 8230, 823019 (2012) https://doi.org/10.1117/12.906668

KEYWORDS: Polarization, Calibration, Wave plates, Polysomnography, Matrices, Luminescence, Polarimetry, Scattering, Tissues, Polarizers

Read Abstract +

We present a novel spectral Mueller matrix measurement system for both elastic and inelastic scattering (fluorescence) polarimetric measurements. The system comprises of a Xenon lamp as excitation source, a polarization state generator (PSG) and a polarization state analyzer (PSA) unit to generate and analyze polarization states required for 4 x 4 sample Mueller matrix measurements, coupled to a spectrometer for spectrally resolved (λ ~ 400 - 800 nm) signal detection. The PSG unit comprises of a fixed linear polarizer (polarization axis oriented at horizontal position) followed by a rotatable broadband quarter wave plate. The sample-scattered light is collected and collimated using an assembly of lenses, then passes through the PSA unit, and is finally recorded using the spectrometer. The PSA unit essentially consists of a similar arrangement as that of the PSG, but positioned in reverse order, and with the axis of the linear polarizer oriented at vertical position. A sequence of sixteen measurements are performed by changing the orientation of the fast axis of the quarter wave plates of the PSG unit (for generating the four required elliptical polarization states) and that of the PSA unit (for analyzing the corresponding polarization states). The orientation angles (35°, 70°, 105° and 140°) were chosen based on optimization of the PSG and PSA matrices to yield most stable system Mueller matrices. The performance of the polarimeter was calibrated using Eigenvalue calibration method which also yielded the actual values of the system PSG and PSA matrices at each wavelength. The system has been automated and is capable of Mueller matrix measurement with high accuracy over the entire spectral range 400 - 800 nm (elemental error < 0.01). For recording the elastic scattering Mueller matrix of sample, the PSG and PSA matrices for each wavelength are used, while for fluorescence Mueller matrix measurements, the PSG for the excitation wavelength (chosen to be 405 nm) and PSA for varying emission wavelengths (450 - 800 nm) are used. The developed spectral Mueller matrix system has been initially used to record both elastic scattering and fluorescence Mueller matrices from normal and cancerous cervical tissues.

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years