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Ray tracing based path-length calculations for polarized light tomographic imaging

Manjappa, Rakesh and Kanhirodan, Rajan (2015) Ray tracing based path-length calculations for polarized light tomographic imaging. In: Conference on Polarization Science and Remote Sensing VII, AUG 11-12, 2015, San Diego, CA.

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Official URL: http://dx.doi.org/10.1117/12.2189190


A ray tracing based path length calculation is investigated for polarized light transport in a pixel space. Tomographic imaging using polarized light transport is promising for applications in optical projection tomography of small animal imaging and turbid media with low scattering. Polarized light transport through a medium can have complex effects due to interactions such as optical rotation of linearly polarized light, birefringence, diattenuation and interior refraction. Here we investigate the effects of refraction of polarized light in a non-scattering medium. This step is used to obtain the initial absorption estimate. This estimate can be used as prior in Monte Carlo (MC) program that simulates the transport of polarized light through a scattering medium to assist in faster convergence of the final estimate. The reflectance for p-polarized (parallel) and s-polarized (perpendicular) are different and hence there is a difference in the intensities that reach the detector end. The algorithm computes the length of the ray in each pixel along the refracted path and this is used to build the weight matrix. This weight matrix with corrected ray path length and the resultant intensity reaching the detector for each ray is used in the algebraic reconstruction (ART) method. The proposed method is tested with numerical phantoms for various noise levels. The refraction errors due to regions of different refractive index are discussed, the difference in intensities with polarization is considered. The improvements in reconstruction using the correction so applied is presented. This is achieved by tracking the path of the ray as well as the intensity of the ray as it traverses through the medium.

Item Type: Conference Proceedings
Series.: Proceedings of SPIE
Additional Information: Copy right for this article belongs to the SPIE-INT SOC OPTICAL ENGINEERING, 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA
Keywords: Polarization; refraction; tomography; ray tracing; modeling; image reconstruction; algebraic reconstruction method
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 14 Jan 2016 04:28
Last Modified: 14 Jan 2016 04:28
URI: http://eprints.iisc.ac.in/id/eprint/53107

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