Polarization Sensitive Optical Imaging and Characterization of Soybean Using Stokes- Mueller Matrix Model

Light polarimetry is a useful tool by which to analyze the modification in the shape and orientation of the field vectors of the electromagnetic radiation which propagates through scattering medium. Among the methods available to analyze turbid media, the use of polarized light has attracted much attention recently, as it has been discovered that multiply scattered photons still maintain partial polarization. [1-4] A typical experiment entails launching a known polarization state in light into a turbid sample and measuring the polarization properties of the reemitted light. The detected signal depends on many variables, including the number and nature of scattering events, the incident polarization state, and the detection geometry. [5-7] In the past few years, several groups have shown how polarization sensitive scattering measurements can be used to measure certain properties of turbid medium such as the average particle size, [8] scattering coefficient, anisotropy factor of particle suspensions , [9] optical material characterization, [10-11] and the study of biological materials. [11-13] An optical polarizers and retarders are rotated to provide additional incident and analyzed polarization states to enable the reconstruction of the 2-D Mueller matrix of various biological sample [14-15]. It has also been shown that the benefits of using polarized light can be combined with different optical modalities. For example, the benefit of using of polarized light in optical coherence tomography (OCT) measurements can significantly improve image contrast. [16-17] Furthermore, the measurement of polarization parameters of the light scattered benefits from a relatively simple, fast, and convenient data acquisition procedure, [18-19] which motivates the ongoing efforts aimed at further developing the scattering polarization imaging technology. If some of the light retained its polarization properties upon multiple scattering at 1800 transmittion mode and this effect could be quantified and exploited, potentially useful measurements could be made in almost any clinical situation. Since light in the visible and infrared regions of the electromagnetic spectrum is not harmful to biological tissues at moderate flounce levels, has a penetration depth of several millimeters, and has a reasonable chance of scattering out of the tissue and being detected, it would be ideal for making noninvasive measurements. Other practical reasons for studying the behavior of light at 180° would be for the possibility of spatial imaging to map out the locations of sample structures and compositions, and to gain a better general understanding of turbid systems. [20-22]