Depolarization Index Research Articles

Mueller matrix polarimetry for characterization of E-Beam irradiated Uhmwpe

Along with existing spectroscopic methods for polymer characterization, continuous efforts are in progress to have more sensitive and simple method for accurate determination of polymer characteristics before and after its modification with the use of various techniques. As an example the chemical and physical changes in biocompatible materials are usually probed with FTIR spectroscopy which uses totally un-polarized light and sophisticated proper aliened optics. It is therefore, for aforementioned objective, a more sensitive, better, and a simple experimental technique was proposed that mainly utilize the polarized light and simple Mueller Marix calculus for inquiring oxidation degradation and degree of cross-linking of irradiated UHMWPE. Mueller Matrix calculus was used for extracting the Depolarization Indices of 30, 65, and 100 kGy irradiated compressed sheets of UHMWPE. The effect of absorbed dose on depolarization index (DI) was monitored over the optical spectral range i.e. from 400 nm to 800 nm. A significant increase i.e. from 0.5 to 0.8 in DI values was observed in lower wavelength regions, however; slight increase was there in higher wavelength region. Radiation induced chemical changes including C=O, C=C unsaturation and voids within the UHMWPE structure along with scattering events because of increase in % crystallinity were attributed for the behavior in lower wavelength region. Scattering events due to increase in degradation because of oxidation or radiation induced defects were the reason for behavior in longer wavelength regime. In addition to this, integrated area under the DI curve and oxidation index of each sample had linear relation with each other. The results reported in this study suggested that the degradation/modification in UHMWPE can be probed with more sensitive physical quantity of light i.e. its polarization state.

Single-incidence polarimetry for optical characteristics

In this paper, we propose a simplified measurement called single-incidence polarimetry measurement (SPM) to obtain optical characteristics such as di-attenuationP, variation of phase difference Δ and depolarization index d on material surface. Compared with tradition Mueller matrix polarimetry which needs multiple (at least 4) Stokes vectors as incidences in experiments, SPM only needs single polarized light as incidence, which simplifies experimental procedures tremendously and increases experimental efficiency. In addition, SPM is suitable for complicated materials such as thick lump samples, uneven surfaces, powder and liquid which are not available on traditional ellipsometers, e.g., the variable-angle spectroscopic ellipsometer (VASE) produced by J. A. Woollam Company. The objectivity and lower complexity of SPM are verified by the contrast experiments with Mueller matrix polarimetry. The advantage that SPM is more suitable for complicated experimental condition is demonstrated by the contrast experiments with VASE. All the analyses and discussions are realized by the root mean squared error (RMSE) between referenced values and experimental results. In conclusion, SPM can realize low-cost and easy-assembled measurements on complicated and depolarized surfaces rather than obtaining higher precision data on smooth and thin surfaces. In the aspect of efficiency and convenience, SPM is useful to analyze optical characteristics qualitatively.

Three-dimensional nonlinear Stokes–Mueller polarimetry

The formalism is developed for a tree-dimensional ($3D$) nonlinear Stokes-Mueller polarimetry. The expressions are derived for the generalized $3D$ linear and nonlinear Stokes vectors, and the corresponding nonlinear Mueller matrix. The coherency-like Hermitian square matrix $X$ of susceptibilities is introduced, which is derived from the nonlinear Mueller matrix. The $X$-matrix is characterized by the index of depolarization. Several decompositions of the $X$-matrix are introduced. The $3D$ nonlinear Stokes-Mueller polarimetry formalism can be applied for three and higher wave mixing processes. The $3D$ polarimetric measurements can be used for structural investigations of materials, including heterogeneous biological structures. The $3D$ polarimetry is applicable for nonlinear microscopy with high numerical aperture objectives.

Characterization of healthy and nonmelanoma-induced mouse utilizing the Stokes-Mueller decomposition.

Skin cancer is one of the most common cancers, including melanoma and nonmelanoma cancer. Melanoma can be easily detected by the observation of abnormal moles, but nonmelanoma signs and symptoms are not apparent in the early stages. We use the Stokes-Mueller matrix decomposition method to detect nonmelanoma at the early stage by decomposing the characteristics of polarized light interacting with normal and cancerous tissues. With this decomposition method, we extract nine optical parameters from biological tissues, namely the LB orientation angle (α), the LB phase retardance (β), the CB optical rotation angle (γ), the LD orientation angle (θd), the linear dichroism (D), the circular dichroism (R), the degrees of linear depolarization (e1 and e2), the degree of circular depolarization (e3), and the depolarization index (Δ). The healthy skin and the induced nonmelanoma skin cancer of mice are analyzed and compared based on their optical parameters. We find distinctive ranges of values for normal skin tissue and nonmelanoma skin cancer, in which β and D in cancerous tissue are larger and nonmelanoma skin becomes less depolarized. This research creates an innovative solid foundation for the diagnosis of skin cancer in the future.

Scanned Laser Pico Projection and Stokes-Mueller Matrix Imaging Polarimetry for Detecting Cancer Cells With Different Cytoskeletal Organizations and Metastatic Potencies

The scanned laser pico-projection (SLPP) method and Stokes–Mueller matrix polarimetry technique are used to distinguish cancer cells with different cytoskeletal organizations and metastatic potencies. The speckle contrast of human bone osteosarcoma cancer cells (U2OS) with different cytoskeletal drug treatments is measured by the SLPP method. The results show that the contrast is directly related to the organization of the microtubules and actin fibers. The Stokes–Mueller matrix polaimetry technique is employed to measure polarization parameters of the same samples. The measurement results are found to be consistent with those obtained using the SLPP method. Finally, the Stokes–Mueller matrix polaimetry technique is used to extract the polarization parameters of cell-pairs with different metastatic potencies. It is shown that the extracted value of the linear phase retardance (β) is particularly sensitive to the organization of the microtubules and actin fibers. Furthermore, the linear phase retardance (β) and depolarization index (Δ) are both sensitive to the metastatic potency of the cancer cells. In general, both techniques provide a rapid, noninvasive and label-free approach for distinguishing cancer cells with different cytoskeleton organizations and metastatic potentials, and are thus of significant benefit in evaluating the malignancy of cancer cells.

On-chip spatiotemporal electrophysiological analysis of human stem cell derived cardiomyocytes enables quantitative assessment of proarrhythmia in drug development

We examined a simultaneous combined spatiotemporal field potential duration (FPD) and cell-to-cell conduction time (CT) in lined-up shaped human embryonic stem cell-derived cardiomyocytes (hESC-CMs) using an on-chip multielectrode array (MEA) system to evaluate two origins of lethal arrhythmia, repolarization and depolarization. The repolarization index, FPD, was prolonged by E-4031 and astemizole, and shortened by verapamil, flecainide and terfenadine at 10 times higher than therapeutic plasma concentrations of each drug, but it did not change after lidocaine treatment up to 100 μM. CT was increased by astemizol, flecainide, terfenadine, and lidocaine at equivalent concentrations of Nav1.5 IC50, suggesting that CT may be an index of cardiac depolarization because the increase in CT (i.e., decrease in cell-to-cell conduction speed) was relevant to Nav1.5 inhibition. Fluctuations (short-term variability; STV) of FPD and CT, STVFPD and STVCT also discriminated between torsadogenic and non-torsadogenic compounds with significant increases in their fluctuation values, enabling precise prediction of arrhythmogenic risk as potential new indices.

Significance of dual polarimetric synthetic aperture radar in biomass retrieval: An attempt on Sentinel-1

The study investigates the suitability of Sentinel-1 data product of C-band frequency (5.36 GHz) in the estimation of terrestrial biomass. The experiment was carried out in the Perambular District, Tamil Nadu, India. The model DPSVI (Dual Polarization SAR Vegetation Index) was proposed based on the pattern of scatter plot constructed between the backscattering coefficient of VV (σvvo) and VH (σvho) imageries in which the pixels representing the surface features such as vegetation, soil, and water bodies were distributed according to the theory ‘Degree of Depolarization (DOP)’. The model was developed by proposing and integrating three crucial parameters (i) Inverse Dual-Pol Diagonal Distance (IDPDD) (ii) Vertical Dual De-polarization Index (VDDPI) and (iii) σvho which are highly influential towards biomass extraction. The model was executed for two different seasons (wet and dry) from 2015 to 2017. The resultant output was tested with Normalized Differential Vegetation Index (NDVI) derived from Sentinel 2, and the field observed Above Ground Biomass (AGB) from 50 sampling locations to demonstrate the theoretical and in-situ potential of the proposed model. The resultant product of the DPSVI has shown the acceptable R2 value of 0.75 for the dry season and 0.73 for the wet season with NDVI and got R2 value of 0.73 for the dry and R2 value of 0.70 for the wet season with AGB which manifested that the proposed model was an effective indicator of terrestrial vegetation irrespective of seasons.

Noninvasive measurement of glucose concentration on human fingertip by optical coherence tomography.

A method is proposed for determining the glucose concentration on the human fingertip by extracting two optical parameters, namely the optical rotation angle and the depolarization index, using a Mueller optical coherence tomography technique and a genetic algorithm. The feasibility of the proposed method is demonstrated by measuring the optical rotation angle and depolarization index of aqueous glucose solutions with low and high scattering, respectively. It is shown that for both solutions, the optical rotation angle and depolarization index vary approximately linearly with the glucose concentration. As a result, the ability of the proposed method to obtain the glucose concentration by means of just two optical parameters is confirmed. The practical applicability of the proposed technique is demonstrated by measuring the optical rotation angle and depolarization index on the human fingertip of healthy volunteers under various glucose conditions.

Optical characterization of porcine articular cartilage using a polarimetry technique with differential Mueller matrix formulism.

A method is proposed for characterizing the optical properties of articular cartilage sliced from a pig's thighbone using a Stokes-Mueller polarimetry technique. The principal axis angle, phase retardance, optical rotation angle, circular diattenuation, diattenuation axis angle, linear diattenuation, and depolarization index properties of the cartilage sample are all decoupled in the proposed analytical model. Consequently, the accuracy and robustness of the extracted results are improved. The glucose concentration, collagen distribution, and scattering properties of samples from various depths of the articular cartilage are systematically explored via an inspection of the related parameters. The results show that the glucose concentration and scattering effect are both enhanced in the superficial region of the cartilage. By contrast, the collagen density increases with an increasing sample depth.

Selective sensitivity of Mueller imaging for tissue scattering over absorption changes in cancer mimicking phantoms

Tissue characterization using optical polarimetry, especially Mueller imaging is receiving sustained interest due to its potential in achieving optical contrast between normal and malignant variations. This is particularly important in identifying the margin of malignant growth in suspected tissue regions for accurate surgical removal, or in aiding the sampling procedure during biopsy. The sensitivity of Mueller matrix derived depolarization index to the combined effects of changes in scattering and absorption occurring in a cancerous growth is illustrated in this study. Depolarization imaging is shown to be useful in demarcating the boundary of two regions of differing optical properties using a tissue phantom, modeled according to the changes expected during cancerous growth in tissue. Tissue scattering and absorption are expected to generally increase with the nuclear size change and crowding as well as angiogenesis associated with malignancy. We have observed that there is selective sensitivity for the Mueller elements and derived depolarization index to tissue scattering over absorption in the object field. Although the scattering and absorption are expected to increase and decrease depolarization respectively, the optical contrast of Mueller images and the derived depolarization index between normal and cancerous tissue is found appreciable in this region.

Synthesis and characterization of depolarizing samples based on the indices of polarimetric purity.

In this work, we discuss the interest of using the indices of polarimetric purity (IPPs) as a criterion for the characterization and classification of depolarizing samples. We prove how differences in the depolarizing capability of samples, not seen by the commonly used depolarization index PΔ, are identified by the IPPs. The above-stated result is analyzed from a theoretical point of view and experimentally verified through a set of polarimetric measurements. We show how the approach presented here can be useful in easily synthetizing depolarizing samples with controlled depolarizing features, just by properly combining low-cost fully polarizing elements (such as linear retarders or polarizers).

Physically Realizable Space for the Purity-Depolarization Plane for Polarized Light Scattering Media.

We propose a physically realizable space for the polarized light scattering measurement using the Stokes-Mueller formalism by a purity-index-depolarization-index (PI-P_{Δ}) plane. The parameter PI is defined from indices of polarimetric purity (IPP), which exhibits the overall magnitude of the polarimetric randomness of a medium, while the depolarization index (P_{Δ}) delineates a proper global degree of polarimetric purity and may also refer to the average measure of depolarization power of the scattering medium. Subregions and curves connecting the edge points in the plane are obtained by imposing certain constraints on the IPP; consequently any point on the subregion indicates the information related to a decomposition of the Mueller matrix into its components as a convex sum. From the same set of constraints, complete information about the depolarization index versus the entropy [S(M)-P_{Δ}] diagram is recovered. This work provides a simple geometric representation and a deeper perceptivity of the light scattering media comprising depolarization.

Differential Mueller matrix polarimetry technique for non-invasive measurement of glucose concentration on human fingertip.

A differential Mueller matrix polarimetry technique is proposed for obtaining non-invasive (NI) measurements of the glucose concentration on the human fingertip. The feasibility of the proposed method is demonstrated by detecting the optical rotation angle and depolarization index of tissue phantom samples containing de-ionized water (DI), glucose solutions with concentrations ranging from 0~500 mg/dL and 2% lipofundin. The results show that the extracted optical rotation angle increases linearly with an increasing glucose concentration, while the depolarization index decreases. The practical applicability of the proposed method is demonstrated by measuring the optical rotation angle and depolarization index properties of the human fingertips of healthy volunteers.

Estimating Depolarization with the Jones Matrix Quality Factor

Mueller matrix (MM) measurements offer the ability to quantify the depolarization capability of a sample. Depolarization can be estimated using terms such as the depolarization index or the average degree of polarization. However, these calculations require measurement of the complete MM. We propose an alternate depolarization metric, termed the Jones matrix quality factor, QJM, which does not require the complete MM. This metric provides a measure of how close, in a least-squares sense, a Jones matrix can be found to the measured Mueller matrix. We demonstrate and compare the use of QJM to other traditional calculations of depolarization for both isotropic and anisotropic depolarizing samples; including non-uniform coatings, anisotropic crystal substrates, and beetle cuticles that exhibit both depolarization and circular diattenuation.

Optical diagnosis of dengue virus infected human blood using Mueller matrix polarimetry

Currently dengue fever diagnosis methods include capture ELISAs, immunofluorescence tests, and hemagglutination assays. In this study optical diagnosis of dengue virus infection in the whole blood is presented utilizing Mueller matrix polarimetry. Mueller matrices of about 50 dengue viral infected and 25 non-dengue healthy blood samples were recorded utilizing light source from 500 to 700 nm with scanning step of 10 nm. Polar decomposition of the Mueller matrices for all the blood samples was performed that yielded polarization properties including depolarization, diattenuation, degree of polarization, retardance and optical activity, out of which, depolarization index clusters up the diseased and healthy in to different separate groups. The average depolarized light in the case of dengue infection in the whole blood at 500 nm is 18%, whereas for the healthy blood samples it is 13.5%. This suggests that depolarization index of polarized light at the wavelengths of 500, 510, 520, 530 and 540 nm, we find that in case of depolarization index values are higher for dengue viral infection as compared to normal samples. This technique can effectively be used for the characterization of the dengue virus infected at an early stage of disease.

Enhanced depolarization contrast in polarization-sensitive optical coherence tomography.

We demonstrate the first application of the differential depolarization index (DDI) for depolarization imaging in polarization-sensitive optical coherence tomography (PS-OCT). Unlike the widely used degree of polarization uniformity (DOPU), the DDI is independent of the incident polarization state and, therefore, more robust to varying system and sample parameters. Moreover, it can be applied to single-input-polarization-state PS-OCT systems, and it overcomes several limitations of the emerging depolarization index used in multiple-input-polarization-state systems. Our results on tissue phantoms and human skin prove that DDI yields significant depolarization contrast improvements compared to DOPU, which highlights its potential for depolarization imaging in PS-OCT.

Characterization of natural and irradiated nails by means of the depolarization metrics.

Mueller polarimetry is applied to study the samples of nails: natural (or reference) and irradiated to 2 Gy ionizing radiation dose. We measure the whole Mueller matrices of the samples as a function of the scattering angle at a wavelength of 632.8 nm. We apply depolarization analysis to measured Mueller matrices by calculating the depolarization metrics [depolarization index, Q(M)-metric, first and second Lorenz indices, Cloude and Lorenz entropy] to quantify separability of the different samples of nails under study based on differences in their Mueller matrix. The results show that nail samples strongly depolarize the output light in backscattering, and irradiation in all cases results in increasing of depolarization. Most sensitive among depolarization metrics are the Lorenz entropy and Q(M)-metric.

Noninvasive optical diagnostic of breast cancer using depolarization of light

Abstract In this study we implemented depolarization on whole blood samples of 20 adult breast cancer patients as well as 20 normal healthy persons and recorded Mueller matrix based polarization parameters. The most useful polarization parameter on the basis of which we can distinguish the breast cancer disease from normal is depolarization index. We have used a wavelength range of light from 400 to 800 nm wavelength at a fixed transmission window of 0.18 - 0.19 for all the samples. In case of Breast cancer 90% – 70% light is depolarized in the spectral range of 420 – 480 nm. For normal blood less light is depolarized i.e., 78% – 55%. For second spectral range 500 – 560 nm measure depolarization index is 23% – 20% for breast cancer but 15% – 14% for normal blood. Similarly, other polarization parameters like linear retardence, circular retardence, and linear diattenuation for breast cancer differ from normal blood samples.

Depolarization index for dielectric aging indicator of rotating machines

The term Depolarization Index (dP.I.) for rotating machines is introduced in this article as an additional information to the time-domain and frequency-domain dielectric response results for gaining high-precision interpretation and identification of some types of aging in solid dielectrics, particularly the non-restoring thermal trouble and insulation abrasion. Factors affecting the correctness and accuracy of dP.I. are discussed. The dP.I data from 60 medium-to-large generators and 117 large industrial motors, in Asia-Pacific were analyzed to provide the conclusion.

Polarimetric Characterization of Unresolved Space Objects

This paper introduces a new remote sensing technique based on polarimetric detection principles, aimed at enhancing the identification, characterization, and discrimination of unresolved space objects like amorphous silicon, polysilicon, Mylar, and Kapton. Some of the polarimetric measurements performed at different angles of incidence (object angular rotations) such as diattenuation, depolarization and retardance matrices of these space objects are presented using backscattered polarimetric signals obtained with a polarimetric system (test bed). The depolarization index profile with changing angle of incidence for these samples is approximated by an inverted Gaussian function. Depolarization is minimum for specular reflection and increases asymptotically in a Gaussian fashion as the angles of incidence and scatter increase. Parameters of the Gaussian profiles fitted to the depolarization data are used to compare samples. The results show that the shape of depolarization profile for one object (Mylar) is almost flat, whereas the other three objects (amorphous silicon, polysilicon, and Kapton) show depolarizing trend with increasing angle of incidence. Additionally, the fractal properties of these objects using the backscattered polarimetric signals obtained with the polarimetric system is compared. The fractal dimension of the backscattered polarimetric signals is obtained for two different experimental geometries, copolarized and cross-polarized geometry, for two different object angular rotations using multiresolution box-counting technique. The results confirms that the fractal dimension of the cross-polarized signals are greater than that for copolarized signals of all objects and increases as the angular rotation of the object increases.