J. J. Gil

Bio: J. J. Gil is an academic researcher from University of Zaragoza. The author has contributed to research in topics: Optical polarization. The author has an hindex of 1, co-authored 1 publications receiving 218 citations.

Polarimetric characterization of light and media - Physical quantities involved in polarimetric phenomena

Abstract: An objective analysis is carried out of the matricial models representing the polarimetric properties of light and material media leading to the identification and definition of their corresponding physical quantities, using the concept of the coherency matrix. For light, cases of homogeneous and inhomogeneous wavefront are analyzed, and a model for 3D polarimetric purity is constructed. For linear passive material media, a general model is developed on the basis that any physically realizable linear transformation of Stokes vectors is equivalent to an ensemble average of passive, deterministic nondepolarizing transformations. Through this framework, the relevant physical quantities, including indices of polarimetric purity, are identified and decoupled. Some decompositions of the whole system into a set of well-defined components are considered, as well as techniques for isolating the unknown components by means of new procedures for subtracting coherency matrices. These results and methods constitute a powerful tool for analyzing and exploiting experimental and industrial polarimetry. Some particular application examples are indicated.

Stokes-vector and Mueller-matrix polarimetry [Invited].

Abstract: This paper reviews the current status of instruments for measuring the full 4×1 Stokes vector S, which describes the state of polarization (SOP) of totally or partially polarized light, and the 4×4 Mueller matrix M, which determines how the SOP is transformed as light interacts with a material sample or an optical element or system. The principle of operation of each instrument is briefly explained by using the Stokes-Mueller calculus. The development of fast, automated, imaging, and spectroscopic instruments over the last 50 years has greatly expanded the range of applications of optical polarimetry and ellipsometry in almost every branch of science and technology. Current challenges and future directions of this important branch of optics are also discussed.

SAR polarimetry for sea oil slick observation

Abstract: In this article, a review of polarimetric synthetic aperture radar SAR methods for sea oil slick observation is presented. Marine oil pollution monitoring is a topic of great applicative and scientific relevance. In this framework, the use of remotely sensed measurements is of special interest and, in particular, the SAR because of its almost all-weather and all-day imaging capability at fine spatial resolution is the most effective tool. Conventional single-polarization SAR oil spill monitoring techniques are limited in their capability to detect oil slicks since they strongly rely on suitable thresholds, training samples, and ancillary information. Hence, an expert image analyst is due. The launch of a number of polarimetric SAR missions, along with the understanding of the peculiar physical mechanisms governing the scattering by an oil slick, led to a new paradigm known as physical processing that fostered a set of polarimetric algorithms particularly robust and efficient. Hence, suitable polarimetric models that exploit the departure from the slick-free sea Bragg scattering have been developed to effectively address oil slick monitoring. A set of polarimetric features extracted following such electromagnetic models have been proved to be reliable for oil slick monitoring. Polarimetric SAR observations led to a significant improvement in sea oil slick observation since they allow distinguishing oil slicks from a broad class of lookalikes in an unsupervised way. In addition, deeper information on the damping properties of the pollutant can be also inferred, which is of paramount importance for remediation purposes. Such physical processing has been demonstrated to be robust at variance of microwave carrier frequency, e.g. L-, C-, and X-band, and suitable to be exploited to extract information by dual-polarized, full-polarized, and compact modes. All these make such a physical approach of operational interest since it is able to exploit a larger set of SAR measurements building up a virtual constellation. In this review all these are detailed.

Mueller Matrix Polarimetry—An Emerging New Tool for Characterizing the Microstructural Feature of Complex Biological Specimen

Abstract: Recently, with the emergence of new light sources, polarization devices, and detectors, together with a prominent increase in data processing capability, polarization techniques find more and more applications in various areas, one of which is biomedicine. For probing the characteristic features of complex biomedical specimen, Mueller matrix polarimetry has demonstrated distinctive advantages. Mueller matrix polarimetry can be achieved on other optical techniques by adding the polarization state generator and analyzer to their existing optical paths appropriately. Common biomedical optical equipment, such as microscopes and endoscopes, can be upgraded to fulfill Mueller matrix imaging and measurement abilities. Compared with traditional non-polarization optical methods, Mueller matrix polarimetry can provide far more information to characterize the samples, including the anisotropic optical properties, such as birefringence and diattenuation, as well as the distinctive features of various scattering particles and microstructures. Also, Mueller matrix polarimetry is more sensitive to scattering by sub-wavelength microstructures. As a label-free and non-invasive tool, Mueller matrix polarimetry has broad application prospects in biomedical studies and clinical diagnosis. In this review, we provide an introduction to the Mueller matrix methodology, including the Stokes–Mueller formalism, and also the decomposition and transformation methods to derive new parameters. We also summarize the status of the Mueller matrix polarimetric field, including recent improvements, both in instrumentation and data analysis. The current and future applications of Mueller matrix polarimetry in biomedicine are provided and discussed.