Imaging polarimetry has emerged over the past three decades as a powerful tool to enhance the information available in a variety of remote sensing applications. We discuss the foundations of passive imaging polarimetry, the phenomenological reasons for designing a polarimetric sensor, and the primary architectures that have been exploited for developing imaging polarimeters. Considerations on imaging polarimeters such as calibration, optimization, and error performance are also discussed. We review many important sources and examples from the scientific literature.

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Review of passive imaging polarimetry for remote sensing applications

This paper reviews the state of the art of optical coherence tomography (OCT), an interferometric imaging technique that provides cross-sectional views of the subsurface microstructure of biological tissue. Following a discussion of the basic theory of OCT, an overview of the issues involved in the design of the main components of OCT systems is presented. The review concludes by introducing new imaging modes being developed to extract additional diagnostic information.

Optical coherence tomography (OCT): a review

The authors present two figures of merit based on singular value decomposition which can be used to assess the noise immunity of a complete Stokes polarimeter. These are used to optimize a polarimeter consisting of a rotatable retarder and fixed polarizer. A retardance of 132{degree} (approximately three eights wave) and retarder orientation angles of {+-}51.7{degree} and {+-}15.1{degree} are found to be optimal when four measurements are used. Use of this retardance affords a factor of 1.5 improvement in signal-to-noise ratio over systems employing a quarter wave plate. A geometric means of visualizing the optimization process is discussed, and the advantages of the use of additional measurements are investigated. No advantage of using retarder orientation angles spaced uniformly through 360{degree} is found over repeated measurements made at the four angles given previously.

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Optimization of retardance for a complete Stokes polarimeter.

The use of the Monte Carlo method in radiative heat transfer is reviewed. The review covers surface-surface, enclosure, and participating media problems. Discussio. is included of research on the fundamentals of the method and on applications to surface-surface interchange in enclosures, exchange between surfaces with roughness characteristics, determination of configuration factors, inverse design, transfer through packed beds and fiber layers, participating media, scattering, hybrid methods, spectrally dependent problems including media with line structure, effects of using parallel algorithms, practical applications, and extensions of the method. Conclusions are presented on needed future work and the place of Monte Carlo techniques in radiative heat transfer computations

The Monte Carlo Method in Radiative Heat Transfer

Three Monte Carlo programs were developed which keep track of the status of polarization of light traveling through mono-disperse solutions of micro-spheres. These programs were described in detail in our previous article [1]. This paper illustrates a series of Monte Carlo simulations that model common experiments of light transmission and reflection of scattering media. Furthermore the codes were expanded to model light propagating through poly-disperse solutions of micro-spheres of different radii distributions.

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Three Monte Carlo programs of polarized light transport into scattering media: part II.

The four optimum rotation angles for a polarimeter consisting of a quarter-wave plate in conjunction with a linear polarizer are found. This is done by using the determinant and condition numbers of the system measurement matrix as objective functions in a minimization procedure. The four angles so found result in the polarimeter's estimate of the incident Stokes vector to have a minimum sensitivity with respect to fluctuations in the detected flux and errors in the angular position of the optical components constituting the polarimeter. Four optimal angles are presented. These four angles also retain a simplicity of form for the measurement matrix.

Optimum Angles for a Polarimeter: Part II

A backward Monte Carlo estimator is developed to describe the multiple scattering of a polarized, narrow light beam by a plane-parallel medium. The case of a right circularly polarized beam is analyzed in this paper. Results indicate that the diffuse light field is partially polarized even at significant optical radii from the incident light beam. The degree of polarization of the diffuse light field is dependent on the optical thickness of the medium and the size parameter of the scatterers.

A backward Monte Carlo study of the multiple scattering of a polarized laser beam

A backward Monte Carlo estimator is derived for the multiple scattering of a narrow light beam of arbitrary spatial distribution incident on a plane parallel layer. A means of obtaining an error estimate which provides an upper bound on the actual error is suggested. The intuitively clear result that the higher order intensities asymptotically approach each other for all optical radii was observed. It is observed that at reasonably modest optical distances from the beam, consideration of only the first or second orders of scatter in the evaluation of the diffuse light field will lead to erroneous results.

A backward Monte Carlo estimator for the multiple scattering of a narrow light beam

The four optimum rotation angles for a Mueller matrix polarimeter consisting of a quarter wave plate in conjunction with a linear polarizer, are found. This is done by using the determinant and condition numbers of the system measurement matrix as objective functions in a minimization procedure. The four angles so found result in the polarimeter's estimate of the incident Stokes vector to have a minimum sensitivity with respect to fluctuations in the detected flux and errors in the angular position of the optical components constituting the polarimeter. Four optimal angles are presented. These four angles also retain a simplicity of form for the measurement matrix.

Optimum Angles for a Mueller Matrix Polarimeter

In this paper the forward-scattered diffuse radiation produced by a circularly polarized laser beam impinging on a e nite plane-parallel scattering medium is studied experimentally. The radial variation of the forward-scattered Stokes vector is analyzed. Values of the degree of circular and linear polarization of the scattered radiation computed using experimental data are compared with values obtained using a Monte Carlo code. Trends with respect to the size parameters of the scatterers and the optical thickness are also presented. It was observed that the diffuse radiation is strongly polarized, even at large optical radii. This is true for all the size parameters and optical depths of the medium studied.

Amrit Ambirajan

Papers

Optimum Angles for a Polarimeter: Part II

A backward Monte Carlo study of the multiple scattering of a polarized laser beam

A backward Monte Carlo estimator for the multiple scattering of a narrow light beam

Optimum Angles for a Mueller Matrix Polarimeter

Experimental Investigation of the Multiple Scattering of a Polarized Laser Beam