This PDF file contains the front matter associated with SPIE Proceedings Volume 9613, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

We report the experimental validation of a snapshot computational degree of polarization imaging technique, based on local analysis of the statistics of a single speckle image acquisition. The applicability of this imaging technique is demonstrated on various samples, and it precision is analyzed and compared with theoretical predictions. Then, we theoretically study the ability of this approach to discriminate samples with various depolarization degrees while sharing similar reflectance properties. We quantitatively compare the detection performances of this approach with standard with standard polarization imaging strategies and evaluate the increase in spatial resolution required to share similar detection efficiency.

A novel technique is proposed to unambiguously determine the magnitude and orientation of linear dichroism. It relies on the use of a dual-frequency dual-polarization coherent source emitting two orthogonal circularly polarized modes at the output. The interaction of such beam with dichroic media is shown to give rise to a beatnote signal in the radiofrequency range. The amplitude and phase of such beatnote makes it possible to fully determine the magnitude and orientation angle of the diattenuation. We also report the application of this method to polarimetric imaging, with promising perspectives in biomedical imaging. Indeed, it provides a direct characterization of dichroic sample orientation, showing uniform estimated dichroism magnitude, whatever the orientation of the sample.

Uncorrected or poorly corrected bad pixels reduce the effectiveness of polarimetric clutter suppression. In conventional microgrid processing, bad pixel correction is accomplished as a separate step from Stokes image reconstruction. Here, these two steps are combined to speed processing and provide better estimates of the entire image, including missing samples. A variation on the bilateral filter enables both edge preservation in the Stokes imagery and bad pixel suppression. Understanding the newly presented filter requires two key insights. First, the adaptive nature of the bilateral filter is extended to correct for bad pixels by simply incorporating a bad pixel mask. Second, the bilateral filter for Stokes estimation is the sum of the normalized bilateral filters for estimating each analyzer channel individually. This paper describes the new approach and compares it to our legacy method using simulated imagery.

Recently we designed and built a portable imaging polarimeter for remote sensing applications.¹ Polarimetric imaging operators are a class of linear systems operators in the Mueller matrix reconstruction space, resulting in a set of measurement channels.² The nature of remote sensing requires channel crosstalk to be minimized for either general Mueller matrix reconstruction or task specific polarimetric remote sensing. We illustrate crosstalk issues for a spatio-temporally modulated Mueller matrix reconstruction operator, and show how to minimize channel crosstalk by maximizing bandwidth between channels. Specifically channel cancellation allows increases in channel bandwidth. We also address the impact that systematic deviations from the ideal operators and i.i.d. noise have on the system channel structure.

A movable pixelated filter array is proposed to provide low cost, on demand polarimetry and wavefront sensing. With this concept, an optical system can turn polarimetry on and off by using a shutter to move a microgrid polarizer array in and out of the optical path of the system. This allows an optical system to operate in two modes, a non-polarimetric mode in which sensor range is maintained, and a polarimetric mode in which it is reduced. In implementing this concept, adequate knowledge of the position of the filter in the optical path and calibration procedures become critical topics. This paper discusses simulated and hardware-tested results of this invention.

Measuring the 2 dimensional Stokes vector, to determine the polarization state of light, finds application in multiple areas, including the characterization of aerosol size distributions, target identification, quality control by evaluating the distribution of stress birefringence, resolving data channels in telecommunications, and for evaluating biological tissues in medical imaging. Conventional methods, such as channeled and division of focal plane polarimeters, usually limit spatial resolution, while others, like division of aperture or division of amplitude polarimeters, have higher complexity and less compactness. To help solve these issues, we have developed a system that uses semitransparent organic photovoltaics (OPVs) as photodetectors. The active area of the devices consist of biaxially oriented polymer films, which enables the device to preferentially absorb certain polarized states of incident light, depending on the orientation of the polymer chains. Taking advantage of the cells’ transparency and ease of processing, compared to inorganic materials, enables multiple devices to be “stacked” along the optical axis. Presently, experiments have been conducted to detect linear polarization states of light. We use three stacked OPVs, where each device can measure one of the first three Stokes parameters simultaneously, thereby ensuring high spatial and temporal resolution with inherent spatial registration. In this paper, the fabrication of the OPVs and the design and calibration technique is documented, along with experimental data, supporting the hypothesis.

Polarimetry is a common technique used in chemistry for solution characterization and analysis, giving insight into the molecular structure of a solution measured through the rotation of linearly polarized light. This rotation is characterized by the Boits law. Without large optical path lengths, or high concentrations of solution, these optical rotations are typically very small, requiring elaborate and costly apparatuses. To ensure that the rotation measurements are accurate, these devices usually perform complex optical procedures or time-averaged point measurements to ensure that any intensity variation seen is a product of optical rotation and not from inherent noise sources in the system, such as sensor or shot noise. Time averaging is a lengthy process and rarely utilizes all of the information available on the sensor. To this end, we have developed a novel integrated, miniature, computational imaging system that enhances polarimetric measurements by taking advantage of the full spot size observed on an array detector. This computational imaging system is capable of using a single acquisition at unity gain to enhance the polarimetric measurements using a probabilistic framework, which accounts for inherent noise and optical characteristics in the acquisition process, to take advantage of spatial intensity relations. This approach is faster than time-averaging methods and can better account for any measurement uncertainties. In preliminary experiments, this system has produced comparably consistent measurements across multiple trials with the same chemical solution than time averaging techniques.

Early diagnosis of glaucoma, which is a leading cause for visual impairment, is critical for successful treatment. It has been shown that Imaging polarimetry has advantages in early detection of structural changes in the retina. Here, we theoretically and experimentally present a snapshot Mueller Matrix Polarimeter fundus camera, which has the potential to record the polarization-altering characteristics of retina with a single snapshot. It is made by incorporating polarization gratings into a fundus camera design. Complete Mueller Matrix data sets can be obtained by analyzing the polarization fringes projected onto the image plane. In this paper, we describe the experimental implementation of the snapshot retinal imaging Mueller matrix polarimeter (SRIMMP), highlight issues related to calibration, and provide preliminary images acquired from the camera.

We report on the development of a prototype polarization tag based system for detecting chemical vapors. The system primarily consists of two components, a chemically sensitive tag that experiences a change in its optical polarization properties when exposed to a specific chemical of interest, and an optical imaging polarimeter that is used to measure the polarization properties of the tags. Although the system concept could be extended to other chemicals, for the initial system prototype presented here the tags were developed to be sensitive to hydrogen fluoride (HF) vapors. HF is used in many industrial processes but is highly toxic and thus monitoring for its presence and concentration is often of interest for personnel and environmental safety. The tags are periodic multilayer structures that are produced using standard photolithographic processes. The polarimetric imager has been designed to measure the degree of linear polarization reflected from the tags in the short wave infrared. By monitoring the change in the reflected polarization signature from the tags, the polarimeter can be used to determine if the tag was exposed to HF gas. In this paper, a review of the system development effort and preliminary test results are presented and discussed, as well as our plan for future work.

Developing an efficient and robust polarimeter for wide spectral ranges and space applications is a main issue in many projects. As part of the UVMag consortium created to develop UV facilities in space (e.g. the Arago mission proposed to ESA), we are studying an innovative concept of polarimeter that is robust, simple, and efficient on a wide spectral range. The idea, based on the article by Sparks et al. (2012), is to use polarization scramblers to create a spatial modulation of the polarization. Along the height of the wedges of the scramblers, the thickness of the birefringent material crossed by the light, and thus the retardance, vary continuously. This variation creates an intensity modulation of the light related to the entrance polarization state. Analyzing this modulation with a linear polarizer, and dispersing the light spectrally in the orthogonal spatial direction, enables the measurement of the full Stokes vector over the entire spectrum. This determination is performed with a single-shot measurement and without any moving parts in the system.

After a quick introduction to the concept and optical design, this article presents the tolerancing study of the optical bench using this spectropolarimeter. The impact of different error sources, such as, birefringence uncertainty or decenter of the wedges, is investigated.

A novel spectroscopic Mueller-matrix polarimeter based on channeled spectropolarimetry is presented. It incorporates two high-order retarders and two Savart plates so that a spectrum modulated in both spatial and spectral axes are obtained from a two-dimensional CCD attached to a spectrometer. Two-dimensional Fourier analysis of the spectrum allows us to demodulate wavenumber-resolved Mueller matrix of the sample. The polarimeter uses no mechanical or active elements for polarization modulation and the snapshot measurement of sixteen Mueller-matrix elements can be achieved. Its feasibility was experimentally demonstrated in the spectral range between 500 and 750 nm.

We present the design and prototyping results for an ultra-wideband rotating polarization modulator that consists of a stack of quartz plates. The plate thicknesses and orientations were optimized such that after rotation of the modulator to 6 different angles before a polarization analyzer, the full Stokes vector can be optimally determined at all wavelengths from 300 to 2500 nm. Additional optimization parameters include minimal variation of the retardance with incidence angle and temperature, and the suppression of polarized spectral fringes for a spectral resolution of 10,000. The prototype modulator's design was re-optimized after the production and measurement of each individual quartz plate. We present the performance of the as-built prototype. To eliminate aliasing with inherent temporal variations of the source, the modulator can be used together with a polarizing beam-splitter (dual-beam" approach). Because of the large sinusoidal spectral variations of the polarization modulation, this modulator can also be considered a "spectral modulator for channeled spectropolarimetry". Therefore, at each modulation state, spectrally resolved polarization information can also be extracted directly, although at limited spectral resolution. We use this modulator as an example of a "multi-domain polarization modulator", and outline a general approach for optimally storing polarization information in all available measurement dimensions (temporal, spatial, spectral), and rendering the overall polarization measurement independent from systematic effects in any of these dimensions.

The point spread function (PSF) for astronomical telescopes and instruments depends not only on geometric aberrations and scalar wave diffraction, but also on the apodization and wavefront errors introduced by coatings on reflecting and transmitting surfaces within the optical system. The functional form of these aberrations, called polarization aberrations, result from the angles of incidence and the variations of the coatings as a function of angle. These coatings induce small modifications to the PSF, which consists of four separate components, two nearly Airy-disk PSF components, and two faint components, we call ghost PSF components, with a spatial extent about twice the size of the diffraction limited image. As the specifications of optical systems constantly improve, these small effects become increasingly important. It is shown how the magnitude of these ghost PSF components, at ~10^-5 in the example telescope, can interfere with exoplanet detection with coronagraphs.

A polarization modulator based on Liquid Crystal Variable Retarders (LCVRs) will be used in the Polarimetric and Helioseismic Imager (PHI) for the Solar Orbiter mission to measure the complete Stokes vector of the incoming light. PHI is one of the six remote sensing instruments onboard of this space mission led by the European Space Agency (ESA) with strong NASA participation. It is an imaging spectro-polarimeter that will acquire high resolution solar magnetograms. Also the LCVRs will be used in the polarization modulator of the METIS instrument (Multi Element Telescope for Imaging and Spectroscopy). METIS is a solar coronagraph that will analyze the linear polarization for observations of the visible-light K-corona.

The polarization modulators are described in this work including the optical, mechanical, thermal and electrical aspects. Both modulators will consist of two identical LCVRs with a relative azimuth orientation of 45º for PHI and parallel for the METIS modulator. In the first case, the configuration allows the analysis of the full Stokes vector with maximum polarimetric efficiencies. In the second setup, wide acceptance angles (≤ ±7°) are obtained.

This works presents the preliminary results obtained for the full representative prototypes from the verification and environmental test campaign in progress currently. The main performances were measured and analyzed including polarimetric efficiencies, wavefront error transmission, beam deviation and transmittance. This valuable information will allow to consolidate the detailed design of these devices increasing its TRL to 6 and to proceed to the manufacturing of the Qualification Model (QM) and Flight Models (FM).

An optical design program, Polaris-M, developed at the University of Arizona incorporates many advanced polarization analysis features. At the core of the program is a three-dimensional polarization ray tracing structure used to characterize polarization effects occurring at interfaces and upon propagation through isotropic and anisotropic materials. Reflection and refraction at uniaxial, biaxial, and optically active interfaces are handled rigorously, as well as anisotropic grating structures. By analyzing multiple polarized wavefront components individually, one can study the complicated effects of multiple anisotropic optical elements at the image. Wavefronts can be expanded into polarization aberration terms. Polarized diffraction image formation and polarization dependent optical transfer functions are included.

In contrast to the National Oceanic and Atmospheric Administration’s (NOAA’s) current geostationary imagers for operational weather forecasting, the next generation imager, the Advanced Baseline Imager (ABI) aboard the Geostationary Operational Environmental Satellite R-Series (GOES-R), will have six reflective solar bands - five more than currently available. These bands will be used for applications such as aerosol retrievals, which are influenced by polarization effects. These effects are determined by two factors: instrument polarization sensitivity and the polarization states of the observations. The former is measured as part of the pre-launch testing program performed by the instrument vendor. We analyzed the results of the pre-launch polarization sensitivity measurements of the 0.47 μm and 0.64 μm channels and used them in conjunction with simulated scene polarization states to estimate potential on-orbit radiometric impacts. The pre-launch test setups involved illuminating the ABI with an integrating sphere through either one or two polarizers. The measurement with one (rotating) polarizer yields the degree of linear polarization of ABI, and the measurements using two polarizers (one rotating and one fixed) characterized the non-ideal properties of the polarizer. To estimate the radiometric performance impacts from the instrument polarization sensitivity, we simulated polarized scenes using a radiative transfer code and accounted for the instrument polarization sensitivity over its field of regard. The results show the variation in the polarization impacts over the day and by regions of the full disk can reach up to 3.2% for the 0.47μm channel and 4.8% for the 0.64μm channel. Geostationary orbiters like the ABI give the unique opportunity to show these impacts throughout the day compared to low earth orbiters, which are more limited to certain times of day. This work may enhance the ability to diagnose anomalies on-orbit.

Diffractive retarders fabricated from gratings in isotropic materials are analyzed by rigorous coupled wave analysis. Calculations show it is difficult to obtain substantial retardance with isotropic phase gratings. Even for an aspect ratio of two, diffractive retarders have a small retardance, < λ/12. Thus it is generally impractical to fabricate quarter wave retarders, much less half wave retarders in plastic or molded glass for example. The dispersion of these gratings is compared to the conventional materials used in the majority of retarders and is found to be very similar. Thus these gratings add little in terms of helping to achromatize retarders

In prior work,^1,2 we introduced methods to treat channeled systems in a way that is similar to Data Reduction Method (DRM), by focusing attention on the Fourier content of the measurement conditions. Introduction of Q enabled us to more readily extract the performance of the system and thereby optimize it to obtain reconstruction with the least noise. The analysis tools developed for that exercise can be expanded to be applicable to partial Mueller Matrix Polarimeters (pMMPs), which were a topic of prior discussion as well. In this treatment, we combine the principles involved in both of those research trajectories and identify a set of channeled pMMP families. As a result, the measurement structure of such systems is completely known and the design of a channeled pMMP intended for any given task becomes a search over a finite set of possibilities, with the additional channel rotation allowing for a more desirable Mueller element mixing.

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, di-attenuation 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.

Polarimeters operate by making polarization-dependent alterations in the intensity of the optical field. Modulated polarimeters introduce controlled fluctuations as a function of time, spatial position, wavelength, angle of incidence, or any other independent variable. These fluctuations create channels in frequency space that can be used to carry the polarimetric information. Since polarimeters are then inherently multiplexed information systems, issues of noise, bandwidth, channel cross-talk, and system conditioning become immediately important. This paper reviews much of the work over the past two decades on polarimeter design, and presents some of the most recent work on hybrid and non-periodic modulation schemes that hold out potential for maximizing system bandwidth.

Knowledge of the polarization state of natural skylight is important to growing applications using polarimetric sensing. We previously published measurements and simulations illustrating the complex interaction between atmospheric and surface properties in determining the spectrum of skylight polarization from the visible to near-infrared (1 μm).¹ Those results showed that skylight polarization can trend upward or downward, or even have unusual spectral discontinuities that arise because of sharp features in the underlying surface reflectance. The specific spectrum observed in a given case depended strongly on atmospheric and surface properties that varied with wavelength. In the previous study, the model was fed with actual measurements of highly variable aerosol and surface properties from locations around the world. Results, however, were limited to wavelengths below 1 μm from a lack in available satellite surface reflectance data at longer wavelengths. We now report measurement-driven simulations of skylight polarization from 350 nm to 2500 nm in the short-wave infrared (SWIR) using hand-held spectrometer measurements of spectral surface reflectance. The SWIR degree of linear polarization was found to be highly dependent on the aerosol size distribution and on the resulting relationship between the aerosol and Rayleigh optical depths. Unique polarization features in the modeled results were attributed to the surface reflectance and the skylight DoLP generally decreased as surface reflectance increased.

We introduce an algorithm based on morphological filters with the Stokes parameters that augments the daytime and nighttime detection of weak-signal manmade objects immersed in a predominant natural background scene. The approach features a tailored sequence of signal-enhancing filters, consisting of core morphological operators (dilation, erosion) and higher level morphological operations (e.g., spatial gradient, opening, closing) to achieve a desired overarching goal. Using representative data from the SPICE database, the results show that the approach was able to automatically and persistently detect with a high confidence level the presence of three mobile military howitzer surrogates (targets) in natural clutter.

Highly accurate multi-angle polarimeters are essential for taking the next step in global characterization of atmospheric aerosol. Spectral polarization modulation enables highly accurate snapshot polarimetry and is very suitable for ground-, air- and space-based instrumentation. In this paper we present two instruments that employ this technology, the SPEX prototype and groundSPEX. We have performed ground-based measurements at the CESAR Observatory in the Netherlands with these two instruments. We compare the measured degree of linear polarization of co-located measurements, which show an rms difference of 0.005. Aerosol microphysical properties that have been retrieved from these measurements agree well with similar retrievals from AERONET measurements. Finally, we discuss the current efforts to upgrade the SPEX prototype to an autonomous instrument suitable for flying on NASA’s ER-2 high altitude aircraft.

Representative examples from three-years of measurements from JPL's Ground-based Multiangle SpectroPolarimetric Imager (Ground-MSPI)[1] are compared to a model for the surface polarized bidirectional reflectance distribution matrix (BRDM). Ground-MSPI is an eight-band spectropolarimetric camera mounted on a rotating gimbal to acquire push-broom imagery of outdoor landscapes. The camera uses a photoelastic-modulator-based polarimetric imaging technique to measure linear Stokes parameters in three wavebands (470, 660, and 865 nm) with a ±0.005 uncertainty in degree of linear polarization (DoLP). Comparisons between MSPI measurements, BRDM models, and common modifications to the model are made over a range of scattering angles determined from a fixed viewing geometry and varying sun positions over time. The BRDM model is comprised of a volumetric reflection term plus a specular reflection term of Fresnel-reflecting micro-facets. We consider modifications to this model using a shadowing function and two different micro-facet scattering density functions. We report the root-mean-square error (RMSE) between the Ground-MSPI measurements and BRDM model. The BRDM model predicts an angle of the linear polarization (AoLP) that is perpendicular to the scattering plane. This is usually, but not always, observed in Ground-MSPI measurements and in this work we offer explanations for some of the deviations from the model.

Many models used to represent the boundary condition for the separation of atmospheric scattering from the surface reflectance in polarized remote sensing measurements assume that the polarized surface reflectance is spectrally neutral. The Spectral Invariance Hypothesis asserts that the magnitude and shape of the polarized bidirectional reflectance factor (pBRF) is equal for all wavelengths. In order to test this hypothesis, JPL's Ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI) is used to measure polarization information of different outdoor surface types. GroundMSPI measures the linear polarization Stokes parameters (I, Q, U), at three wavelengths, 470 nm, 660 nm, and 865 nm. The camera is mounted on a two-axis gimbal to accurately select the view azimuth and elevation directions. On clear sky days we acquired day-long scans of scenes that contain various surface types such as grass, dirt, cement, brick, and asphalt and placed a Spectralon panel in the camera field of view to provide a reflectance reference. Over the course of each day, changing solar position in the sky provides a large range of scattering angles for this study. The polarized bidirectional reflectance factor (pBRF) is measured for the three wavelengths and the best fit slope of the spectral correlation is reported. This work reports the range of best fit slopes measured for five region types.

Optimally enhanced vision of a polarized lightmark in obscured weather conditions (fog, haze, cloud) is reported when imaged over long distances (above 1 km) using a snapshot polarimetric camera. We derive and experimentally validate an optimal adaptive polarimetric representation, whose expression is shown to depend on the correlation of the noise fluctuations in the two orthogonal polarimetric images. We quantitatively compare the gain (experimental and theoretical) in contrast with respect to standard intensity imaging, and standard polarimetric representations. Lastly, we discuss efficient implementation strategies for automated detection in real-time in obscured weather conditions.

During two cruises in 2014, the polarized radiance of the ocean and the sky were continuously acquired using a HyperSAS-POL system. The system consists of seven hyperspectral radiometric sensors, three of which (one unpolarized and two polarized) look at the water and similarly three at the sky. The system autonomously tracks the Sun position and the heading of the research vessel to which it is attached in order to maintain a fixed relative azimuth angle with respect to the Sun (i.e. 90°) and therefore avoid the specular reflection of the sunlight. For the duration of both cruises, (NASA Ship Aircraft Bio-Optical Research (SABOR), and NOAA VIIRS Validation/Calibration), in situ inherent optical properties (IOPs) were continuously acquired using a set of instrument packages modified for underway measurement, and hyperspectral radiometric measurements were taken manually at all stations. During SABOR, an underwater polarimeter was deployed when conditions permitted. All measurements were combined in an effort to first develop a glint (sky + Sun) correction scheme for the upwelling polarized signal from a wind driven ocean surface and compare with one assuming that the ocean surface is flat.

Polarimetric hyperspectral imaging (P-HSI) combines two of the most common remote sensing modalities. This work leverages the combination of these techniques to improve material classification. Classifying and identifying materials requires parameters which are invariant to changing viewing conditions, and most often a material’s reflectivity or emissivity is used. Measuring these most often requires assumptions be made about the material and atmospheric conditions. Combining both polarimetric and hyperspectral imaging, we propose a method to remotely estimate the index of refraction of a material. In general, this is an underdetermined problem because both the real and imaginary components of index of refraction are unknown at every spectral point. By modeling the spectral variation of the index of refraction using a few parameters, however, the problem can be made overdetermined. A number of different functions can be used to describe this spectral variation, and some are discussed here. Reducing the number of spectral parameters to fit allows us to add parameters which estimate atmospheric downwelling radiance and transmittance. Additionally, the object temperature is added as a fit parameter. The set of these parameters that best replicate the measured data is then found using a bounded Nelder-Mead simplex search algorithm. Other search algorithms are also examined and discussed. Results show that this technique has promise but also some limitations, which are the subject of ongoing work.

Optical polarimetry is an approach that shows promise for refractive index estimation from scattering off a target’s surface, which is task of pivotal importance for remote sensing and computer graphics applications. However, the estimation often relies on a microfacet polarimetric bidirectional reflectance distribution function (pBRDF) that is limited to specular targets involving single surface scattering. In this paper, we develop an analytic model for the degree of polarization (DOP) reflected from a rough surface that includes a multiplicative factor for the effect of diffuse scattering. Evaluation of the model indicates that diffuse scattering can significantly affect the DOP values, and the biased DOP values can further lead to inaccurate estimation of the surface refractive index.

In remote sensing, the Photochemical Reflectance Index (PRI) provides insight into physiological processes occurring inside leaves in a plant stand. Developed by^1,2, PRI evolved from laboratory reflectance measurements of individual leaves. Yet in a remotely sensed image, a pixel measurement may include light from both reflecting and transmitting leaves.

We compared values of PRI based upon polarized reflectance and transmittance measurements of water and nutrient stressed leaves. Our results show the polarized leaf surface reflection should be removed when calculating PRI and that the leaf physiology information is in leaf interior reflectance, not leaf transmittance.

The Multi-Viewing-Channel-Polarisation Imager (3MI), planned to fly on the EPS-SG platform in the time-frame 2020–2040, is a 2D wide field of view radiometer dedicated to aerosol and cloud characterisation for climate monitoring, atmospheric composition, air quality and numerical weather prediction. The role of clouds in determining climate sensitivity to change is highly uncertain, in particular due to their multiple and complex interactions with aerosols. Hence new cloud observation systems (ground-based and space-borne) are needed for cloud monitoring.

The purpose of the 3MI is to provide multi-spectral (from 410 to 2130 nm), multi-polarisation (-60°, 0°, and +60°), and multi-angular (10 to 14 views) images of the Earth top of atmosphere (TOA) outgoing radiances. First results from the 3MI synthetic data simulator will be presented.

Although aerosol and cloud characterisation is the primary application, 3MI will further support observation of landsurface characteristics which will benefit from the enhanced directional and polarisation measurements and provide a better understanding of the Earth radiation budget.

3MI will also benefit from the synergy of other instruments flying onboard EPS-SG. Measurements from thermal infrared channels will be available from the METimage and IASI-NG instruments. Furthermore, the Sentinel-5 will provide information from the ultra-violet to the shortwave infrared, at a coarser horizontal sampling. The synergy with these instruments will also support 3MI with beneficial cross-calibration as 3MI will not have an onboard calibration and its radiometric performance will rely on vicarious calibration.

The polarizing phase meter system of polycrystalline networks of human blood plasma which is used for the mammary gland pathology diagnostics was proposed in this paper. Increasing the accuracy of the phase value determination was achieved using a combination of low coherent source of radiation and circularly polarized probing of biological object. Thus, high informativity of polarizing phase meter system for the diagnosis of breast pathology using the phase mapping of the human blood plasma films were determined, thereafter statistical, correlational, fractal structure analysis of the obtained phase maps was carried out and the quantitative criterias of the phase diagnostics and differentiation of the breast pathological conditions were determined too.

Imaging polarimeters have been largely used for remote sensing tasks, and most imaging polarimeters are division of time or division of space Stokes polarimeters. Imaging Mueller matrix polarimeters have just begun to be constructed which can take data quickly enough to be useful. We have constructed a Mueller matrix (active) polarimeter utilizing a hybrid modulation approach (modulated in both time and space) based on a micropo- larizer array camera and rotating retarders. The hybrid approach allows for an increase in temporal bandwidth (instrument speed) at the expense of spatial bandwidth (sensor resolution). We present the hybrid approach and associated reconstruction schemes here. Additionally, we introduce the instrument design and some preliminary results and data from the instrument.

Polarization has promising potential to retrieve the information of the steady samples, such as tissues. However, for the fast changing sample such as the suspended algae in the water, the kinetics of the particles also influence the scattered polarization. The present paper will show our recent results to extract the information about the kinetics of the suspended cylindrical particles by polarization measurements. The sample is the aqueous suspension of the glass fibers stirred by a magnetic stirrer. We measure the scattered polarization of the fibers by use of a simultaneous polarization measurement system and obtain the time series of two orthogonal polarization components. By use of correlation analysis, we obtain the time parameters from the auto-correlation functions of the polarization components, and observe the changes with the stirring speeds. Results show that these time parameters indicate the immigration of the fibers. After discussion, we find that they may further characterize the kinetics, including the translation and rotation, of the glass fibers in the fluid field.

Light scattering in atmosphere can change optical polarization properties. Analysis and Measurement on interaction of polarized light with atmospheric particulates can provide important information to evaluate the atmospheric composition and conditions. In this paper, we propose a polarization character focusing on the evaluation of soot content in the air, based on our polarized photon scattering simulation program. The simulation results demonstrate how the polarization parameter at a specific scattering angle can identify the soot particles from the other air pollutants. Compared with nonpolarization optical measurement, polarization characterization can enhance the contrast of distinguishing different type particles and also can be applied in a wide particle size range.