This PDF file contains the front matter associated with SPIE Proceedings Volume 10407 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Designing polarimetric systems directly in the channel space has provided insight into how to design new types of polarimetric systems, including systems which use carriers in hybrid domains of space, time, or spectrum. Utilizing linear systems theory, we present a full Stokes imaging polarimeter design which has the potential to operate at half the frame rate of the imaging sensor of the system by utilizing a hybrid spatio-temporal carrier design. The design places channels on the faces and the edges of the Nyquist cube resulting in the potential for half the Nyquist limit to be achieved, provided that the spatial frequency of the objects being imaged are bandlimited to less than 0.25 cycles per pixel. If the objects are not spatially bandlimited, then the achievable temporal bandwidth is more difficult to analyze. However, a spatio-temporal tradeoff still exists allowing for increased temporal bandwidth. We present the design of a “Fast Stokes’’ polarimeter and some simulated images using this design.

This paper describes real-time, very small and cheap Stokes polarimeter using three polarized beam splitters (PBSs). Each s1, s2 and s3 of Stokes parameters is measured by the PBSs. However this technique has to separate three beams keeping unknown incidental polarization state. To overcome this problem, three same normal beam splitters (BSs) are possible to separated two beams keeping polarized state. An alignment of three BSs is set orthogonal in transmission part and reflection part. In transmission part, the polarization state after two BSs can be canceled change of polarization state of first BS by change of second orthogonal BS. In reflection part is same theory. If you set two pear of this keeping polarization beam splitter, you can separate three beams keeping incidental polarization state. After separated beams, three PBS can measure Stokes parameters easily. At first we checked effect of the keeping polarization beam splitter using spectoscopic Mueller matrix polarimeter. We got Mueller matrixes having max 3.3% value of transmission and reflection from unit matrix during from 450nm to 700nm. In second we checked Stokes parameters after a rotating polarizer and a quarter wave plate in this Stokes polarimeter. In two condition results, an error had 5.6%. Finally we checked measurement speed of this real-time Stokes polarimeter using rotating quarter wave plate. From this result this Stokes polarimeter is possible to measure Stokes parameter in 15Hz. This measurement speed depends on detection speed of six PIN photodiodes and transfer speed of AD convertor.

The design and experimental results of a snapshot spatially heterodyned imaging Fourier transform (SHIFT) spectropolarimeter are presented. The sensor utilizes common-path interferometry, which lends improved compactness and ruggedness over free-space interferometric techniques. The polarization-dependency of the optical instrument can also be leveraged to obtain both spectral and polarimetric measurements. In this paper, calibration procedures and the SHIFT data processing algorithms are described. A data-reduction matrix is utilized to transform the measured per-pixel interferograms into corresponding Stokes parameters. Using this matrix, neural networks are trained to automate the transformation process from measurement to Stokes parameters. Finally, preliminary experimental results of the SHIFT’s ability to distinguish certain spectral signatures are demonstrated.

An intrinsic coincident full-Stokes polarimeter is demonstrated by using stain-aligned polymer-based organic photovoltaics (OPVs) which can preferentially absorb certain polarized states of incident light. The photovoltaic-based polarimeter is capable of measuring four stokes parameters by cascading four semitransparent OPVs in series along the same optical axis. Two wave plates were incorporated into the system to modulate the S₃ stokes parameter so as to reduce the condition number of the measurement matrix. The model for the full-Stokes polarimeter was established and validated, demonstrating an average RMS error of 0.84%. The optimization, based on minimizing the condition number of the 4-cell OPV design, showed that a condition number of 2.4 is possible. Performance of this in-line polarimeter concept was compared to other polarimeter architectures, including Division of Time (DoT), Division of Amplitude (DoAm), Division of Focal Plane (DoFP), and Division of Aperture (DoA) from signal-to-noise ratio (SNR) perspective. This in-line polarimeter concept has the potential to enable both high temporal (as compared with a DoT polarimeter) and high spatial resolution (as compared with DoFP and DoA polarimeters). We conclude that the intrinsic design has the same ~√2 SNR advantage as the DoAm polarimeter, but with greater compactness.

A solar eclipse provides a rare opportunity to observe skylight polarization during conditions that are fundamentally different than what we see every day. On 21 August 2017 we will measure the skylight polarization during a total solar eclipse in Rexburg, Idaho, USA. Previous research has shown that during totality the sky polarization pattern is altered significantly to become nominally symmetric about the zenith. However, there are still questions remaining about the details of how surface reflectance near the eclipse observation site and optical properties of aerosols in the atmosphere influence the totality sky polarization pattern. We will study how skylight polarization in a solar eclipse changes through each phase and how surface and atmospheric features affect the measured polarization signatures. To accomplish this, fully characterizing the cameras and fisheye lenses is critical. This paper reports measurements that include finding the camera sensitivity and its relationship to the required short exposure times, measuring the camera’s spectral response function, mapping the angles of each camera pixel with the fisheye lens, and taking test measurements during daytime and twilight conditions. The daytime polarimetric images were compared to images from an existing all-sky polarization imager and a polarimetric radiative transfer model.

Artifacts in polarimeters are apparent polarization features which are not real but result from the systematic errors in the polarimeter. The polarization artifacts are different between division of focal plane, spectral, and time modulation polarimeters. Artifacts result from many sources such as source properties, micropolarizer arrays, coatings issues, vibrations, and stress birefringence. A modeling examples of polarization artifacts due to a micro-polarizer array polarimeter is presented.

Conventional ray tracing calculates the shape of wavefronts, but not their amplitudes or polarization states. Thin films, polarizers, diffraction gratings, crystals and even lenses, in addition to affecting the shape of wavefronts make contributions to the relative phase and amplitude of the light in an Optical System. These contributions will vary with polarization, field, and pupil position, adversely affecting the system performance. For sensitive optical systems, it is necessary to design around these effects with polarization ray tracing algorithms which are not only related to the optical path length, but include polarization dependent surface effects. This is done by supplementing the optical path length with calculations of the polarization ray tracing matrix (PRT). The adverse effects can then be described as the deviations from an identity Jones Pupil (polarization aberration), and Zernike polynomials can then be used to provide a simplified generalization of the polarization aberration that is still accurate. The Zernike terms will describe the amplitude transmission along the ray paths, the amplitude aberration, which is normally unavailable with a geometrical ray trace, and the Zernike terms will have the relative phase accumulations along ray paths, that describe phase variation with polarization state. Three different optical elements will be modeled: a wire grid polarizer, an anisotropic diffraction grating, and an injection molded lens with the polarization ray tracing software, Polaris-M. For each optical element, the polarization aberrations will be calculated and fit to Zernike polynomials. The effects of the aberrations on system performance will then be discussed and categorized.

Precise modelling of the (off-axis) point spread function (PSF) to identify geometrical and polarization aberrations is important for many optical systems. In order to characterise the PSF of the system in all Stokes parameters, an end-to-end simulation of the system has to be performed in which Maxwell’s equations are rigorously solved. We present the first results of a python code that we are developing to perform multiscale end-to-end wave propagation simulations that include all relevant physics. Currently we can handle plane-parallel near- and far-field vector diffraction effects of propagating waves in homogeneous isotropic and anisotropic materials, refraction and reflection of flat parallel surfaces, interference effects in thin films and unpolarized light. We show that the code has a numerical precision on the order of ~ 10^-16 for non-absorbing isotropic and anisotropic materials. For absorbing materials the precision is on the order of ~ 10^-8. The capabilities of the code are demonstrated by simulating a converging beam reflecting from a flat aluminium mirror at normal incidence.

We outline polarization fringe predictions derived from a new application of the Berreman calculus for the Daniel K. Inouye Solar Telescope (DKIST) retarder optics. The DKIST retarder baseline design used 6 crystals, singlelayer anti-reflection coatings, thick cover windows and oil between all optical interfaces. This new tool estimates polarization fringes and optic Mueller matrices as functions of all optical design choices. The amplitude and period of polarized fringes under design changes, manufacturing errors, tolerances and several physical factors can now be estimated. This tool compares well with observations of fringes for data collected with the SPINOR spectropolarimeter at the Dunn Solar Telescope using bi-crystalline achromatic retarders as well as laboratory tests. With this new tool, we show impacts of design decisions on polarization fringes as impacted by anti-reflection coatings, oil refractive indices, cover window presence and part thicknesses. This tool helped DKIST decide to remove retarder cover windows and also recommends reconsideration of coating strategies for DKIST. We anticipate this tool to be essential in designing future retarders for mitigation of polarization and intensity fringe errors in other high spectral resolution astronomical systems.

We present a method of calculating analytic formulas for the second-order statistics - the signal, variance, and SNR - of a variety of linear Stokes polarization measurement techniques. The advantage of the method is that it is easy to perform and can be used to produce analytic rather than numeric results. Using the derived formulae, we compare a number of different polarimetric designs.

The advantage of division of focal plane imaging polarimeters is their ability to obtain temporally synchronized intensity measurements across a scene; however, they sacrifice spatial resolution in doing so due to their spatially modulated arrangement of the pixel-to-pixel polarizers and often result in aliased imagery. Here, we propose a super-resolution method based upon two previously trained extreme learning machines (ELM) that attempt to recover missing high frequency and low frequency content beyond the spatial resolution of the sensor. This method yields a computationally fast and simple way of recovering lost high and low frequency content from demosaicing raw microgrid polarimetric imagery. The proposed method outperforms other state-of-the-art single-image super-resolution algorithms in terms of structural similarity and peak signal-to-noise ratio.

Channeled linear imaging polarimeters measure the two-dimensional distribution of the linear Stokes parameters. A key aspect of this technique is to accurately reconstruct the Stokes parameters from a snapshot, modulated measurement of the channeled linear imaging polarimeter. The state-of-the-art reconstruction takes the Fourier transform of the measurement to separate the Stokes parameters into channels. While straightforward, this approach is sensitive to channel cross-talk and imposes bandwidth limitations that cut off high frequency details. To overcome these drawbacks, we present a reconstruction method called compressed channeled linear imaging polarimetry. In this framework, reconstruction in channeled linear imaging polarimetry is an underdetermined problem, where we measure N pixels and recover 3N Stokes parameters. We formulate an optimization problem by creating a mathematical model of the channeled linear imaging polarimeter with inspiration from compressed sensing. Through simulations, we show that our approach mitigates artifacts seen in Fourier reconstruction, including image blurring and degradation and ringing artifacts caused by windowing and channel cross-talk. By demonstrating more accurate reconstructions, we push performance to the native resolution of the sensor, allowing more information to be recovered from a single measurement of a channeled linear imaging polarimeter.

The display of polarimetric imaging data has been a subject of considerable debate. Display strategies range from direct display of the Stokes vector images (or their derivatives) to false color representations. In many cases, direct interpretation of polarimetric image data using traditional display strategies is not intuitive and can at times result in confusion as to what benefit polarimetric information is actually providing. Here we investigate approaches that attempt to augment the s0 image with polarimetric information, rather than directly display it, as a means of enhancing the baseband s0 image. The benefit is that the polarization-enhanced visible or infrared image maintains a familiar look without the need for complex interpretation of the meaning of the polarimetric data, thus keeping the incorporation of polarimetric information transparent to the end user. The method can be applied to monochromatic or multi-band data, which allows color to be used for representing spectral data in multi- or hyper-spectropolarimetric applications. We take a more subjective approach to image enhancement than current techniques employ by simply seeking to improve contrast and shape information for polarized objects within a scene. We find that such approaches provide clear enhancement to the imagery when polarized objects are contained within the scene without the need for complex interpretation of polarization phenomenology.

Getting students interested in science, specifically in optics and photonics, is a worthwhile challenge. We developed and implemented an outreach campaign that sought to engage high school students in the science of polarized light. We traveled to Montana high schools and presented on the physics of light, the ways that it becomes polarized, how polarization is useful, and how to take pictures with linear polarizers to see polarization. Students took pictures that showed polarization in either a natural setting or a contrived scene. We visited 13 high schools, and presented live to approximately 450 students.

Current visualization techniques for mapping polarization data to a color coordinates defined by the Hue, Saturation, Value (HSV) color representation are analyzed in the context of perceptual uniformity. Since HSV is not designed to be perceptually uniform, the extent of non-uniformity should be evaluated by using robust color difference formulae and by comparison to the state-of-the-art uniform color space CAM02-UCS. For mapping just angle of polarization with HSV hue, the results show clear non-uniformity and implications for how this can misrepresent the data. UCS can be used to create alternative mapping techniques that are perceptually uniform. Implementing variation in lightness may increase shape discrimination within the scene. Future work will be dedicated to measuring performance of both current and proposed methods using psychophysical analysis.

We present the design, fabrication, and characterization of a polarization-selective infrared bandpass filter based on a two-layer subwavelength metallic grating for use in polarimetric imaging. Gold nanowires were deposited via physical vapor deposition (PVD) onto a silicon surface relief grating that was patterned using electron beam lithography (EBL) and fabricated using standard silicon processing techniques. Optical characterization with a broad-spectrum tungsten halogen light source and a grating spectrometer showed normalized peak TM transmission of 53% with a full-width at half-maximum (FWHM) of 122 nm, which was consistent with rigorous coupled-wave analysis (RCWA) simulations. Simulation results suggested that device operation relied on suppression of the TM transmission caused by surface plasmon polariton (SPP) excitation at the gold-silicon interface and an increase in TM transmission caused by a Fabry-Perot (FP) resonance in the cavity between the gratings. TE rejection occurred at the initial air/gold interface. We also present simulation results of an improved design based on a two-dielectric grating where two different SPP resonances allowed us to improve the shape of the passband by suppressing the side lobes. This newer design resulted in improved side-band performance and increased peak TM transmission.

Certain wavelengths bands, especially Y, J, H, and K, have become the main measurement pathway for many of the world’s largest telescopes. Additionally, the study of stellar light within of near-infrared (NIR) bands has become the staple in the field of direct imaging. Because of this, there is a growing necessity for customized broadband optics in the near infrared to meet the needs of the astronomers and allow for more precise measurements. We report on complex birefringent films developed for NIR operation, useful to implement wave-plates, vector apodizing phase plates, and polarization gratings. The combination of multi-twist retarders (MTRs) with both direct-write laser scanning or holographic lithography, and allows us to fabricate arbitrary phase patterns via a geometric phase effect and achromatic, super-achromatic, and highly chromatic (dual-band) spectra from 0.5 to 5 microns. MTRs are complex birefringent films with an optic axis variation along 1D/2D/3D. They consist of two or more chiral liquid crystal (LC) layers on a single substrate and with a single photo-alignment layer. Importantly, subsequent LC layers are aligned directly by prior layers, allowing simple fabrication, achieving automatic layer registration, and resulting in a monolithic film with a continuously varying optic axis. MTRs can be used for a wide range of remote optical sensing, both earth- and space-based. Here, we will review our current and prior MTR films being used for NIR astronomical observation, and discuss the realistic opportunities and limitations ahead for improved precision and design-complexity for retardation and wavefront(phase).

The design of a Fraunhofer line optical correlator is detailed. The instrument described herein correlates a reflected solar spectrum against multiple Fraunhofer absorption lines to estimate the radial velocity of the reflecting body. By using a spatial light modulator (SLM) as a photomask for known solar absorption lines in the visible spectrum, the ratio of Doppler shifted solar energy to the total received energy can be calculated. Although the reflected light from targets in high orbit is weak, signal-to-noise ratio (SNR) is enhanced by the measurement of multiple Fraunhofer lines in a single snapshot image. Simulations indicate that prediction of orbital parameters is improved by incorporation of this velocity information, and in some cases the number of line-of-sight measurements can be reduced from three to two.

We have recently introduced channeled-partial Mueller matrix polarimeters as a potential design for measuring a limited number of Mueller elements for remote sensing discrimination. Because in such systems the polarization information is modulated in space or spectrum, the corresponding carrier domain ends up sharing two different types of information, thus leading to a reduction of bandwidth for each. In this work, we concentrate on an efficient nine-channel/nine-reconstructables design, which limits the associated resolution loss by limiting the overall complexity of the system. Employing structured decomposition techniques allows us to produce a system description that provides an analytically deducible set of reconstructables that include 𝑚00, any two linear combinations of the elements within the diattenuation vector, any two linear combinations of the elements within the polarizance vector, as well as the linear combinations specified by the Kronecker product of the diattenuation and polarizance vectors. Finally, we optimize the available polarimeter parameters to align the nine reconstructables with the desirables derived from sample data, while maintaining the ability to discriminate between different objects.

This paper describes hyperspectroscopic Mueller-matrix polarimeters based on channeled polarimetry. The channeled polarimetry is a method for measuring polarimetric parameters using a cosinusoidally-modulated spectrum. We previously reported on a snapshot spectroscopic Mueller-matrix polarimeter based on channeled polarimetry. In this article, we describe its expansion for the hyperspectroscopic Mueller-matrix measurement. The hyperspectroscopic image obtained from the system includes components cosinusoidally modulated along both wavenumber- and space-axes which carry the information of sixteen Mueller-matrix elements of the sample under measurement. The Fourier analysis of the hyperspectroscopic image allows us to demodulate the spatially and spectrally resolved Mueller matrix of the sample. This method has a feature that it requires neither mechanical nor active components for polarization modulation. We assembled two systems for the demonstration. The first system uses a wavelength-scanning source for the hyperspectroscopic Mueller matrix measurement. In contrast, the second system incorporates a grating spectrometer for the snapshot measurement of a Mueller matrix as a function of one-dimensional spatial position and wavelength. The feasibility of both systems was demonstrated in the visible region.

At any given time, clouds cover approximately 60% of the Earth’s surface and they strongly influence weather and climate; however, they are one of the largest sources of uncertainty in climate models and predictions of atmospheric effects on remote sensing measurements. Knowing the cloud thermodynamic phase – whether a cloud is composed of ice crystals or liquid particles – is critical in these applications. Knobelspiesse et al. (Atmos. Meas. Tech., 8, 1537–1554, 2015) showed theoretically that the sign of the S1 Stokes parameter can be used to detect cloud thermodynamic phase when observed with a ground-based passive polarimeter and demonstrated this principle with a zenith-viewing polarimeter. In this theory, a positive S₁ value indicates a liquid cloud, while a negative S₁ value indicates an ice cloud. In this paper, we report the use of our all-sky polarimeter, operating at 450 nm (10 nm band) to detect ice, liquid, and multi-layered clouds. The cloud thermodynamic phase was independently verified with a dual-polarization lidar pointed at the zenith.

The polarization-sensitive spectral domain optical coherence tomography (PSOCT) has the advantages of being able to measure the polarization properties of samples, such as phase-retardation, diattenuation, depolarization, and optical axis orientation, providing a contrast to identify the diseased area and normal area in tissues in PSOCT images. Conventionally, the sample arm of PSOCT is fixed on the stage where biomedical tissues or models is placed, and the OCT images is acquired by scanning with a galvanometer-based mirror. To be applied in the practical diagnosis, a promising way is to design a hand-held device. To this end, it is required that probe is assembled with a small volume to allow for comprehensively imaging large tissues areas at a microscopic scale, and is available to move on different samples to be acquired quickly with negligible motion artifacts. Meanwhile, the probe should be manufactured wih well stability to avoid system jitter error while it is used to detect the biological tissues in vivo. In this work, a design of a hand-hold fiber-based PSOCT is described. The device is of the size of 10 cm (length) × 8 cm (width) × 6 cm (height). Both the axial resolution and the imaging depth of the system are measured and were approximately 7 μm and 2.5 mm in air, respectively, which are in good agreement with the theoretical predictions. The A-scan rate of the system is 70 kHz. The structure is compact and all the components are fixed on the shell to reduce the motion artifact, resulting in a great stability on measuring the tissues in vivo. The cross sectional images of ex vivo chicken breast, ex vivo pork cartilage and in vivo forearm skin of human wolunteer are presented to demonstrate the capability of the system.

Polarimetric LIDAR is a significant tool for current remote sensing applications. In addition, measurement of the full waveform of the LIDAR echo provides improved ranging and target discrimination, although, data storage volume in this approach can be problematic. In the work presented here, we investigated the practical issues related to the implementation of a full waveform LIDAR system to identify polarization characteristics of multiple targets within the footprint of the illumination beam. This work was carried out on a laboratory LIDAR testbed that features a flexible arrangement of targets and the ability to change the target polarization characteristics. Targets with different retardance characteristics were illuminated with a linearly polarized laser beam and the return pulse intensities were analyzed by rotating a linear analyzer polarizer in front of a high-speed detector. Additionally, we explored the applicability and the limitations of applying a sparse sampling approach based on Finite Rate of Innovations (FRI) to compress and recover the characteristic parameters of the pulses reflected from the targets. The pulse parameter values extracted by the FRI analysis were accurate and we successfully distinguished the polarimetric characteristics and the range of multiple targets at different depths within the same beam footprint. We also demonstrated the recovery of an unknown target retardance value from the echoes by applying a Mueller matrix system model.

We report the design of a free-space active infrared polarimetric imaging demonstrator operating at 1.55 μm and based on a non-conventional approach: the orthogonality breaking sensing technique. Relying on the illumination of a scene with a specific light source, the imager offers an original tradeoff between image acquisition time (~ 1 s) and polarimetric consistency in comparison to standard polarimetric imagers such as division of time or division of amplitude systems. We will illustrate the capability of such an imager to enhance the visibility of hidden objects on homemade scenes.

Polarization measurements can be used to distinguish different objects. In this work, polarimetry has been used as a useful tool to differentiate between two geometries, viz., a cube and a cylinder, demonstrating that polarization “signatures” can be obtained from the reflection of passive lighting. A novel approach to characterizing geometries using vector-vector space has been demonstrated to be effective in differentiating between these two geometries and lends itself well to a statistical analysis that is applicable for computer generated target identification.

An important task for remote sensing applications is the characterization of material properties, which can be accomplished by estimating physics-based parameters from optical scattering off a target’s surface. In this paper, a novel approach is described to generate parameter-based images by applying the modified polarimetric bidirectional reflectance distribution function (pBRDF) model to the polarimetric imaging measurements collected with the University of Arizona’s Ground Multiangle SpectroPolarimetric Imager (Ground-MSPI). Values for complex refractive index (η), slope variance roughness (σ²) and diffuse scattering coefficient (ρ_d) for each pixel are jointly estimated. Images consisting of the parameter values are generated by using the estimation results and optimized by contrast-ratio enhancement algorithms. The approach offers significant potential for remote targets analysis and novel imaging technology development.

The Gemini Planet Imager (GPI) is a near-infrared high-contrast imager on the 8-m Gemini South telescope, optimized for the direct detection and characterization of extrasolar Jovian-mass planets and circumstellar disks. The instrument includes a dual-channel polarimetry mode designed to detect the inherently polarized light scattered off debris disks and protoplanetary disks and suppress unpolarized light from the host star. GPI has imaged over two dozen circumstellar disks {detecting some for the first time in scattered light {and carried out polarimetric measurements of brown dwarfs and exoplanets. Here, we review the current status of the debris disk component of the GPI Exoplanet Survey and report on updates to standard data reduction techniques that improve upon the achievable polarimetric contrasts.

We have developed a laboratory spectropolarimeter built to characterize the transmissive and reflective polarization properties of the Daniel K. Inouye Solar Telescope (DKIST) optical components. This includes the full Mueller matrix of retarders, polarizers, mirrors, dichroic coatings, and other optical elements that introduce polarization effects. Characterization is performed at various angles of incidence from 400nm to 1650nm with ~9nm spectral resolution and statistical noise limits >5000 using many automated stages. With this data set, we present tolerance analysis of typical as-built DKIST optics.

We present the design and characterization of a quasi-homogeneous, planar electromagnetic source to produce beam-like optical fields with controllable spatial coherence and polarization properties. Dynamic control of the second-order correlation properties of an optical beam is achieved by controlling the spectral density and polarization state distributions at the source plane, as described by the generalized van Cittert-Zernike theorem for the cross-spectral density matrix of a quasi-homogeneous, planar electromagnetic source. In the proposed design, the spectral density distributions of orthogonal linear polarization components at the quasi-homogeneous source are controlled using a spatial light modulator. The beam generated in this way propagates to the far-field region yielding the desired spatial coherence and polarization state distributions. With this source we can generate an optical beam that is unpolarized in the usual one-point polarization sense, but polarized in the two-point mutual polarization sense. That is, the beam has a polarization distribution where two orthogonal linear polarization components at two points, within the aperture of the beam, separated by a set vector, given by the spectral density distribution at the source, are fully correlated. A beam with that polarization distribution may be used to perform the measurements required by variable coherence polarimetry, which can be applied to estimate the polarimetric bidirectional reflectance distribution function from monostatic measurements, with promising applications in remote sensing.

Traditionally, the partially-polarized light is characterized by the four Stokes parameters. Equivalent description is also provided by correlation tensor of the optical field. These statistics specify only the second moments of the complex amplitudes of the narrow-band two-dimensional electric field of the optical wave. Electric field vector of the random quasi monochromatic wave is a nonstationary oscillating two-dimensional real random variable. We introduce a novel statistical description of these partially polarized waves: the Period-Averaged Probability Density Function (PA-PDF) of the field. PA-PDF contains more information on the polarization state of the field than the Stokes vector. In particular, in addition to the conventional distinction between the polarized and depolarized components of the field PA-PDF allows to separate the coherent and fluctuating components of the field. We present several model examples of the fields with identical Stokes vectors and very distinct shapes of PA-PDF. In the simplest case of the nonstationary, oscillating normal 2-D probability distribution of the real electrical field and stationary 4-D probability distribution of the complex amplitudes, the newly-introduced PA-PDF is determined by 13 parameters that include the first moments and covariance matrix of the quadrature components of the oscillating vector field.

Remotely sensing plant canopy water status remains a long term goal of remote sensing research. Established approaches to estimating canopy water status — the Crop Water Stress Index, the Water Deficit Index and the Equivalent Water Thickness — involve measurements in the thermal or reflective infrared. Here we report plant water status estimates based upon analysis of polarized visible imagery of a cotton canopy measured by ground Multi-Spectral Polarization Imager (MSPI). Such estimators potentially provide access to the plant hydrological photochemistry that manifests scattering and absorption effects in the visible spectral region.

We describe the design and performance of a spectropolarimetric instrument, called TreePol, that is dedicated to remote sensing of the circular polarization signatures due to homochirality in photosynthetic organisms. To ensure high polarimetric sensitivity to observe such signatures, we combine rapid modulation offered by a Ferroelectic Liquid Crystal with a dual-beam spectrometer that incorporates fast line-detectors. The latter also furnishes relatively short measurement times through spectral multiplexing. We introduce several mitigation steps to correct for potential cross-talk from much stronger linear polarization signals into the measured circular polarization spectra. We present first laboratory results for (decaying) leaves and microbes, and we provide an outlook for field-work. In addition to providing a unique look into chiral photosystems of life on Earth, we aim to pave the way towards a unique detection method for extraterrestrial life.

Passive millimeter-wave (PMMW) imaging has been widely adopted in earth remote sensing and security screening applications. To obtain more information about the interested objects, polarimetric measurement is an important approach. In this paper, the polarization characteristics of several common structures (i.e., sphere, cone, cylinder and human) have been analyzed theoretically and the corresponding physical meanings have been revealed. The analyzed polarization feature parameters include Stokes vector, angle of polarization, degree of linear polarization, and linear polarization ratio. Additionally, the indoor and outdoor simulations have been conducted to display the influence of ambient radiation on the polarization characteristics. The simulation results can provide some intrinsic mechanisms to acquire objects information, such as 3D structure feature and material composition.

Active polarization imaging technology has recently become the hot research field all over the world, which has great potential application value in the military and civil area. By introducing active light source, the Mueller matrix of the target can be calculated according to the incident light and the emitted or reflected light. Compared with conventional direct detection technology, optical heterodyne detection technology have higher receiving sensitivities, which can obtain the whole amplitude, frequency and phase information of the signal light. In this paper, an active polarization imaging system will be designed. Based on optical heterodyne balanced receiver, the system can acquire the horizontal and vertical polarization of reflected optical field simultaneously, which contain the polarization characteristic of the target. Besides, signal to noise ratio and imaging distance can be greatly improved.

We introduce partial Mueller matrix polarimeter using two photoelastic modulators and polarizer pairs. Photoelastic modulators (PEMs) have been used in various kinds of polarization measurement techniques for many years, for example in polarimetry and ellipsometry. The advantages of instruments using PEMs are their high-sensitivity and highspeed measurement of polarization properties. A polarized light beam passing through the center of the fused silica bar will experience a periodic phase retardation because of the photoelastic effect which is the basis operation of PEM. In the two PEM-polarizer pairs, Mueller matrix elements of a sample are determined based on the analysis of the frequencies of the time-dependent light beam. Each PEM is operated at different resonant frequencies of 59.85 kHz and 50.07 kHz and are oriented 45° apart. The polarization information that are to be represented by Mueller matrix is distributed based on combinations of two resonant frequencies of operating PEMs. Mueller algebra is used to analyze the optical configuration of the proposed system. The changing variables inside the proposed system will be only the orientations of the azimuthal angle of polarizer and analyzer whereas orientations for both PEMs are fixed. Polarization information such as total retardation can be retrieved by using the partial Mueller matrix information based on the proposed polarimeter. Experimental results of a quarter wave plate will be presented showing the characteristics of the implementation.

The combined method of Jones-Mueller matrix mapping and blood plasma films analysis based on the system that proposed in this paper. Based on the obtained data about the structure and state of blood plasma samples the diagnostic conclusions can be make about the state of breast cancer patients (“normal” or “pathology”). Then, by using the statistical analysis obtain statistical and correlational moments for every coordinate distributions; these indicators are served as diagnostic criterias. The final step is to comparing results and choosing the most effective diagnostic indicators. The paper presents the results of Mueller-Jones matrix mapping of optically thin (attenuation coefficient ,τ≤0,1) blood plasma layers.