Precision analysis of arbitrary full-Stokes polarimeters in the presence of additive and Poisson noise. Estimation variances of the main polarimetric parameters Stokes vector, degree of polarization, azimuth, and ellipticity are derived for arbitrary Stokes measurement matrices in the presence of additive and Poisson shot noise. The obtained theoretical expressions, which are rather involved, are checked extensively with Monte Carlo simulations and their physical meaning is interpreted.
The great benefit of these formulas is to enable comparisons of polarimeter architectures on a quantitative basis. As an example, we compare the optimal architectures based on spherical designs with a suboptimal one that may be easier to implement July 1, Journal of the Optical Society of America.
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A, Optics, Image Science, and Vision. SPEX airborne spectropolarimeter calibration and performance.
To improve our understanding of the complex role of aerosols in the climate system and on air quality, measurements are needed of optical and microphysical aerosol. From many studies, it has become evident that a satellite-based multiangle, multiwavelength polarimeter will be essential to provide such measurements. High-resolution reconstruction of shortwave infrared polarimetric images using the intensity information of visible images.
Shortwave infrared SWIR polarimetric imaging has been found very effective in various applications. However, the low resolution of the SWIR camera severely limits the capacity of this technique. Image reconstruction methods have been developed to improve the spatial resolution, but these methods typically do not consider the polarized information that the images may contain.
In this paper, we propose a high-resolution reconstruction method for SWIR images based on the spatial information of visible images without losing polarized information in the SWIR image Experimental validation of D parameter model for droplet sizing using off-axis lidar measurements. Information about the size distribution of liquid droplets in a fog can be retrieved by measuring the backscattering lidar depolarization parameter D in circular polarization. Using a polarimetric off-axis lidar, measurements at different backscattering angles are performed on fogs made of water droplets and of mineral oil.
Estimation of the effective droplet size is obtained using constrained linear inversion. Mie theory is used to calculate the variation in depolarization parameters for different effective droplet sizes Innovative integrated numerical-experimental method for high-performance multispectral Mueller polarimeters based on ferroelectric liquid crystals.
In this work, an original and effective integrated numerical-experimental approach is proposed for building a high-performance multispectral Mueller polarimeter based on ferroelectric liquid crystals FLCs. This method relies on accurate experimental characterization of the optical components specifically selected to construct such a system, combined with a numerical procedure used to optimize it, in the spectral range of interest, by means of a global optimization function. The proposed strategy enabled the construction of an FLC-based Mueller polarimeter in transmission configuration operating between and nm Liquid crystal phase retarders are utilized by photonic devices and imaging systems for various applications, such as tunable filtering, light modulation, polarimetric imaging, remote sensing and quality inspection.
Due to technical difficulties in the manufacturing process, these phase retarders may suffer from spatial non-uniformities, which degrade the performance of the systems. These non-uniformities can be characterized by measuring the spectral transmission at each voltage and each point on the liquid crystal cell, which is time consuming As a state of quantum matter with insulating bulk and gapless surface states, topological insulators TIs have huge potential in optoelectronic devices.
On the other hand, polarization resolution photoelectric devices based on anisotropic materials have overwhelming advantages in practical applications. We show that optical beams propagating in transversally disordered materials exhibit a spin Hall effect and a spin-to-orbital conversion of angular momentum as they deviate from paraxiality. We theoretically describe these phenomena on the basis of the microscopic statistical approach to light propagation in random media, and show that they can be detected via polarimetric measurements under realistic experimental conditions.
Radio emission from a pulsar's magnetic pole revealed by general relativity. Binary pulsars are affected by general relativity GR , causing the spin axis of each pulsar to precess. We reconstruct the sky-projected polarization emission map over the pulsar's magnetic pole and predict the disappearance of the detectable emission by Two tests of GR are performed using this system, including the spin precession for strongly self-gravitating bodies Nonlinear optical properties of collagen type-I are investigated in thin tissue sections of pig tendon as a research model using a complete polarimetric second-harmonic generation P-SHG microscopy technique called double Stokes-Mueller polarimetry DSMP.
Three complex-valued molecular susceptibility tensor component ratios are extracted. A significant retardance is observed between the chiral susceptibility component and the achiral components, while the achiral components appear to be in phase with each other Wavelength-adaptable effective q-plates with passively tunable retardance. Wave retarders having spatially varying optical axes orientations, called q-plates are extremely efficient devices for converting spin to orbital angular momentum of light and for the generation of optical vortices.
Most often, these plates are designed for a specific wavelength and have a homogeneous constant retardance.
The present work provides a polarimetric approach for overcoming both these limitations. We theoretically propose and experimentally demonstrate q-plates with tunable retardance, employing a combination of only standard q-plates and waveplates 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. Snapshot hyperspectral imaging Fourier transform spectropolarimeter Author s : E.
Youngs; M. Kudenov Show Abstract. 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. 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.
Intrinsic coincident full-Stokes polarimeter using stacked organic photovoltaics and architectural comparison of polarimeter techniques Author s : Ruonan Yang ; Pratik Sen; B. O'Connor ; M. 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 S 3 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. The optimization, based on minimizing the condition number of the 4-cell OPV design, showed that a condition number of 2. 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.
Camera characterization for all-sky polarization measurements during the solar eclipse Author s : Taiga Hashimoto; Laura M. Dahl ; Seth A. Laurie; Joseph A. Shaw Show Abstract. A solar eclipse provides a rare opportunity to observe skylight polarization during conditions that are fundamentally different than what we see every day. 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. The daytime polarimetric images were compared to images from an existing all-sky polarization imager and a polarimetric radiative transfer model.
Advances in modeling polarimeter performance Author s : Russell A. Chipman Show Abstract. 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. Rigorous vector wave propagation for arbitrary flat media Author s : Steven P. Bos ; Sebastiaan Y. Haffert; Christoph U. Keller Show Abstract.
Precise modelling of the off-axis point spread function PSF to identify geometrical and polarization aberrations is important for many optical systems. 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.
The capabilities of the code are demonstrated by simulating a converging beam reflecting from a flat aluminium mirror at normal incidence. Polarization modeling and predictions for DKIST part 2: application of the Berreman calculus to spectral polarization fringes of beamsplitters and crystal retarders Author s : David M. Harrington ; Frans Snik ; Christoph U. Keller ; Stacey R.
Sueoka ; Gerard van Harten Show Abstract. We outline polarization fringe predictions derived from a new application of the Berreman calculus for the Daniel K. 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. 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. Single image super-resolution via regularized extreme learning regression for imagery from microgrid polarimeters Author s : Garrett C. Sargent ; Bradley M. Ratliff ; Vijayan K. Asari Show Abstract.
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.
Compressed channeled linear imaging polarimetry Author s : Dennis J. Lee ; Charles F. Craven Show Abstract. 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.
Workshop "Remote sensing in the O2 A-band"
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. Moving towards more intuitive display strategies for polarimetric image data Author s : Bradley M. Ratliff ; J. 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.
Boger ; Andrew Hohne ; Laura M. Dahl ; Paul W. Nugent ; David W. Riesland ; Benjamin Moon ; Carol L. Baumbauer; Orrin Boese ; Joseph A. Shaw ; Wataru Nakagawa Show Abstract. 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 students. Polarization-color mapping strategies: catching up with color theory Author s : Andrew W. Kruse ; Andrey S. Alenin ; Israel J. Vaughn ; J. 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 CAMUCS. For mapping just angle of polarization with HSV hue, the results show clear non-uniformity and implications for how this can misrepresent the data.
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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. Polarization-selective infrared bandpass filter based on a two-layer subwavelength metallic grating Author s : Andrew J. Hohne ; Benjamin Moon ; Carol L. Dickensheets ; Wataru Nakagawa Show Abstract. 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. 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.
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. Achromatic and chromatic liquid crystal polymer films at near-infrared wavelengths Conference Presentation Author s : Nathaniel Z.
Hornburg Show Abstract. 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.
KNMI Research - Satellite observations - Workshop "Remote sensing in the O2 A-band"
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. 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. Fraunhofer line optical correlator for improvement of initial orbit determination Author s : Brett A.
Pantalone ; Michael W. 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. A nine-channeled partial Mueller matrix polarimeter Author s : Andrey S. 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.
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.
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