Polymers for IR imaging: The preparation of high refractive index polymers (n = 1.75 to 1.86) via the inverse vulcanization elemental sulfur is reported. High quality imaging in near (1.5 μm) and mid-IR (3–5 regions using polymeric lenses from these materials was demonstrated. As a service our authors readers, this journal provides supporting information supplied by authors. Such are peer reviewed may be re-organized online delivery, but not copy-edited or typeset. Technical support issues...

We present simulation results quantitatively showing that circularly polarized light persists in transmission through several real-world and model fog environments better than linearly over broad wavelength ranges from the visible infrared. for polydisperse particle distributions realistic measured environments, comparing polarization persistence of linear circular polarization. Using a polarization-tracking Monte Carlo program, we simulate propagation four MODTRAN models (moderate heavy...

We find for infrared wavelengths that there are broad ranges of particle sizes and refractive indices represent fog rain, where circular polarization can persist to longer than linear polarization. Using tracking Monte Carlo simulations varying size, wavelength, index, we show that, specific scene parameters, outperforms in maintaining the illuminating state large optical depths. This enhancement with be exploited improve range target detection obscurant environments important many critical...

Biomarkers are widely used in epidemiology, yet there few reliability studies to assess the appropriateness of using these biomarkers for assessment exposure–disease relationships. The aim study was 20 serum collected from two Dutch centres (Utrecht and Bilthoven) participating European Prospective Investigation into Cancer Nutrition (EPIC) at points several years apart. Blood samples were 30 men Bilthoven 35 women Utrecht. Ferritin, total iron, iron-binding capacity, transferrin saturation,...

This work quantifies the polarization persistence and memory of circularly polarized light in forward-scattering isotropic (Rayleigh regime) environments; for first time, details evolution both linearly states through scattering environments. Circularly persists a larger number events longer than all but not Rayleigh regime. Circular polarization's increased occurs forward backscattered light. The simulated environments model polystyrene microspheres water with particle diameters 0.1 μm, 2.0...

Random scattering and absorption of light by tiny particles in aerosols, like fog, reduce situational awareness cause unacceptable down-time for critical systems or operations. Computationally efficient transport models are desired computational imaging to improve remote sensing capabilities degraded optical environments. To this end, we have developed a model based on weak angular dependence approximation the Boltzmann radiative transfer equation that appears be applicable both moderate...

The scattering of light in fog is a complex problem that affects imaging many ways. Typically, device performance attributed solely to reduced visibility measured as extinction from events. We present quantitative analysis resolution degradation the long-wave infrared regime. Our based on calculation modulation transfer function edge response slant blackbody target known conditions. show higher spatial frequencies attenuate more than low with increasing thickness. These results demonstrate...

We find for infrared wavelengths there are clear particle size ranges and indices representative of fog rain where the use circular polarization imaging can penetrate to larger optical depths than linear polarization. Using tracking Monte Carlo simulations varying size, wavelength, index systematically, we show that specific scene parameters vastly outperforms in maintaining degree large transmission reflection. This enhancement be exploited improve obscurant environments important many...

Fogs, low lying clouds, and other highly scattering environments pose a challenge for many commercial national security sensing systems. Current autonomous systems rely on optical sensors navigation whose performance is degraded by environments. In our previous simulation work, we have shown that polarized light can penetrate through environment such as fog. We demonstrated circularly maintains its initial polarization state better than linearly light, even large numbers of events thus...

We present both simulation and experimental results showing that circularly polarized light maintains its degree of polarization better than linearly in scattering environments. This is specifically true turbid environments like fog clouds. In contrast to previous studies propagate single wavelengths through broad particle-size distributions, this work identifies regions where circular persists further linear by systematically surveying different monodisperse particle diameters. For...

A computationally efficient radiative transport model is presented that predicts a camera measurement and accounts for the light reflected blocked by an object in scattering medium. The good agreement with experimental data acquired at Sandia National Laboratory Fog Chamber Facility (SNLFC). applicable computational imaging to detect, localize, image objects hidden media. Here, statistical approach was implemented study detection limits fog.

Scattering environment conditions, such as fog, pose a challenge for many detection and surveillance active sensing operations in both ground air platforms. For example, current autonomous vehicles rely on range of optical sensors that are affected by degraded visual environments. Real-world fog conditions can vary widely depending the location environmental during its creation. In our previous work we have shown benefits increasing signal through scattering environments utilizing polarized...

Degraded visual environments are a serious concern for modern sensing and surveillance systems. Fog is of interest due to the frequency its formation along our coastlines disrupting border security surveillance. presents hurdles in intelligence reconnaissance by preventing data collection with optical systems extended periods. We will present recent results from work operating controlled fog experimental chamber. This facility 180-foot-long, 10-foot-wide, 10-foot-tall structure that has over...

We present simulation and experimental results showing circular polarization is more tolerant of optical collection geometry (field view area) variations than linear for forward-scattering environments. Circular also persists superiorly in the environment compared to by maintaining its degree better through increasing thicknesses. In contrast, both polarizations are susceptible isotropic-scattering (Rayleigh regime) environments, maintains a small advantage persistence. Simulations...

We present simulation results that show circularly polarized light persists through scattering environments better than linearly light. Specifically, we persistence is enhanced many events in an environment with a size parameter representative of advection fog at infrared wavelengths. Utilizing polarization tracking Monte Carlo simulations larger benefit for circular versus linear both forward and backscattered photons. the evolution incident states after various which highlight mechanism...

We present experimental and simulation results for a laboratory-based forward-scattering environment, where 1 μm diameter polystyrene spheres are suspended in water to model the optical scattering properties of fog. Circular polarization maintains its degree better than linear as thickness environment increases. Both experiment quantify circular polarization's superior persistence, compared that polarization, show it is much less affected by variations field view collection area system. Our...

In this paper, we develop a nested chi-squared likelihood ratio test for selecting among shrinkage-regularized covariance estimators background modeling in hyperspectral imagery. Critical to many target and anomaly detection algorithms is the estimation of underlying signal present data. This especially important imagery, wherein signals interest often represent only small fraction observed variance, example when targets are subpixel. modeled by local or global multivariate Gaussian...

We present the characterization of several atmospheric aerosol analogs in a tabletop chamber and an analysis how concentration NaCl these aerosols influences their bulk optical properties. Atmospheric (e.g., fog haze) degrade signal via light-aerosol interactions causing scattering absorption, which can be described by Mie theory. This attenuation is function size distribution number droplets light path. These properties are influenced ambient conditions droplet's composition, as Köhler It...

Heavy fogs and other highly scattering environments pose a challenge for many commercial national security sensing systems. Current autonomous systems rely on range of optical sensors guidance remote that can be degraded by environments. In our previous on-going simulation work, we have shown polarized light increase signal or through environment such as fog. Specifically, circularly maintains its larger number events thus range, better than linearly light. this work present design testing...

Deciding on an imaging modality for terrain classification can be a challenging problem. For some classes given sensing may discriminate well, but not have the same performance other that different sensor able to easily separate. The most effective will utilize abilities of multiple modalities. challenge utilizing modalities is then determining how combine information in meaningful and useful way. In this paper, we introduce framework effectively combining data from optical polarimetric...

Degraded visual environments are a cause of problems for surveillance systems and other sensors due to the reduction in contrast, range, signal. Fog is concern because frequency its formation along our coastlines; disrupting border security, shipping, surveillance, sometimes causing deadly accidents. reduces visibility by scattering ambient/active illumination light obscuring environment limiting operational capability. Sandia has created fog facility characterization testing optical...

We report on the design, modeling, calibration, and experimental results of a LWIR, spectrally temporally resolved broad band bi-directional reflectance distribution function measuring device. The system is built using commercial Fourier transform infrared spectrometer, which presents challenges due to relatively low power output compared laser based methods. instrument designed with sample area that oriented normal gravity, making device suitable for loose powder materials, liquids, or...

The detection, location, and identification of suspected underground nuclear explosions (UNEs) are global security priorities that rely on integrated analysis multiple data modalities for uncertainty reduction in event analysis. Vegetation disturbances may provide complementary signatures can confirm or build the observables produced by prompt sensing techniques such as seismic radionuclide monitoring networks. For instance, emergence non-native species an area be indicative anthropogenic...