Spectral Sciences Incorporated

About: Spectral Sciences Incorporated is a company organization based out in Burlington, Massachusetts, United States. It is known for research contribution in the topics: Hyperspectral imaging & Radiance. The organization has 114 authors who have published 342 publications receiving 10875 citations.

Retrieval of Atmospheric Parameters and Surface Reflectance from Visible and Shortwave Infrared Imaging Spectroscopy Data

Abstract: Remote imaging spectroscopy in the 04–25-μm visible and shortwave infrared (VSWIR) range captures the majority of solar-reflected energy and enables a wide range of earth surface studies This spectral range is also influenced by atmospheric effects including absorption from atmospheric gases and aerosols, Rayleigh scattering, and particle scattering Globally consistent surface measurements must compensate for these atmospheric effects This article reviews the physical and mathematical foundations of modern VSWIR atmospheric retrieval, focusing on imaging spectrometers We assess sensitivity of the retrieval to errors in atmospheric state estimation Finally, we describe some promising avenues of future research to support the next generation of orbital imaging spectrometers

Measurement of molecular concentrations and line parameters using line-locked second harmonic spectroscopy with an AlGaAs diode laser

Abstract: The technique of line-locked wavelength modulation with 2f detection is applied to the measurement of water vapor concentration and absorption line parameters by using an 820-nm AlGaAs communications diode laser. Measurements of the 2f signal as a function of the modulation amplitude yield accurate concentrations and line parameters over a pressure range of an order of magnitude and half-widths from 0.02 to 0.15 cm−1. Using two different spectral lines, we determined concentrations and line parameters with 1% precision, and the absolute accuracy of the line parameters is 3% or better. The results have been used to calculate calibration curves for a diode laser humidity monitor.

Long-wave infrared surface reflectance spectra retrieved from Telops Hyper-Cam imagery

Abstract: Processing long -wave infrared (LWIR) hyperspectral imagery to surface emissivity or reflectance units via atmospheric compensation and temperatureemissivity separation (TES) affords the opportunity to remotely classify and ide- ntify solid materials with minimal interference from atmospheric effects. This paper describes an automated atmospheric compensation and TES method, called FLAASH ® -IR (Fast Line -of -sight Atmospheric Analysis of Spectral Hypecubes – Infrared), and its application to ground-to-ground imagery taken with the Telops Inc . Hyper-Cam interferometric hyperspectral imager. The results demonstrate that clean, quantitative surface spectra can be obtained, even with highly reflective (low emissivity) objects such as b are metal and in the presence of some illumination from the surroundings. In particular, the atmospheric compensation process suppresses the spectral features due to atmospheric water vapor and ozone, which are especially prominent in reflected sky radian ce.

Improved reflectance retrieval from hyper- and multispectral imagery without prior scene or sensor information

Abstract: We describe improvements to a recently developed VNIR-SWIR atmospheric correction method for hyper- and multispectral imagery, dubbed QUAC (QUick Atmospheric Correction). It determines the atmospheric compensation parameters directly from the information contained within the scene using the observed pixel spectra. The newest implementation of QUAC is based on the assumption that the average reflectance of a collection of diverse material spectra, such as the endmember spectra in a scene, is effectively scene independent. This enables the retrieval of reasonably accurate reflectance spectra even when the sensor does not have a proper radiometric or wavelength calibration, or when the solar illumination intensity is unknown. The computational speed of the atmospheric correction method is significantly faster than for the first-principles methods, making it potentially suitable for real-time applications on aircraft and spacecraft. QUAC is applied to a diverse collection of hyper- and multispectral data sets and the results are compared to those obtained with the physics-based atmospheric correction code FLAASH (Fast Line of sight Atmospheric Analysis of Spectral Hypercubes).

Precise determination of the deuteron spin structure at low to moderate Q2 with CLAS and extraction of the neutron contribution

Abstract: In this study, we present the final results for the deuteron spin structure functions obtained from the full data set collected with Jefferson Lab's CLAS in 2000-2001. Polarized electrons with energies of 1.6, 2.5, 4.2 and 5.8 GeV were scattered from deuteron (15ND3) targets, dynamically polarized along the beam direction, and detected with CLAS. From the measured double spin asymmetry, the virtual photon absorption asymmetry Ad1 and the polarized structure function gd1 were extracted over a wide kinematic range (0.05 GeV2 < Q2 < 5 GeV2 and 0.9 GeV < W < 3 GeV). We use an unfolding procedure and a parametrization of the corresponding proton results to extract from these data the polarized structure functions An1 and g1n of the (bound) neutron, which are so far unknown in the resonance region, W < 2 GeV. We compare our final results, including several moments of the deuteron and neutron spin structure functions, with various theoretical models and expectations as well as parametrizations of the world data. The unprecedented precision and dense kinematic coverage of these data can aid in future extractions of polarized parton distributions, tests of perturbative QCD predictions for the quark polarization at large x, a better understandingmore » of quark-hadron duality, and more precise values for higher-twist matrix elements in the framework of the Operator Product Expansion.« less