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.

Conceptual design of an acquisition, processing, and control system for a semi-autonomous airborne differential absorption lidar system

Abstract: The Air Force Research Laboratory (AFRL) Laser Remote Optical Sensing (LROS) program has developed the LaserAirborne Remote Sensing (LARS) system for chemical detection using the differential absorption lidar (DIAL) technique. Airborne tests during the last year resulted in chemical detection at a slant range of 30 km. As the next step in the development process, concepts for a compact, semi-autonomous DIAL system are being considered. This paper describes theconceptual design and external interfaces of the acquisition, processing, and control system computers required to operate asemi-autonomous DIAL system.The conceptual design ofthe VME-based real-time computer system uses three CPUs: 1) a data acquisition and control CPUwhich synchronizes experiment timing and pulsed CO2 laser operation while controlling lidar subsystem components such aspointing and tracking, wavelength sequencing, and optical alignment; 2) a data reduction CPU which serves as the semi-autonomous controller and performs real-time data reduction; and 3) a data analysis CPU which performs chemometricanalysis including chemical identification and concentration. The triple-CPU and multi-layered software decouple time-critical and non-critical tasks allowing great flexibility in flight-time display and processing.Keywords: airborne, autonomy, DIAL, real time, remote sensing

Detection of cirrus clouds at 1.13 μm in AVIRIS scenes over land

Abstract: Scattered solar radiance from cirrus clouds has traditionally been detected over land at 1.37 micrometer, a wavelength that is ordinarily opaque to the surface due to water vapor absorption. We describe a new pairwise regression method for spectral imagery that retrieves cloud signals in the vicinity of a partially transmitting band, such as the 1.13 micrometer band, over any type of spatially structured terrain. The method, which uses spatial filtering and linear regression to cancel the surface background, has been applied to several rural and urban AVIRIS scenes. With a single cloud or cloud layer in the scene, the 1.13 micrometer and 1.37 micrometer cloud signals are closely correlated. Since the two signals are absorbed differently by water vapor, the slope of the correlation plot indicates the column water vapor above the cloud and thus the approximate cloud altitude. The less strongly absorbed 1.13 micrometer signal is closely related to the cloud optical thickness and can be used by itself or in combination with the 1.37 micrometer signal to correct apparent surface reflectance spectra for cirrus cloud effects.

Modtran ® 6 Multiple Line-Of-Sight (MLOS) Option

Abstract: The MODTRAN6 radiative transfer model enjoys widespread use throughout the remote sensing community. A multiple line-of-sight option is now available that dramatically increases processing time when spectral transmittances and radiances are required for multiple paths within a scene. The option is demonstrated for three applications: (1) modeling residuals between plane-parallel and spherical earth atmosphere hemispherical fluxes; (2) computing wave boundary layer weighting functions; and (3) generating look-up tables for simulating an airborne visible through shortwave infrared hyperspectral sensor.

Structure in middle and upper atmospheric infrared radiance

Abstract: An extensive database on spatial structure in the infrared radiance of the middle and upper atmosphere has been collected by the Mid-Course Space Experiment (MSX). The observed radiance contains spatial structure down to the scale of hundreds of meters. This spatial structure results from local fluctuations in the temperature and densities of the radiating states of the emitting molecular species as well as fluctuations in radiation transport from the emitting regions to the observer. A portion of this database has been analyzed to obtain statistical parameters characterizing stochastic spatial structure in the observed radiance. Using simple models, the observed statistics have been shown to agree with prior observations and theoretical models of stochastic spatial structure generated by gravity waves for special viewing geometries. The SHARC model has been extended to predict the statistics of stochastic fluctuations in infrared radiance from the statistics characterizing temperature fluctuations in the middle and upper atmosphere for arbitrary viewing geometries. SHARC model predictions have been compared with MSX data and shown to be in generally good agreement. Additional work is in progress to account for the statistics characterizing small spatial scale fluctuations.

Development of Electrically Conductive Poly(3-Hexylthiophene) as a Thin Film Sensor for Hydrazine Vapor

Abstract: Thin films of the electrically conducting polymer, poly(3-hexylthiophene) (P3HT), were developed as sensors for hydrazine vapor at the part-per-billion level. The P3HT films were fabricated by a spin coating technique onto quartz substrates incorporating gold interdigitated electrodes, and were rendered conductive by doping with an NOPF6 solution. The sensors respond strongly and instantaneously to hydrazine concentrations as low as 1 part-per-billion with a measurement accuracy of ±20%. In addition, the sensors exhibited excellent environmental stability, long shelf life, and good interference rejection.