spectral reflectance pattern

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1979). In general, M(λ) is experimentally determined by measuring blackbody radiation at various temperatures. Commercially purchased reflectance spectrophotometers are supplied with the correction equations either built in to the instrument’s computer or in computer software supplied with the instrument. Instrument manufacturers supply white calibration standards having known reflectance factors. The spectrum of asteroid 3908 Nyx (Fig. 9 Citations. Copyright © 2020 Elsevier B.V. or its licensors or contributors. [See Main-Belt Asteroids.]. Although single beam instruments offer a simpler design with fewer optical components and higher sensitivity (Zwinkels 1989), they generally did not possess the stability of a double beam instrument. This does not directly provide the full spectrum of ɛ(λ, T). Therefore, a simultaneous spectrum of the Sun (or the reflection spectrum from an object whose spectrum is well understood) must be gathered at the same time that any ultraviolet observations are undertaken. Lucy A. McFadden, Richard P. Binzel, in Encyclopedia of the Solar System (Second Edition), 2007. 13) is dominated by pyroxene and has the same spectral characteristics as the basaltic achondrite meteorites. P.Box 4, Klong Luang, Pathumthani. Spectrophotometers have been made in all four of the CIE recommended illuminating and viewing geometries. Maria E. Nadal, ... Clarence J. Zarobila, in Experimental Methods in the Physical Sciences, 2014. This can introduce sample recess errors. To ensure accurate reflectance factor measurements, the calibration standards should be cleaned or replaced regularly. The approach was first described by Robertson [47] and further investigated by Berns and Petersen [39] who employed multivariate regression. The uncertainty associated with the quantitative description of the color of an object is often necessary for determining the acceptability of that object for its intended application. (5.6). Reflectance measurements and reports are best made using standardized procedures (SAE 0001; ASTM 0016, 0017, 0018, 0020, 0021, 0022; AATCC 0002; American National Standard 1899). The measurement sequence must be completed in its entirety without interruption. The coefficients represent the sensitivity coefficients in this diagnostic model of the systematic errors. (2.57). The spectral calibration of the instrument usually involves a separate spectral characterization and correction of the excitation and emission units, where the excitation unit encompasses the light source, excitation monochromator, and all other instrument components before the sample, and the emission unit encompasses the emission monochromator, analyzing detector, and all other instrument components following the sample. Using multiple wavelengths allows the measurement of the optical constants of the growing film [316] and use of the virtual interface model of Breiland et al. One means of increasing the stability of a spectrophotometer is to use a double beam optical design. The range of variations in mineral composition reflects that seen in the Main Asteroid Belt, indicating that NEOs are mostly derived from the Main Belt. The measured spectrum of a body can thus reveal significant information on the composition of, and processes occurring within, planetary surfaces and atmospheres. The broad band at 1 μm of asteroid 5641 McCleese is diagnostic of a mineral called olivine, which consists of silicon oxide tetrahedra bound in eightfold symmetry by magnesium, calcium, and iron cations. An instrument will usually have to be calibrated when the measurement conditions are changed, such as when changing from specular included to specular excluded measurements. Uncertainties are also required for establishing the traceability of a measurement to an NMI. The range of wavelengths illuminating the sample is described by the instruments spectral bandwidth or bandpass. The high end of the scale is set by measuring the reflectance factor of a white calibration standard, RW(λ).

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