Calibration of reflectance standards

Abstract

M easurements of the diffuse spectral reflectance are usually not made as direct measurement of the incident and the reflected r adi ant flux but r ather as measurements relative to a standard of known reflectance value.For the calibration of such standards, different m ethods have been described in the literature :1. Goniophotometric methods, also called Indicatrix methods or point-by-point m ethods. 2. Methods based on the Kubelka-Munk theory. 3. Integr ating sphere methods according to T aylor, Benford, Sharp-Little, van den Akker, Korte. Various materials such as magnesium oxide, barium sulfate or opal glass ar e being used as standards. Their suitability as transfer or as working standards will be discu sed.The r esults of comparative m easurements between some of these methods will be given.

UV reflective properties of magnesium oxide increase attraction and probing behavior of Asian citrus psyllids (Hemiptera: Liviidae)

“…Magnesium oxide and barium sulfate were previously reported as inert compounds with high UV reflective properties [44][45][46][47] . No prior studies have reported how the UV reflective properties of such compounds influence the attraction or probing behaviors of insects.…”

“…Compounds such as magnesium oxide and barium sulfate are highly reflective across the insect and human visual spectra 44 . Magnesium oxide (periclase) is a white, fine powder with high UV reflectance and is used as a reflectance standard 45,46 . It is a divalent oxide that can have surface color centers serving as electron traps following UV exposure; which may explain its UV reflectance 47 .…”

The Role of Scale Adjustment in Color Change Evaluation

“…The CIE recommends the perfect reflecting diffuser as a reference for making measurements of the reflectance factor [15]. A perfect reflecting diffuser is defined as the ideal uniform diffuser with a reflectance equal to unity [16,17]. There is no material that has the properties of a perfect reflecting diffuser; however, through specific techniques and tools, it is possible to calibrate using a white standard representing the ideal uniform diffuser [18].…”

Absolute reflectance of Eastman White Reflectance Standard

“…The output of the photocell was read with an Optronic 730 radiometer readout. The reflectance was calculated from the formula given by Budde,7 (1)…”

“…A modification of the Third Taylor Method, described by Budde,7 was set up for measuring absolute reflectance (Old).…”