Climate on Earth is determined by the Earth Radiation Budget (ERB), which quantifies the incoming and outgoing radiative energy fluxes. The ERB can be monitored by non-scanning wide field-of-view radiometers, or by scanning narrow field-of-view radiometers. We propose an enhanced design for the wide field-of-view radiometer, with as key features the use of a near-spherical cavity to obtain a uniform angular sensitivity and the integration of the shuttered electrical substitution principle, eliminating long term drifts of the radiometer and improving its time response. The target absolute accuracy is 1 W/m 2 and the target stability is 0.1 W/m 2 per decade for the measurement of the total outgoing Earth’s radiation. In order to increase the spatial resolution and to separate the total outgoing radiation into reflected Solar and emitted thermal radiation, we propose the joint use of the radiometer with wide field-of-view Shortwave (400–900 nm) and Longwave (8–14 μm) cameras. This paper presents the concept and design of the novel wide field-of-view radiometer, including simulations and analyses of its expected performance. We focus on mechanical design and the measurement characteristics based on optical and thermal analyses. In combination with the cameras, we obtain an estimated accuracy of 0.44 W/m 2 .
The presence of aflatoxins in food and feed products is considered as one of the most important food safety problems in the world. Aflatoxins occur in a wide range of food products and can cause serious health risks. Moreover, they can nowadays only be detected by the use of destructive, time-consuming and expensive chemical analyses. We investigate the use of one-and two-photon induced fluorescence spectroscopy as nondestructive detection methods for the identification of aflatoxins. Particularly, as the samples under test, we consider the aflatoxin-contamination of different maize batches since maize is the staple food in many countries and cultivates in climates that show an extensive presence of the fungi. We first characterize the one-and two-photon induced fluorescence spectrum of pure aflatoxin B1, when excited with 365 nm and 730 nm laser light respectively. Subsequently, we experimentally investigate the fluorescence spectrum of various healthy and aflatoxin-contaminated maize samples, when excited with 365 nm, 405 nm, 730 nm, 750 nm, 780 nm and 810 nm laser light. For all excitation wavelengths, an intrinsic fluorescence signal of the maize grains is observed. However, for the contaminated maize grains, the present aflatoxin B1 significantly influences the intrinsic fluorescence. Depending on the excitation wavelength, we observe a different spectral contrast between the healthy and contaminated samples. The largest optical difference is observed for excitation with 365 nm and 780 nm, during the one-and two-photon induced fluorescence measurements respectively. The comparison of the measured fluorescence signals allows us to define a detection criterion for the optical identification of the contaminated maize samples. We can conclude that fluorescence spectroscopy can be a valuable tool for the measurement of aflatoxin-contents in maize, paving the way for real-time nondestructive industrial scanning-based detection.
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