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Solar radiation
Published in Volker Quaschning, Understanding Renewable Energy Systems, 2016
Thermal sensors have a black receiver that heats up in the sun. Two glass domes thermally isolate it. The difference between the receiver’s surface temperature and the ambient temperature is proportional to the irradiance. A thermal element on the back of the receiver converts the temperature difference into a voltage of signal. The benefit of this sensor type is constant spectral sensitivity across a wide range of wavelengths. The sensor is therefore more exact under constant radiance conditions. The drawback is that the sensor has a bit of inertia. Depending on the specific design, it can take up to a minute for the correct final values to be reached. This type of sensor is therefore not suited for quality assurance in the manufacture of solar cells, where measurements are taken with a flash of light.
Color fundamentals for digital imaging
Published in Sharma Gaurav, Digital Color Imaging Handbook, 2017
The stimulus error is often combined with other misuses of color terminology. For instance, one often hears the statement that a prism decomposes white light into its constituent colors. This statement is clearly inaccurate and unacceptable in technical usage. The proper statement would be that a prism decomposes light into its constituent spectral or wavelength components. Spectral power distributions of light, spectral reflectance functions, and spectral sensitivity functions are physical descriptions that are independent of observed sensation, and describing these in terms of color sensations is therefore incomplete and inaccurate. Errors of this type are therefore to be consciously avoided in technical descriptions of color.
Intelligent Robotic Vision Systems
Published in Spyros G. Tzafestas, Intelligent Robotic Systems, 2020
L. Van Gool, P. Wambacq, A. Oosterlinck
Colored lighting can be useful to highlight regions of a similar color. In combination with an appropriate band-pass filter all light but that of a monochromatic light pattern can be attenuated. Diffuse and specular reflection often behave differently with respect to color as well. When colors should be compared as with inspection tasks, the respective light sources must have the same spectral composition. It is also important that the spectral sensitivity function of the sensors be known. A scene may look quite different to a camera than to the human observer.
Photobiology eye safety for horticultural LED lighting: Transmittance performance of eyewear protection using high-irradiant monochromatic LEDs
Published in Journal of Occupational and Environmental Hygiene, 2018
In the current study, the transmitted spectra and corrected irradiance levels for the blanks and samples were acquired using the spectroradiometer and the pyranometer, respectively. Comparing the data measurement sensitivity of the two sensors shows that the pyranometer's spectral response is inadequate to measure narrow spectrum light due to its low spectral sensitivity and its design to measure broad spectrum light (i.e., sunlight). According to the calculation of spectral errors acquired from Eq. 1, the spectral error of the pyranometer was nearly a linear response as the LED wavelength increased, which was similar to the spectral response of the pyranometer. Moreover, we considered spectral errors under the light configuration with shifted spectra (different light spectra with/without glasses) and modified the apparent irradiance levels of the pyranometer through the scaled modification since the effect of low spectral response from the pyranometer was eliminated as the spectra remained the same after filtering. Therefore, the data presented in this study was rectified.