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Spectroradiometers are devices designed to measure the spectral power distribution of a source. From the spectral power distribution, the radiometric, photometric, and colorimetric quantities of light can be determined in order to measure, characterize, and calibrate light sources for various applications. Spectroradiometers typically take measurements of spectral irradiance and spectral radiance. This spectral data can be used to calculate CIE tristimulus values through mathematical integration. CIE chromaticity coordinates and luminosity can then be calculated, providing a complete description of the source’s color, including chromaticity, spectral power, illuminance, and luminance.〔IES, Illuminating Engineering Society. Lighting Measurements: A Basic Approach to Understanding the Principals of Lighting Science. Handour. Comp. Nlena and Associates, Inc. Retrieved from http://www.ies.org/pdf/education/IES-Color-3-Webcast-Handout.pdf〕 Spectroradiometers are stand-alone systems that work independently without the need to be connected to a PC. This makes them highly portable while maintaining the accuracy of a spectrometer.〔http://sensing.konicaminolta.us/2013/11/what-is-the-difference-between-radiometers-spectrometers-and-spectroradiometers/〕 ==Background== The field of spectroradiometry concerns itself with the measurement of absolute radiometric quantities in narrow wavelength intervals.〔Leslie D. Stroebel and Richard D. Zakia (1993). Focal Encyclopedia of Photography (3rd ed. ed.). Focal Press. p. 115. ISBN 0-240-51417-3〕 It is useful to sample the spectrum with narrow bandwidth and wavelength increments because many sources have line structures 〔Berns, Roy S. "Precision and Accuracy Measurements." Billmeyer and Saltzman's Principles of Color Technology. 3rd ed. New York: John Wiley & Sons, 2000. 97-100. Print〕 Most often in spectroradiometry, spectral irradiance is the desired measurement. In practice, the average spectral irradiance is measured, shown mathematically as the approximation: : Where is the spectral irradiance, is the radiant flux of the source (SI unit: watt, W) within a wavelength interval (SI unit: meter, m), incident on the surface area, (SI unit: square meter,m²). The SI unit for spectral irradiance is W/m3. However it is often more useful to measure area in terms of centimeters and wavelength in nanometers, thus submultiples of the SI units of spectral irradiance will be used, for example μW/cm2 *nm〔 Spectral irradiance will vary from point to point on the surface in general. In practice, it is important note how radiant flux varies with direction, the size of the solid angle subtended by the source at each point on the surface, and the orientation of the surface. Given these considerations, it is often more prudent to use a more rigorous form of the equation to account for these dependencies〔Kostkowski, Henry J. Reliable Spectroradiometry. La Plata, MD: Spectroradiometry Consulting, 1997. Print.〕 Note that the prefix “spectral” is to be understood as an abbreviation of the phrase “spectral concentration of” which is understood and defined by the CIE as the “quotient of the radiometric quantity taken over an infinitesimal range on either side of a given wavelength, by the range”.〔Sanders, Charles L., and R. Rotter. The Spectroradiometric Measurement of Light Sources. Paris, France: Bureau Central De La CIE, 1984. Print.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Spectroradiometer」の詳細全文を読む スポンサード リンク
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