A Solid-State Irradiance Calibrator for Field Use

70813 Expanding our understanding of climate change will require more accurate measurements of solar radiation. Although the frequent calibration of radiometers is essential for accurate data collection, it is not practical to send field instruments to a calibration facility. A solid state irradiance source would provide the robustness and stability required for field calibration. This project will assess the performance of light emitting diodes (LEDs) for this purpose by testing their stability over time and temperature. The novel concept of spectral shaping will be investigated. The design of the irradiance calibrator will then be tailored to take advantage of these particular characteristics. Phase I will extensively characterize LEDs to test stability and spectral output. Theoretical and data based models of LED output will be built to assess the feasibility of shaping the spectral output to match the solar spectrum and to determine the best configuration for a solid-state calibrator. Commercial Applications and Other Benefits as described by the awardee: The irradiance calibrator should find use by the DOE and other governmental agencies to increase the accuracy of field measurement of solar radiation. Other uses include the calibration of other optical devices such as digital cameras.