Abstract

Radiometric calibration is the process of assigning engineering units and uncertainties to digital counts such that an instrument reading (or image format) conforms to a recognized standard such as radiance. One way to implement spectral radiometric calibration is through the use of an integrating sphere or FEL Lamp/Lambertian plaque setup. Calibrated integrating spheres can be expensive thus in this paper, we (i.e., student and faculty advisor) set out to design, construct, test, and evaluate a NIST-traceable FEL Lamp/plaque setup (as a senior project) for in-house spectral calibration as well as integration into the undergraduate and graduate curriculum at the Center for Imaging Science at the Rochester Institute of Technology. We compared FEL Lamp/plaque spectral radiance measurements to that of a NIST-traceable 20-inch integrating sphere with an uncertainty of 1%. Results showed our set up (with a 1% uncertainty 1000-watt FEL lamp) was on-par with the integrating sphere. As mentioned, this calibration station will be integrated into the lab section of RIT’s radiometry course to educate students on how to conduct spectral radiometric calibration, independent of an integrating sphere. There is much to convey to students from classroom lecture-based radiometric concepts on calibration to the actual use of such a station in the lab. This includes, setting up the source, alignment, operation and usage, measurements, etc. Our take-away is to illustrate how others can replicate our station so as to teach students about hands-on spectral radiometric calibration. We will also discuss our success and failures related to the project. As someone now in the “radiometry” industry, thanks to this project, I would like to like to share our project with the educating community.

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