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UV scale calibration transfer from an improved pyroelectric detector standard to field UV-A meters and 365 nm excitation sources

Published

Author(s)

George P. Eppeldauer, P. Yvonne Barnes, Vyacheslav B. Podobedov

Abstract

Calibration of the emitted radiation from UV sources, peaking at 365 nm, is necessary to perform the ASTM required 1 mW/cm^2 minimum irradiance in certain military material (ships, airplanes etc) tests. These UV "black lights" are applied for crack-recognition using fluorescent liquid penetrant inspection. At present, these nondestructive tests are performed using Hg-lamps. Lack of a proper standard and the different spectral responsivities of the available UV meters cause significant measurement errors even if the same UV-365 source is measured. A pyroelectric radiometer standard with spectrally flat (constant) response in the UV-VIS range has been developed to solve the problem. The response curve of this standard determined from spectral reflectance measurement, is converted into spectral irradiance responsivity with <0.5% (k=2) uncertainty as a result of using an absolute tie point from a Si- trap detector traceable to the primary standard cryogenic radiometer. The flat pyroelectric radiometer standard can be used to perform uniform integrated irradiance measurements from all kinds of UV sources (with different peaks and distributions) without using any source standard. Using this broadband calibration method, yearly spectral calibrations for the reference UV (LED) sources and irradiance meters is not needed. Field UV sources and meters can be calibrated against the pyroelectric radiometer standard for broadband (integrated) irradiance and integrated responsivity. Using the broadband measurement procedure, the UV measurements give uniform results with significantly decreased uncertainties.
Proceedings Title
Advanced Optics for Defense Applications: UV through LWIR II
Volume
10181
Conference Dates
April 9-13, 2017
Conference Location
Anaheim, CA, US
Conference Title
SPIE Defense + Security

Keywords

UV responsivity scale, LED-365 irradiance, broadband UV measurement, integrated radiometric quantities, LED integrated irradiance, UV-LED measurement, flat-response UV meter, pyroelectric UV standard

Citation

Eppeldauer, G. , Barnes, P. and Podobedov, V. (2017), UV scale calibration transfer from an improved pyroelectric detector standard to field UV-A meters and 365 nm excitation sources, Advanced Optics for Defense Applications: UV through LWIR II, Anaheim, CA, US, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=923371 (Accessed July 6, 2022)
Created June 25, 2017, Updated April 7, 2022