A method of absolute calibration for large aperture optical systems is presented, using the example of the Pierre Auger Observatory fluorescence detectors. A 2.5 m diameter light source illuminated by an ultra--violet light emitting diode is calibrated with an overall uncertainty of 2.1 % at a wavelength of 365 nm.
Cite
@article{arxiv.1305.1329,
title = {Absolute Calibration of a Large-diameter Light Source},
author = {J. T. Brack and R. Cope and A. Dorofeev and B. Gookin and J. L. Harton and Y. Petrov and A. C. Rovero},
journal= {arXiv preprint arXiv:1305.1329},
year = {2015}
}