@article{ref1,
title="Spherical lens optics applied to retrodirective reflection",
journal="Highway Research Board bulletin",
year="1952",
author="Havens, James H. and Peed, Allie C.",
volume="56",
number="",
pages="66-77",
abstract="This paper describes some expedient applications of elementary optical principles to the evaluation of glass-bead reflectorizing systems for highway signs and markers. The optical function of spherical lenses in achieving reflex reflection is illustrated both photographically and diagrammatically. Various optical designs are discussed and analyzed. By simple geometric optics, the efficiency of these systems is correlated with the practical performance criteria for retrodirective reflectorization.<p />",
language="en",
issn="0073-2206",
doi="",
url="http://dx.doi.org/"
}