New direct measurement of high optical attenuation rates in polar bear hairs—2–8 dB/mm in the visible—and reanalysis of the data of Tributsch et al. [ Sol. Energy Mater. 21, 219 (1990)] seem to rule out the UV waveguiding proposed by Grojean et al. [ Appl. Opt. 19, 339 (1980)]. The case against fiber-optic polar bear hairs is summarized, and four conditions are given that any variation of the model of Grojean et al. would have to satisfy.
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