| 摘要 |
A lens includes a medium which absorbs laser radiation that may be harmful to the eye or other high gain optics raising its temperature and thereby changing its index of refraction, adjacent to a medium which does not absorb that radiation thereby providing a spatially fluctuating variation in total phase change, which causes interference and thermal blooming that disperses the radiation sufficiently to lower the intensity at the retinal spot (or optics to be protected) below that which would cause damage. Or, reflective surfaces on absorbing material have the same effect. Volumes which absorb or reflect laser radiation of a given band of frequencies are interspersed with volumes which do not absorb or reflect laser radiation of that given band of frequencies; the second volumes may be non-absorbing and non-reflecting, or may absorb laser radiation of a second band of frequencies. The fluctuation in absorption is small compared to total absorption, thereby to provide elements of radiation having different phases but sufficiently similar intensities. Two (or more) layers of absorbers provide protection from four (or more) bands of frequencies. Lead glass is used, for increased change in index as a function of temperature; and absorbing polycarbonate plastic is used for a lens substrate.
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