| 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, which causes a phase change in the radiation passing therethrough. The medium may be periodically bounded by thermal sinks, thereby providing a periodic differential in temperature rise, may be provided in a length which varies periodically or may have a density of absorbing material which varies periodically, thereby to have a periodic absorption characteristic. The periodicity, which may be regular or random, provides a periodic variation in total phase change, which causes interference (thermal blooming) that disperses the radiation sufficiently to lower the intensity at the retinal spot below that which would cause damage. Eyeglasses with mutually perpendicular periodicity provide degraded vision of useful images while being protected from harmful radiation.
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