| 摘要 |
Optical elements for vessel navigation lights, providing improved and inexpensive means for achieving uniform, luminous intensity over a sharply bounded horizontal arc of visibility, and also for achieving a desired vertical arc of visibility, comprise means for projecting light from a diffuse source or an array or mosaic of point sources into a field the horizontal and vertical arcs of which can be precisely defined. The disclosure encompasses two geometric configurations for projecting light, symmetrical and asymmetrical, compound parabolic concentrators, each of which may be constructed as either a reflective cavity or a refractive dielectric, thereby to provide four basic designs for achieving uniform illumination over various horizontal arcs of visibility. In addition, the disclosure encompasses three modes of diffuse light projection to achieve uniform illumination over various vertical arcs of visibility. Due to the precision of the results obtained, the optical elements provide navigation lights fully in compliance with the rigid specifications for arcs of visibility set forth in the Final Act of the International Conference on Revision of the International Regulations for Preventing Collisions at Sea, 1972 (72 COLREGS) and the International Rules of Navigation Act of 1977, 33 U.S.C. 1601, and do so with particular economy.
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