| 摘要 |
A limited visibility signal device is disclosed which includes a housing, a source of illumination within the housing, a light directing lens at the outer end of the housing, and a light collimating arrangement between the source of illumination and light directing lens to intensify and directionally control light delivered to the light directing lens. The light directing lens includes an inner side provided with parallel lenticular elements extending thereacross and having first outer surface portions parallel to the lens axis and second outer surface portions of circular contour. The light directing lens further includes an outer side provided with parallel adjacent lenticular elements extending thereacross perpendicular to the elements on the inner side of the lens and alternate ones of which are of convex and concave contour with respect to the lens axis. The device emits light in a pattern defining a longitudinal section of a cone which includes a plane of light parallel to the lens axis and laterally outwardly of which the emitted light from the device is not visible. Preferably, light collimation is provided by a Fresnel lens within the housing adjacent the light directing lens.
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