Abstract: A top assembly which comprises a cover assembly having a circular shape with a flat surface and having apertures for securement on top of the light base, said cover assembly having at least one window fitted with optical prism or lens means for the passage of each output light beam from an optical system, and further having a draining aperture in front of each said window; and at least one light channel plate to be mounted adjacent the cover assembly in coaxial alignment with the optical axis of the apparatus, said channel plate having an elongated shape with circular arcuate end sides, the curvature of a first of said end sides mating with the curvature of the peripheral edge of the cover assembly so as to be placed adjacent said peripheral edge. The cover assembly has cover inner means secured to the underside of it to form with said cover assembly a water-tight enclosure for the optical system.