| 摘要 |
The invention relates to a beacon lamp which includes a point source of light located at F and surrounded by a transparent cap (20) which is in the shape of a solid of revolution about an axis zz' which passes through F and which forms at least one annular lens (L1, L2) whose focus is F. The profiles of the optical surfaces of the lens(es) are such that they produce a cap which can easily be moulded and which is anastigmatic for the point F and infinity, i.e. which concentrates much of the light from the point F into a plane (25) through the point F. Application to lamps for indicating the survivors at sea of shipwrecks or air crashes, said lamp being suitable for equipping life jackets on board aircraft. |
