3 Definitions
Definitions and units used in this Proposal for European Standard come from the International Lighting Vocabulary 4th ed IEC/CIE. CIE Publ. 17.4.
4 Terminology
For the purpose of this European Standard Proposal, the following terminology applies:
4.1 Directional beacon
Aid to navigation signal is normally made up of flat Fresnel lenses. The luminous emission that produces is very directional, with a certain divergence that depends on the designed range, and pulse length if it is a rotational beacon.
4.2 Fresnel lens
Succession of concentric rings, each one consisting of an element of a simple lens, are assembled in proper relationship on a flat surface to provide a short focal length. The Fresnel lens is particularly used in lighthouses and searchlights to concentrate the light into a relatively narrow beam.
4.3 Horizon Beacon
Those which are formed by a cylindrical empty body lens that "envelopes" a lamp in the centre. Their main geometric parameters are cylinder diameter and height. The illumination goes to all directions in a plane, perpendicular to the symmetry axis of the cylinder, located at the filament point (normally at half height of the cylinder).
4.4 Intersection point
The location of the intersection point indicates the distance from which the whole surface of the lens contributes to the illumination of any point on the axis on the optical system.
4.5 Lampchanger
A device which holds the lamp in position and replaces it in case of failure. It usually consists of a lamp turret with a certain lamp capacity and a rotary solenoid which indexes the lamp turret by a spring wound ratchet mechanism.
4.6 Photometric distance
The limiting photometric distance is defined as the minimum distance for which the photometric distance law is fulfilled.
4.7 Zone of utilisation
The zone of utilisation is defined as the assemble of vertical and horizontal directions from the light, within it is intended to be seen from a vessel.
5 General
5.1 Sampling guidelines
The supplier shall provide a fully constructed beacon unit (including housing if necessary).
Units for test shall come complete with any component or devices fitted necessary for the unit.
No repairs, modifications, changes or adjustments of any kind may be carried out among any of the tests to be undertaken. All tests shall be done for the same single unit fitted in.
If there are any alternative lamps or lenses which conform different beacon units, they shall be tested as different and independent samples.
