Introduction
Signal lights are mainly used to transfer safety message to the maritime transportation users to give specific information (harbour location, hazardous places location...). Aids to navigation lights in maritime navigation transfer this information optically by light signals which have a specific meaning depending on their colour of light and shape.
The usefulness of a marine aid to navigation light greatly depends on the proportion of time for which it may be seen at any required distance, which is called its luminous range. The relationship between luminous range and luminous intensity can be derived from Allard's law, CIE Publ. 17.4., so a full knowledge of the luminous intensity distribution of the light source throughout its zone of utilisation is therefore necessary in order to permit calculation of the limiting range in which the light may just be seen by the mariner for a given meteorological visibility.
The visibility of a maritime signal light depends on the colour, luminous intensity, luminous intensity distribution, luminance of the source, the background luminance, the size of the illuminating area of the signal light and the distance and angle between observer and light signal.
A measurement method for the luminous characterisation of two types of aids to navigation lights (horizon and directional beacons) is specified. Necessary laboratory equipment, measurement principle, measurement plane and co-ordinate system to be chosen, preliminary arragements and sample alignment, testing distance, and angular testing range and intervals are stated depending on the type of signal light. Measurements should be taken at a distance that fulfilled to be greater than the distance of the intersection point and photometric distance.
1 Scope
This standard only applies to horizon beacons and directional beacons, using steady lamps.
The colour of the signal light is not dealt with in this standard. These requirements are specified in IALA 72 (1977).
The described test methods are for indoor (Laboratory) measurements. Outdoor measurements are not covered in this standard.
2 Normative references.
These normative references are cited at the appropriate places in the text and the publications are listed hereafter.
CIE Publ.17.4. (1987) International lighting vocabulary, 4th ed. IEC/CIE
CIE 24.Publ. (1973) .Photometry of indoor type luminaries with tubular fluorescent lamps
CIE 27.Publ. (1973) Photometry of luminaries for street lightning
CIE 43.Publ. (1979) Photometry of floodlights
CIE 53.Publ. (1982) Methods of characterising the performance of radiometers and photometers
CIE 69.Publ. (1987) Methods of characterising illuminance meters and luminance meters:Performance, characteristics and specifications
CIE 70.Publ. (1987) .The measurement of absolute luminous intensity distributions
CIE 84. (1989) Measurement of luminous flux
EN 60598-1. (1993) Luminaires, part 1: General Requirements and Test
IALA 75. (1977) .Recommendations on the determination of the luminous intensity of a marine aid to navigation light
IALA 60. (1974) .Recommendations for the notation of luminous intensity and range of lights
IALA 72. (1977) .Recommendations for the colous of light signals on aids to navigation
