Document ID: chunk:federal_register_of_legislation:F2023C00158:front:0:p3
Version: federal_register_of_legislation:F2023C00158
Segment Type: other
Provision Reference: 
Character Range: 6631–9667

at the time of application for type approval shall apply to this Regulation.

       2.2. "Retroreflection" means the reflection in which light is reflected in directions close to the direction from which it came.  This property is maintained over wide variations of the illumination angle.

       2.3. "Retro-reflecting optical unit" means a combination of optical components producing retroreflection.

       2.4. "Retro-reflecting device" / means an assembly ready for use and comprising one or more retro-reflecting optical units.

       2.5. "Angle of divergence" means the angle between the straight lines connecting the centre of reference to the centre of the receiver and to the centre of the source of illumination.

       2.6. "Illumination angle" means the angle between the axis of reference and the straight line connecting the centre of reference to the centre of the source of illumination.

       2.7. "Angle of rotation" means the angle through which the retro-reflecting device is rotated about its axis of reference starting from one given position.

       2.8. "Angular diameter of the retro-reflecting device" means the angle subtended by the greatest dimension of the visible area of the illuminating surface, either at the centre of the source of illumination or at the centre of the receiver.

       2.9. "Illumination of the retro-reflecting device" is the abbreviated expression used conventionally to designate the illumination measured in a plane perpendicular to the incident rays and passing through the centre of reference.

       2.10. "Coefficient of luminous intensity (CIL)" means the quotient of the luminous intensity reflected in the direction considered, divided by the illumination of the retro-reflecting device for given angles of illumination, divergence and rotation.

       2.11. The symbols and units used in this Regulation are given in annex 1 to this Regulation.

       2.12. A type of "retro-reflecting device" is defined by the models and descriptive literature submitted with the application for approval.  Retro-reflecting devices can be considered as belonging to the same type if they have one or more "retro-reflecting optical units" which are identical with those of the standard model, or if not identical are symmetrical and suitable for mounting one on the left and one on the right side of the vehicle, and if their other parts differ from those of the standard model only in ways not affecting the properties to which this Regulation applies.

       2.13. Retro-reflecting devices are divided into three classes according to their photometric characteristics: Class IA or IB, Class IIIA and Class IVA.

       2.15. Retro-reflecting devices are divided into three classes according to their photometric characteristics: Class IA or IB, Class IIIA and Class IVA.

       2.16. Retro-reflecting devices of Class IB are devices combined with other signal lamps which are not watertight according to annex 8, paragraph 1.1., and which are integrated into the body of