Document ID: chunk:federal_register_of_legislation:F2023L01006:front:0:p7
Version: federal_register_of_legislation:F2023L01006
Segment Type: other
Provision Reference: 
Character Range: 19488–22431

background/surrounding that allows the object to be distinguished from its background/surroundings. The definition is in accordance with the definition given in ISO 9241-302:2008.
         2.1.2.1.2. "Resolution" means the smallest detail that can be discerned with a perceptual system, i.e. perceived as separate from the larger whole. The resolution of the human eye is indicated as "visual acuity".
         2.1.2.1.3. "Visual spectrum" means light with a wavelength within the range of the perceptual limits of the human eyes: 380‑780 nm.
         2.1.2.2. "Close-proximity rear-view mirror" means any device, excluding devices such as periscopes, intended to give a clear view to the rear of the vehicle within the fields of vision defined in paragraph 15.2. by means of a reflective surface.
         2.1.2.2.1. "r" means the average of the radii of curvature measured over the reflecting surface, in accordance with the method described in Annex 7.
         2.1.2.2.2. "The principal radii of curvature at one point on the reflecting surface (ri)" means the values obtained with the apparatus defined in Annex 7, measured on the arc of the reflecting surface passing through the centre of this surface parallel to the segment b, as defined in paragraph 6.1.2.1.2. of this Regulation and on the arc perpendicular to this segment.
         2.1.2.2.3. "The radius of curvature at one point on the reflecting surface (rp)" means the arithmetical average of the principal radii of curvature ri and r'i, i.e.:

         2.1.2.2.4. "Spherical surface" means a surface, which has a constant and equal radius in all directions.
         2.1.2.2.5. "Aspherical surface" means a surface, which has only in one plane a constant radius.
         2.1.2.2.6. "Aspherical mirror" means a mirror composed of a spherical and an aspherical part, in which the transition of the reflecting surface from the spherical to the aspherical part has to be marked. The curvature of the main axis of the mirror is defined in the x/y coordinate system defined by the radius of the spherical primary calotte with:
         Where:
         R: nominal radius in the spherical part
         k: constant for the change of curvature
         a: constant for the spherical size of the spherical primary calotte
         2.1.2.2.7. "Centre of the reflecting surface" means the centre of the visible area of the reflecting surface.
         2.1.2.2.8. "The radius of curvature of the constituent parts of the mirror" means the radius "c" of the arc of the circle which most closely approximates to the curved form of the part in question.
         2.1.2.3. "Other devices for means of rear visibility" means devices as defined in paragraph 2.1.2. above, where the field of vision is not obtained by means of a mirror or a Rear-View Camera System.
              2.1.3. "Test object" means a cylindrical object with a height of 0.8 m and a diameter of 0.30 m.

         2.1.4.