Document ID: chunk:federal_register_of_legislation:F2024C00148:reg:1:p23
Version: federal_register_of_legislation:F2024C00148
Segment Type: reg
Provision Reference: reg 1 (pt 23/34)
Character Range: 198010–201096

the "E" and point in the same direction. The additional symbol shall be directly opposite the approval number. The use of Roman numerals as approval numbers shall be avoided so as to prevent any confusion with other symbols.

Annex 6
Test method for determining reflectivity
              1. Definitions

              1.1. CIE standard illuminate A:[13] Colorimetric illuminate, respecting the full radiator at T68 = 2,855.6 K.

              1.1.2. CIE standard source A1: Gas-filled tungsten filament lamp operating at a correlated colour temperature of T68 = 2,855.6 K.

              1.1.3. CIE 1931 standard colorimetric observer1: Receptor of radiation whose colorimetric characteristics correspond to the spectral tristimulus values (see  table).
              1.1.4. CIE spectral tristimulus values1: Tristimulus values of the spectral components of an equi energy spectrum in the CIE (XYZ) system.

              1.1.5. Photopic vision:1 Vision by the normal eye when it is adapted to levels of luminance of at least several cd/m2.

              2. Apparatus

              2.1. General

              The apparatus shall consist of a light source, a holder for the test sample, a receiver unit with a photodetector and an indicating meter (see Figure 1), and means of eliminating the effects of extraneous light.

              The receiver may incorporate a light-integrating sphere to facilitate measuring the reflectance of non-flat (convex) mirrors (see Figure 2).

              2.2. Spectral characteristics of light source and receiver

              The light source shall consist of a CIE standard source A and associated optics to provide a near-collimated light beam. A voltage stabiliser is recommended in order to maintain a fixed lamp voltage during instrument operation.

              The receiver shall have a photodetector with a spectral response proportional to the photopic luminosity function of the CIE (1931) standard colorimetric observer (see table). Any other combination of illuminate-filter-receptor giving the overall equivalent of CIE standard illuminate A and photopic vision may be used. When an integrating sphere is used in the receiver, the interior surface of the sphere shall be coated with a matt (diffusive) spectrally non-selective white coating.

              2.3. Geometrical conditions

              The angle of the incident beam (Ɵ) should preferably be 0.44 ± 0.09 rad
              (25 ± 5°) from the perpendicular to the test surface and shall not exceed the upper limit of the tolerance (i.e. 0.53 rad or 30°). The axis of the receptor shall make an angle (Ɵ) with this perpendicular equal to that of the incident beam (see Figure 1). The incident beam upon arrival at the test surface shall have a diameter of not less than 13 mm (0.5 inch). The reflected beam shall not be wider than the sensitive area of the photodetector, shall not cover less than 50 per cent of such area, and as nearly as possible shall cover the same area segment as used during instrument calibration.

               When an integrating sphere