D.4 Measurements
D.4.1 Basic principles
All measurements should be taken in accordance with the basic principles of CIE 121 - 1996.
D.4.2 Planar or line sources
NOTE Reference shall be made to CIE Publication 121, paragraph 6.5. The relatively low luminance values required for EP LLL systems will favor measurements with a luminance meter. The requirement for EP LLL systems does not specify viewing angles and, therefore, measurements may be taken with the photometer viewing the sample perpendicular to the mounting surface.
D.4.2.1 The photohead shall be adjusted to view the largest patch that physical dimensions of the sample will practically allow.
D.4.2.2 Measurements shall be taken at ten different positions along the length of the sample.
D.4.2.3 Compliance shall be checked by ensuring that all values exceed the minimum requirement given in clause 4.3.2.1 of this standard.
D.4.3 Point Sources
NOTE Reference shall be made to CIE Publication 121, paragraph 6.2. The low intensity values required for EP LLL systems will favor absolute measurements calibrated in mcd.
D.4.3.1 The intensity distribution shall be measured in accordance with Cλ. system in 10°λ planes to 80°either side of the long axis and 5°λ planes to 80°either side of the short axis.
D.4.3.2 Compliance shall be checked by ensuring that the mean intensity specified in clause 4.3.2.2 of this standard is achieved from all of the measured angles for miniature incandescent lamps and the minimum peak intensity is available at the center of the cones specified in clause 4.3.2.2.2 of this standard for other point sources.
