Photometric measurement of goniometer-mounted headlamps involves the detection of light output by a fixed photometer probe positioned at the specified test distance while the headlamp is traversed in the horizontal and vertical planes through a spherical grid of specified magnitude and measurement interval. The present system is capable of a full 360-degree traverse in both planes with the measurement interval adjustable from 0.12 to 1.92 degrees. The scanning grid used for most of the work to date has a total range of 38.4 degrees horizontally and 19.2 degrees vertically, with a 0.48-degree measurement interval. This scan results in a total of 3321 data points and has proven adequate at least for initial headlamp characteristic analysis. In the "hot spot" illumination areas of the SAE headlamps and around the angular cut-off region of the ECE lamps the luminous gradients are very high, thus making precise contour determination difficult. In order to extract more detail, then, a finer scanning grid is obtained by employing a 0.12-degree measuring interval. The data enable very precise comparison of headlamp beams and determination of illumination levels at specified points of interest along the road during field testing by simple application of the inverse square law. /TRRL/

  • Corporate Authors:

    National Research Council of Canada

    1200 Montreal Road
    Ottawa, Ontario  Canada  K1A 0R6
  • Authors:
    • BROWN, R G
    • Gwilt, S R
  • Publication Date: 1974-8-22

Media Info

  • Features: Figures; Tables;
  • Pagination: 35 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00128161
  • Record Type: Publication
  • Source Agency: Road Safety Study and Research Fund, Belgium
  • Report/Paper Numbers: LTR-ST-610 R&D Rept.
  • Files: ITRD, TRIS
  • Created Date: Apr 21 1976 12:00AM