Samenvatting
Most lighting manufacturers represent the angular distribution of the flux of their light sources
by a far-field representation, also known as luminous intensity distribution (LID.) For spatially
extended sources however, the inverse square law is only valid beyond the limiting
photometric distance. By consequence, this distribution does not allow for accurate
illuminances to be determined in the near-field region of the source. This problem is even
more pronounced for arrays of LEDs with focusing optics creating narrow beams. We
gathered a ray-file of several LED arrays using a near-field luminance goniophotometer. This
paper reports on measurements and simulations using ray-tracing. It shows that a far-field
representation cannot be used to calculate illuminance values in the near-field. In contrast, a
near-field representation allows the calculation of accurate illuminance values at any target
point, irrespective of the distance to the source and its luminous intensity distribution.
by a far-field representation, also known as luminous intensity distribution (LID.) For spatially
extended sources however, the inverse square law is only valid beyond the limiting
photometric distance. By consequence, this distribution does not allow for accurate
illuminances to be determined in the near-field region of the source. This problem is even
more pronounced for arrays of LEDs with focusing optics creating narrow beams. We
gathered a ray-file of several LED arrays using a near-field luminance goniophotometer. This
paper reports on measurements and simulations using ray-tracing. It shows that a far-field
representation cannot be used to calculate illuminance values in the near-field. In contrast, a
near-field representation allows the calculation of accurate illuminance values at any target
point, irrespective of the distance to the source and its luminous intensity distribution.
| Originele taal-2 | English |
|---|---|
| Titel | PROCEEDINGS of CIE Expert Symposium on Measurement Uncertainties in Photometry and Radiometry for Industry |
| Pagina's | 60-66 |
| Aantal pagina's | 7 |
| Status | Published - 4 nov 2014 |
| Evenement | CIE Division 2 Expert Symposium on Measurement Uncertainties in Photometry and Radiometry for Industry - Austria, Vienna, Vienna Duur: 9 sep 2014 → 12 sep 2014 |
Seminar
| Seminar | CIE Division 2 Expert Symposium on Measurement Uncertainties in Photometry and Radiometry for Industry |
|---|---|
| Stad | Vienna |
| Periode | 9/09/14 → 12/09/14 |
| Ander | CIE Expert Symposium and Technical Committee Meetings |