cie

e-ILV

The e-ILV provides free access to all the terms and definitions contained in the international standard CIE S 017:2020 ILV: International Lighting Vocabulary, 2nd edition.

To search for another term please use  "Back to the list" to return to the main page or the e-ILV.

For the complete set of terms and definitions CIE S 017:2020 can be purchased from the CIE Webshop. Members of a CIE National Committee or Associate National Committee have access to a 66,7 % discount on the purchase price of the standard.

For advice on CIE Publications contact helpdesk@cie.co.at. Note the CIE Helpdesk cannot assist with technical enquiries.

17-24-097

half-value angle, <for a diffusing surface, by reflection or by transmission>

γ

angle of observation at which the luminance has half the value of the luminance of the diffused light at the angle of 0°, with perpendicular incidence of the light

Note 1 to entry: For indicating the shape of the scattering indicatrix it is recommended that the diffusion factor, σ, be used for strongly diffusing materials, and the half-value angle, γ, for poorly diffusing materials.

Note 2 to entry: The half-value angle is expressed in radian (rad) or degree (°).

Note 3 to entry: This entry was numbered 845-04-90 in IEC 60050-845:1987.

Note 4 to entry: This entry was numbered 17-515 in CIE S 017:2011.

Publication date: 2020-12
Copyright © CIE 2020. All Rights Reserverd.