# 17-25-086

aperture

aperture stop

opening that defines the area over which average optical emission is measured

Note 1 to entry: For spectral irradiance measurements, this opening is usually the entrance of a small sphere placed in front of the radiometer/spectroradiometer entrance slit.

Note 2 to entry: This entry was numbered 17-46 and 17-49 in CIE S 017:2011.

Publication date: 2020-12