In order to characterize the light scattered by eye protection filters a reduced luminance coefficient l* = Ls/τE is defined: Ls luminance of scattered light, τ directional transmittance of the filter, E illuminance of incident radiation. The possibilities of measuring this quantity, which is specific for the material concerned [unit (cd/m2)/lx = sr−1] are discussed, and a method is described which also fulfills the ophthalmological conditions; this is demonstrated for filters used in welding. By comparison measurements with an earlier American method, which gives the percentage of the scattered light, it is shown that a value l* = (1 cd/m2)/lx is equivalent to 0.8% scattered light.
© 1968 Optical Society of America
Original Manuscript: September 28, 1967
Published: February 1, 1968
Georg Bauer, Hans-Joachim Hübner, and Ernst Sutter, "Measurement of Light Scattered by Eye Protection Filters," Appl. Opt. 7, 325-329 (1968)