Laser disability glare with and without a windscreen

Abstract

Purpose: To examine the difference in green laser disability glare with and without an aircraft windscreen. Methods: Gabor patches were presented coincident with, and up to 55 ° eccentric from, a laser glare source. Subjects viewed the Gabor stimuli with their left eye while the right eye was covered and responded whether the Gabor was tilted left or right. The patch subtended 1, 2, 10, and 20 ° and contained 2 1/2; grating cycles at 33% contrast. Two groups of subjects performed the task: one group viewed the laser through an aircraft windscreen, the other group viewed without the windscreen. The laser irradiance levels were from 0.6 microwatts·cm⁻² to 600 microwatts·cm⁻², in 0.5 log steps. A night ambient luminance condition (3 cd·m⁻²), a dawn/dusk ambient condition (30 cd·m⁻²) and a daytime condition (3000 cd·m⁻²) were evaluated. The probability of an error as a function of eccentricity was computed for each condition (laser irradiance X windscreen X target size X ambient level, and the area under this curve calculated for each. Results: Errors increased with laser irradiance; F(2.280, 34.203) = 374.475; p[[lt]] .001, decreased as target size increased; F(1.651, 24.761) = 246.708; p[[lt]] .001. More errors were made with a windscreen than without a windscreen; F(1,15) = 14.229; p = .002., and errors increased as ambient luminance decreased; F(2, 23)= 91.025; p[[lt]] .001. Conclusions: Laser induced disability glare effects are exacerbated by light scatter through an optical media such as an aircraft windscreen, especially for small targets at night. The results can be fitted to the CIE disability glare function, adjusted for the presence of an extraocular scattering element.