Wavelength and ambient luminance dependence of laser eye dazzle

Abstract

A series of experiments has been conducted to quantify the effects of laser wavelength and ambient luminance on the severity of laser eye dazzle experienced by human subjects. Eight laser wavelengths in the visible spectrum were used (458-647 nm) across a wide range of ambient luminance conditions (0.1-10,000 cd·m). Subjects were exposed to laser irradiance levels up to 600 μW·cm and were asked to recognize the orientation of optotypes at varying eccentricities up to 31.6 deg of visual angle from the laser axis. More than 40,000 data points were collected from 14 subjects (ages 23-64), and these were consolidated into a series of obscuration angles for comparison to a theoretical model of laser eye dazzle. Scaling functions were derived to allow the model to predict the effects of laser dazzle on vision more accurately by including the effects of ambient luminance and laser wavelength. The updated model provides an improved match to observed laser eye dazzle effects across the full range of conditions assessed. The resulting model will find use in a variety of laser safety applications, including the estimation of maximum dazzle exposure and nominal ocular dazzle distance values.

Determination of a laser eye dazzle safety framework

“…As with the main experiment that validates this work, 8,13 the authors have made available the complete data and analysis from this paper to encourage independent verification of the methodology. 14 A spreadsheet calculator has also been published 17 to facilitate calculation of MDE and NODD values for specific scenarios, together with optical density requirements for laser eye protection.…”

“…Detecting a 0.08°object is approximately equivalent to detecting a 5 m long car at a range of 3.5 km or a 0.5 m human torso at 350 m. Table II populates the MDE table with values from the human subject experiments, as well as from the updated computer model. Experimental data from the authors' earlier work 8,13 were averaged across all laser wavelengths (up to eight) for each relevant combination of ambient luminance and object size, with the photopic luminous efficiency being factored out of the calculations. The experimental irradiance ranges given are the average value plus and minus one standard deviation, with footnote "a" denoting values that were extrapolated beyond the irradiance levels used in the actual experiment.…”

Laser dazzling in the visible region: some issues

“…Laser dazzling is recently studied within a NATO group involving both modelling [3,4,5] and experiments in laser dazzling and its effect on different task performance [6,7,8] as well as protection against dazzling [9,10]. While laser dazzling against CCD/CMOS cameras, image intensifiers and IR cameras does not in general involve ethical considerations, eye dazzle will often be limited by eye safety demands and ethical aspects.…”

Use of complementary wavelength bands for laser dazzle protection

“…1 Recently, a lot of work was done on the investigation of laser eye dazzle, [2][3][4] including the impact of windscreens on the dazzle effect. 5 Regarding laser safety of the human eye, the concepts of maximum dazzle exposure and nominal ocular dazzle distance (NODD) were proposed [6][7][8] as an extension of the established quantities, maximum permissible exposure, and nominal ocular hazard distance. Moreover, in order to evaluate the influence of optical nuisance, tests on human performance degradation under laser dazzle were carried out.…”