Brenda J. Novar

Scaling laser disability glare functions with "K" factors to predict dazzle

With the increasing availability of higher power laser pointers, there is growing coneem about disability glare or dazzle from laser illumination and the safe operation of aireraft and vehicles. A study was condueted to determine the ability of observers to discriminate targets over three log units of laser irradiance (from 0.6 μW·cm−2 to 600 μW·cm−2) and at adaptation levels that simulated twilight (3 cd·m−2), low daytime (30 cd·m−2) and daytime (3,400 cd·m−2) conditions. Other factors that were varied included: target size (0.7°-12°), laser exposure angle (0°-55°), and the presence or absence of an aireraft windscreen. The dazzle effect increased with laser irradiance and decreased as target size increased. The dazzle effect was also greater with a windscreen than without a windscreen, and dazzle increased as ambient luminance decreased. The glare obscuration with eccentricity from the laser source was subsequently used to calibrate the Commission Internationale de l’Eclairage (CIE) disability glare function with appropriate “K” factors, thus allowing a more accurate predietion of dazzle effects across other irradiances and adaptation levels.With the increasing availability of higher power laser pointers, there is growing coneem about disability glare or dazzle from laser illumination and the safe operation of aireraft and vehicles. A study was condueted to determine the ability of observers to discriminate targets over three log units of laser irradiance (from 0.6 μW·cm−2 to 600 μW·cm−2) and at adaptation levels that simulated twilight (3 cd·m−2), low daytime (30 cd·m−2) and daytime (3,400 cd·m−2) conditions. Other factors that were varied included: target size (0.7°-12°), laser exposure angle (0°-55°), and the presence or absence of an aireraft windscreen. The dazzle effect increased with laser irradiance and decreased as target size increased. The dazzle effect was also greater with a windscreen than without a windscreen, and dazzle increased as ambient luminance decreased. The glare obscuration with eccentricity from the laser source was subsequently used to calibrate the Commission Internationale de l’Eclairage (CIE) disability glare fun...

Comparison of violet versus red laser exposures on visual search performance in humans.

Previous research suggests that the visual impairment of a violet laser is not highly localized on the retina, because the lens absorbs most short-wavelength visible light and partly retransmits it as a diffuse fluorescence at approximately 500 nm. The present study investigated whether a 405 nm violet diode laser more greatly impairs visual search performance in humans than does a 670 nm red diode laser, depending on target eccentricity. Participants had to locate a square among 15 diamonds spread throughout a visual search display while being exposed to a violet or red laser beam that was either continuous or flickering and presented either on-axis or 33 degrees off-axis. Whereas the continuous on-axis violet and red lasers had comparable effects on search performance when the target was located near the center of the beam, the violet laser disrupted processing of eccentric targets more than did the red laser. The search decrements were reduced for both lasers when the beams were flickered or presented off-axis. Both the bluish appearance and greater spatial spread of effect of the violet laser suggest that the unique impairment caused by a violet laser beam derives from its induced lens fluorescence.