Abstract
Since laser headlamps are expected to increase distance visibility during night-time driving, we
investigated distance visibility in dynamic conditions and legibility under reflected light on road signs
due to high luminous intensity. We evaluated discomfort glare and the appearance of road-sign colors
due to characteristic spectral distribution of laser headlamps. For their performance of high luminous
intensity, our results assumed an obstacle (20×20 cm and 10% reflectance) on the road and indicated
that its visibility was approximately 1.5 times greater than high-beam lamps using mass-produced LEDs.
We also identified the required upper limit luminance value that ensures road-sign legibility. Regarding
laser headlamp performance of spectral distribution characteristics, discomfort glare was not affected.
Laser headlamps also tend to clarify and sharpen road-sign colors more than other light sources. Our
results suggest that laser headlamps can contribute to night-time traffic safety by improving distance
visibility without focusing on characteristic spectral distribution.
