High-resolution headlamps: Innovative functionalities and the potential of using laser diodes as light sources

Abstract

High-resolution headlamp systems are increasingly attracting attentions from OEMs and researchers, while plenty of innovative lighting functionalities such as precisely glare avoidance of high beam, fully adaptive driving beam and on-road projection bring a huge potential for improving the driving safety and comfort. Besides, as a respond to the trend of intelligent transportation and autonomous driving in the future, lighting based communication between drivers and other road participants is also a possible supplementary functionality of such headlamp systems. The growth of such headlamps raises specific illumination demands regarding to the functionalities consequently. To achieve these high resolution dynamic light functions and to fulfill the relevant requirements, several additive or subtractive projection technologies are considered by OEMs and researchers. Due to the different applied circumstances and intentions, the uses of these technologies in headlamp systems are different from those in video projectors. Headlamp systems demand a high optical efficiency with highly compact constructions, which raises requirements to the design and arrangement on both mechatronic and optical systems. As a result, particular schemes for different projection technologies have been developing and brought up in recent years. Moreover, the pursuit of efficiency and compaction suggests the appliance of laser diodes as light sources. Laser diodes have intense optical output power with relatively small emission areas and narrow divergent angles, leading to the use of small optical components for realizing compact modules. Besides, other peculiar properties of laser diodes such as linear polarizations and likely fiber-coupled can be utilized for specific designs as well. In this article, the development of headlamp systems in Germany with correspondent innovative functionalities and requirements are discussed, prototypes composed of different technologies are illustrated, and furthermore, the advantages of using laser diodes for these technologies are also presented.