LiDAR, which is an acronym for light detection and ranging, is a sensing method that detects objects and maps their distances. This ability to accurately rebuild the 3D surroundings makes it essential for automotive vehicles in the path towards autonomous driving. There are many different system architectures, which can be used to build an automotive LiDAR system. As it is an emerging and very promising technology, a lot of companies try to find the best approach and there are ongoing discussions on the optimal wavelength and illumination principle.
In this paper we will discuss the impact of the system architecture on laser safety calculations. We focus on time-of-flight (ToF) systems, emitting pulsed laser radiation and detecting the reflected return signal. This is currently the most commonly used measurement principle, but there are a lot of system decisions to be made when building a ToF LiDAR system. First, the choice of the wavelength. Here we will discuss 905 nm and 1550 nm regarding their ocular tissue interaction resulting in different limits. Second, the illumination principle can be realized by different scanning methods. Examples are mechanical scanning, semi-solid state scanning, and no scanning, which is often named as solid state. Semi-solid state scanning can be realized by polygon mirrors, MEMS mirrors or Risley prisms. The scanning principle influences the interaction with the eye resulting in different laser safety considerations.
This paper discusses how the choice of the LiDAR architecture is related to laser safety and gives the biological reasoning behind it. Besides this some biased assertions are corrected.