LiDAR has become a critical requirement for Advanved Driver Assistance Systems (ADAS) as the automotive industry moves towards improved driver safety and autonomous cars. Silicon Photomultipliers (SiPM) and Single Photon Avalanche Diodes (SPAD) sensors are emerging as the most promising sensor technology for long range, >100m, direct time-of-flight LiDAR that needs to function in bright daylight and with low reflectance targets.
SensL is developing a new range of SiPM, the R-Series, that have improved detection efficiency at longer wavelengths used in LiDAR. In parallel to the sensor development, SensL is working to understand the fundamental advantages SiPM and SPAD sensor arrays provide long-range, ADAS LiDAR systems.
It will be shown that to achieve long range LiDAR with eye-safe lasers, a sensor with single photon sensitivity is required. This is due to the low number of returned photons from distances greater than 100m. When ambient daylight conditions are taken into account, the small returned signal at these distances can be easily lost in the noise and histogramming multiple laser pulses will be shown to provide the only method which allows for accurate time of flight ranging operation.
The histogramming technique and the architecture used to implement it will be described. A portable long-range LiDAR demonstrator using SiPM sensors has been developed and will be presented including range accuracy versus distance and low reflective targets. This will be compared to a detailed Monte Carlo model which will be shown to accurately describes SiPM and SPAD array operation in LiDAR ranging.