Topographic LIDAR generally uses a near-infrared laser to map the land, while bathymetric LIDAR uses green light that penetrates the water to also measure the elevations of the seabed and riverbeds. LiDAR is an active remote sensing technique similar to RADAR, but instead of using radio waves as a radiation source, it uses laser pulses. In this technique, a laser source emits pulses that are directed towards the target of interest, such as a landscape of terrain. The pulses reach the ground and part of the laser energy is reflected by a sensor located near the source.
By measuring the round trip time of the emitted laser pulses, the LiDAR system can determine the distance between the sensor and the mapped terrain. The LiDAR can generate a dense, three-dimensional (3D) and georeferenced point cloud, that is. Compared to traditional photogrammetric approaches, LiDAR is less sensitive to the current climate, the time of year, or the time of day during which data is collected. In addition, this technique makes it possible to generate high-resolution 3D topographic information on the surface more quickly due to its ability to penetrate vegetation.
While awaiting the arrival of high-performance photonic lidars, 1550 nm laser diodes can now be used to measure time of flight (ToF) and continuous frequency modulated wave (FMCW) lidars. As an amateur or LIDAR system design engineer, you must consider several factors when selecting a laser source for an automotive LIDAR system.