Investigation on acquisition of distance information for flash-type LiDAR

Abstract

Distance information is important data that is needed in various industries. Distance information is indispensable in many fields requiring safety and surrounding space information such as autonomous vehicles , automatic target recognition and identification, global environment observation, autonomous planetary landing, and atmospheric analysis. The distance information includes 1D information indicating a distance to a simple object, 2D information indicating a planar shape of the object, and 3D information showing distance information and a planar shape of the object. Among them, 3D information is the most essential information to grasp the surrounding environment. Distance information and 3D information can be obtained through a Light Detection And Ranging (LiDAR) system that obtains distance information through light. LiDAR methods, which have been mainly used to acquire 3D information of an object, include scanning-type and flash-type. Scanning-type LiDAR acquires 3D information by rotating several light sources and light-receiving elements. Because the scanning-type requires rotation, the system becomes bulky and requires additional time to acquire data. Flash-type LiDAR uses a 2D array receiver and expand one light source to an object to obtain 3D information. The data acquisition time is shortened because light is simultaneously irradiated onto the entire area of the object. In addition, rotation is not necessary and volume can be reduced. Therefore, in this paper, we describe three methods of flash-type LiDAR that expands one light source and receives reflected light through a 2D array receiving element, and provides advantages, disadvantages, and utilization guides for each method. Three flash-type LiDAR methods proposed in this paper can be used with 2D array receiving elements to provide 3D information with 1-cm object-to-object distance information. This paper on the methods of using the relationship between polarization and distance, frequency and distance, and frequency mixing will be a good guideline for industries and users who want to obtain 3D information through flash-type LiDAR.