# Evaluation and Testing System for Automotive LiDAR Sensors
## 2 LiDAR Sensors for Automotive  
As a high-level overview, a LiDAR system is composed of two main components: an emitter (laser) and a receiver (light detector), as depicted in Figure 2. The laser emits short pulses of light with a well-defined time interval (a few to several hundred nanoseconds) and with specific spectral properties into the optical steering system. By regulating the mirror's angle, the system controls the direction of the light vertically and horizontally, providing multiple angle detection with just a single beam. Additionally, the optical properties of the beam can be changed by the lens system in order to achieve better performance ratios, e.g., by adding signal modulation schemes [23; 34]. When the transmitted light hits an object, the backscattered signal is collected by the receiver, which can filter and select specific wavelengths or polarization schemes. In addition, the receiver system is responsible for converting the optical signal into an electrical representation and storing it along with its intensity values in a computing unit. Moreover, the receiver calculates the time of travel of the transmitted light to obtain the distance to the obstacle. Within an automotive application, the main characteristics of a LiDAR sensor that need to be considered for inclusion in a LiDAR testing and evaluation platform are: (1) the horizontal and vertical field of view (FoV); (2) the horizontal and vertical angular resolution (AR); (3) the influence of external illumination; (4) power consumption; and (5) the sensor's minimum and maximum ranges. The aforementioned parameters are described in detail below:  
* The **Field of View** is one of the metrics that defines the maximum angle at which a LiDAR sensor is able to detect objects, as shown in Figure 3. When two scanning angles are available, the sensor can scan a 3D area defined by the Vertical FoV (VFoV) and the Horizontal FoV (HFoV). This test is designed to identify the maximum detection angles of the sensor in order to validate its defined values. * The **Angular Resolution** represents the sensor's ability to scan and detect objects within the FoV, as depicted in Figure 4. Higher resolutions allow for smaller blind spots between laser firings, enabling the detection of small objects and greater detail of the environment, particularly at higher detection ranges. Thus, this test is designed to identify the angular resolution both vertically and horizontally in different areas of the FoV in order to verifying that the collected values match the requirements and/or the sensor's characteristics as defined by the manufacturer. Figure 2: LiDAR working principle. * **Background Light and Sunlight** can have a severe impact on sensor behaviour. In real-world environments, LiDAR sensors may experience substantially decreased performance when exposed to external light interference, such as sunlight backscattering from targets with high reflectivity characteristics. Removing such light noise can be particularly challenging, as solar radiation is a powerful light source present in a wide range of wavelengths [35]. Therefore, it is important to evaluate sensor output when exposed to background light in a controlled environment. * The **Power Consumption** test aims to monitor and analyze the power consumption of the sensor under test in different operation modes, configured parameters, and environment/target conditions. * The **Range** can be defined as the minimum and the maximum distances at which the sensor successfully detects an object. While detecting the minimum range can be quite simple, finding the maximum range is not straightforward, and depends on the target's reflectivity, which is considered detected when it appears in at least 90% (detection probability) of the the sensor's data output. With a target reflectivity higher than 40-50%, detecting the maximum range in a straight line inside our testing laboratory (maximum range 100 m) would be impossible for high-range sensors.