The difference between radar and laser radar

The difference between radar and laser radar is evident in the following aspects:

Principle of operation and signal carrier
Traditional radars use radio waves (electromagnetic waves in the microwave range), emitting electromagnetic signals, receiving echo signals reflected from the target, and calculating the position and speed of the target using time difference, Doppler shift, etc. Laser radar uses a laser beam (visible light or infrared light), emitting narrow laser pulses, and calculates the distance using precise time measurement, as well as using a scanning mechanism to generate a three-dimensional point cloud, providing detailed information about the shape and distance to the target.

Performance and accuracy
In terms of resolution, traditional radar is inferior to laser radar because its wavelength is longer, making it difficult to capture details; laser radar has a very high resolution, reaching the centimeter level, and can distinguish the contours of small targets. In terms of detection range, traditional radar has a long range, reaching hundreds of kilometers, and is suitable for remote tracking; laser radar has a medium to short range, from hundreds of meters to several kilometers, and is focused on high-precision detection at close range. In terms of adaptability to the environment, traditional radar is highly dependent on atmospheric humidity and precipitation; laser radar is less dependent on weather conditions, but its performance is slightly reduced in rainy, snowy, and foggy weather. In terms of interference resistance, traditional radar is weaker, as it is susceptible to interference from scattered echo signals; laser radar is stronger, as the laser beam is highly directional and the multipath effect is small.

Areas of application
Traditional radar is mainly used in the military, aviation, meteorology (e.g., for weather forecasting), ocean monitoring, etc., and is focused on tracking distant targets and detection at long ranges. Laser radar is more commonly used in autonomous driving, unmanned aerial vehicles, robotics, geological surveying, etc., with an emphasis on high-precision 3D modeling and perception of the immediate environment.

Cost and development trends
Traditional radar technology is mature, inexpensive, and widely available. Laser radar was initially expensive, but in recent years its cost has gradually decreased thanks to technological advances, and it has become the primary sensor in areas such as autonomous driving.

Overall, the main difference between them is the signal carrier, and in practical applications, they are often used together, complementing each other.

-Why does laser radar have blind spots?

The problem of blind spots in laser radar is related to the dead zone time of its receiver. The dead zone time is usually between a few and several tens of nanoseconds and represents the minimum time between the reception of one laser pulse by the laser radar and the possibility of receiving the next new laser pulse. This leads to inaccuracies in distance measurement when the laser radar processes objects at close range, and this phenomenon is called “point absorption.” The pulse echo signal from objects located at close range cannot be effectively detected when the laser receiver is in the dead zone, which affects the accuracy of distance measurement.
The problem of “point absorption” is one of the most difficult in the field of laser radar and requires constant improvement and optimization of equipment to reduce the size of the blind zone. The size of the blind spot varies depending on the product and is typically between 0.1 and 2 meters. In practical applications, laser radar must be able to accurately detect obstacles in this zone to avoid collisions and other dangerous situations.
To solve the problem of blind spots, laser radar technology is constantly evolving and improving. For example, by optimizing the mechanism of laser radiation emission and reception, the dead zone time is reduced, detection sensitivity is increased, and more sophisticated algorithms are used to improve the ability to recognize objects at close range. In addition, developers are exploring methods such as using a combination of multi-beam laser radars and increasing the number of sensors to expand the effective detection zone and further reduce blind spots.
With the continuous advancement of laser radar technology and the expansion of its application scope, solving the blind spot problem will contribute to improving the safety and reliability of devices such as autonomous vehicles, drones, and robots. In the future, thanks to continuous technical innovation and optimization, laser radar is expected to play an important role in broader scenarios, bringing more convenience and safety to people's lives and production.

-What are the functions of laser radar? How accurate is laser radar?

The functions of laser radar mainly include high-precision electronic mapping and positioning, obstacle recognition, passable space determination, and obstacle trajectory prediction. The accuracy of laser radar can reach the centimeter level.

High-precision electronic mapping and positioning: by combining point cloud information collected by multi-beam laser radar with data from the onboard inertial navigation system, a high-precision map is created, enabling high-precision navigation of unmanned vehicles.
Obstacle recognition: After determining the area of interest, the laser radar can analyze the characteristics of obstacles and use recognition algorithms to detect and identify obstacles, which is crucial for the safe movement of autonomous vehicles.
Passable space detection: Based on high-precision electronic maps, the passability of a given area is determined by analyzing the height and continuity of the point cloud within the area of interest, which helps the autonomous vehicle understand its surroundings and make intelligent decisions while driving.
Predicting the trajectory of obstacles: Based on laser radar data and the topological relationships between the lanes where obstacles are located, the trajectory of obstacles is predicted, which is important for planning the route of autonomous vehicles, especially during maneuvers such as obstacle avoidance, lane changes, and overtaking.
Laser radar accuracy: As an active measurement device, laser radar provides centimeter-level positioning accuracy, making it extremely valuable for use in high-level autonomous driving. Its high accuracy and powerful environmental perception capabilities ensure the safety and efficiency of autonomous vehicles.