Detailed Types of LiDAR: How Many Do You Know?

LiDAR (Light Detection and Ranging) integrates laser, GPS (Global Positioning System), and an IMU (Inertial Measurement Unit) into a sensing system. Compared with conventional radar, LiDAR typically offers higher resolution, better concealment, and stronger anti-interference capability. As technology continues to advance, LiDAR has become increasingly widespread across robotics, autonomous driving, unmanned vehicles, and many other domains. As demand grows, LiDAR products have diversified rapidly. Depending on function, detection method, and deployment platform, LiDAR can be classified into multiple types.

(LiDAR type diagram)

Classification by Function

1) Laser Ranging LiDAR

Laser ranging LiDAR emits a laser beam toward a target, receives the reflected return, and computes distance based on the measured time difference. Traditionally, it has been used in industrial safety applications—for example, “laser wall” intrusion detection systems. It is also widely applied in surveying and mapping.

With the rise of AI-driven robotics, laser ranging LiDAR has become a core component in many robot platforms. When combined with SLAM, it enables real-time localization and navigation for autonomous movement. SLAMTEC’s RPLIDAR series, when used with SLAMWARE modules, is a representative solution in service-robot navigation: within a 25 m range radius, it can perform tens of thousands of ranging measurements per second with millimeter-level resolution.

2) Laser Speed (Velocity) LiDAR

Velocity LiDAR measures the speed of a moving object. A basic approach is to perform two range measurements separated by a known time interval and compute velocity from distance change over time.

There are two primary methods:

• Range-difference method (time-separated ranging):Continuously measure target distance at a fixed interval; velocity is the distance difference divided by the time interval. Direction is determined by the sign of the distance change. The system is structurally simple but offers limited accuracy and generally requires strong reflectivity targets (hard objects).
• Doppler frequency shift method:When there is relative motion between LiDAR and target, the frequency of the received echo differs from the transmitted signal. The resulting frequency difference is the Doppler shift, which can be used to estimate radial velocity.

3) Atmospheric Sensing LiDAR

Atmospheric LiDAR is used to measure molecular density, smoke/aerosol concentration, temperature, wind speed and direction, and water vapor content. These measurements support environmental monitoring and forecasting of hazardous weather such as storms and dust events.

 4) Laser Imaging LiDAR

Imaging LiDAR can detect and track targets, providing bearing and velocity information. It can perform tasks beyond conventional radar, such as detecting submarines, underwater mines, and concealed military targets. It is widely used in defense, aerospace, industry, and medical applications.

5) Tracking LiDAR

Tracking LiDAR continuously tracks a target and measures its coordinates to provide motion trajectories. Applications include artillery control, missile guidance, external ballistics measurement, satellite tracking, penetration research, and expanding use in meteorology, transportation, and scientific research.

Classification by Laser Medium

1) Solid-State LiDAR

Solid-state LiDAR provides high peak power and operates at wavelengths compatible with existing optical components (e.g., modulators, isolators, detectors) and atmospheric transmission characteristics. It can readily implement MOPA (Master Oscillator Power Amplifier) architectures and offers high efficiency, compact size, low weight, high reliability, and good stability—making it preferred for airborne and spaceborne systems. In recent years, diode-pumped solid-state LiDAR has become a major development focus.

2) Gas Laser LiDAR

Gas laser LiDAR is represented by CO₂ LiDAR, operating in the infrared band with low atmospheric attenuation and long detection range. It has proven valuable for atmospheric wind field and environmental monitoring. However, the systems are often bulky, and mid-infrared HgCdTe detectors typically require operation at 77 K, limiting broader development.

3) Semiconductor LiDAR

Semiconductor LiDAR supports high repetition-rate continuous operation and offers long lifespan, small size, low cost, and reduced eye safety risk. It is widely used in strong backscatter applications such as Mie-scattering measurements (e.g., cloud base height detection). Potential applications include visibility measurement, aerosol extinction profiles in the atmospheric boundary layer, and precipitation identification. A representative example is Vaisala’s CT25K ceilometer, with a maximum cloud-base measurement range of 7,500 m.

Classification by Number of Scan Lines

1) Single-Line LiDAR

Single-line LiDAR is mainly used for obstacle avoidance. It provides fast scanning, strong resolution, and high reliability. Because it can respond quickly in angular frequency and sensitivity compared to multi-line/3D LiDAR, it can deliver high accuracy in measuring obstacle distance. However, single-line LiDAR performs planar scanning only and cannot directly measure object height, which limits its use. It is widely deployed in service robots such as vacuum cleaning robots.

2) Multi-Line LiDAR

Multi-line LiDAR is commonly used for automotive LiDAR imaging. Compared with single-line LiDAR, it enables significantly improved scene reconstruction and can capture height information. Multi-line systems are often referred to as 2.5D, with some reaching 3D capability. Typical offerings include 4-, 8-, 16-, 32-, and 64-line models. Due to high cost, many automakers avoid these configurations in mass production.

Classification by Scanning Method

1) MEMS LiDAR

MEMS LiDAR can dynamically adjust scanning patterns to focus on specific targets, enabling detection and identification of small or distant objects—capabilities not easily achieved with traditional mechanical LiDAR. A MEMS system uses a small mirror to steer a fixed laser beam across directions. Due to low inertia, the mirror can move rapidly, enabling 2D scanning modes within sub-second response times.

2) Flash LiDAR

Flash LiDAR captures an entire scene quickly, reducing issues caused by motion during scanning and operating similarly to a camera. A single flash illuminates the scene, and a micro-sensor array captures returns from multiple directions. While it offers speed and simplicity, it also has limitations: higher pixel counts require processing larger signal volumes, and dense integration can introduce interference, reducing accuracy.

3) Phased-Array LiDAR

Phased-array LiDAR uses an array of emitters and steers the beam by adjusting relative signal phase. At present, most phased-array LiDAR remains in laboratory research, while commercial systems are still dominated by rotating mechanical and MEMS-based solutions.

 4) Mechanical Rotating LiDAR

Mechanical rotating LiDAR is the earliest and one of the most mature architectures. However, it is mechanically complex and expensive, typically consisting of lasers, scanners, optical components, photodetectors, receiver ICs, and positioning/navigation components. High hardware cost makes mass production difficult, and long-term stability can be a concern. As a result, many companies are shifting focus toward solid-state LiDAR.

Classification by Detection Method

1) Direct-Detection LiDAR

Direct-detection LiDAR has a structure similar to a laser rangefinder. The transmitter emits a signal, the target reflects it, and the receiver collects the return. Distance is obtained by measuring round-trip propagation time. Radial velocity can be derived from Doppler shift of the reflected light or by measuring multiple distances over time and computing the rate of change.

2) Coherent-Detection LiDAR

Coherent LiDAR can be monostatic or bistatic. In monostatic systems, transmit and receive share the same optical aperture and are isolated via a transmit/receive switch. Bistatic systems use separate apertures for transmit and receive, eliminating the need for a T/R switch; other subsystems are similar.

Classification by Laser Emission Waveform

1) Continuous-Wave (CW) LiDAR

Continuous-wave LiDAR emits light continuously (similar to a flashlight being switched on). Data acquisition is performed continuously at a given range/altitude, but at any moment it effectively samples a single point. For wind measurement, representing conditions at a height using only a single point can be insufficient. A common workaround is to rotate 360° and average measurements across multiple points on a circle—effectively multi-point statistics on a virtual plane.

2) Pulsed LiDAR

Pulsed LiDAR emits bursts rather than continuous light. By transmitting many pulses and analyzing their reflections (often using Doppler principles), it can estimate wind conditions at a given altitude in a more volumetric manner, supporting a defined sensing range. Compared with CW LiDAR, pulsed LiDAR provides many more measurement points and can represent wind profiles more accurately.

Classification by Deployment Platform

1) Airborne LiDAR

Airborne LiDAR tightly integrates laser ranging, GNSS, and INS, using an aircraft as the carrier. By scanning the ground and recording attitude, position, and reflectivity intensity, it generates 3D surface information and derived spatial products. It has strong potential in both civil and defense domains. However, due to atmospheric attenuation, effective range is typically within 20 km, and performance degrades significantly under fog, heavy rain, smoke, or dust. Atmospheric turbulence can also reduce measurement accuracy.

2) Vehicle-Mounted LiDAR

Vehicle-mounted LiDAR (mobile 3D laser scanning) emits and receives laser beams, calculates relative distance from return time, and reconstructs 3D models using dense point coordinates and reflectivity data. It enables rapid 3D point cloud generation and environment mapping for perception. In the autonomous driving ecosystem, its importance continues to increase. Companies such as Google, Baidu, BMW, Bosch, and Delphi have adopted LiDAR in autonomous driving systems, accelerating the growth of the automotive LiDAR sector.

3) Terrestrial (Ground-Based) LiDAR

Terrestrial LiDAR captures 3D point clouds in forested environments and supports extraction of individual tree positions and heights. It reduces labor and cost while improving accuracy, offering advantages over many other remote sensing methods. Future work is expected to expand this approach to larger study areas and broader forest parameter extraction.

4) Spaceborne LiDAR

Spaceborne LiDAR uses satellites with high orbits and wide observation coverage, enabling global access. It provides new methods for obtaining 3D control points and digital terrain models in overseas regions, with significant value for defense and scientific research. Spaceborne LiDAR can also support lunar and Mars exploration by generating comprehensive 3D topographic maps. Additional applications include measuring vertical vegetation structure, sea surface height, cloud/aerosol vertical distribution, and monitoring special climate phenomena.

Conclusion

With the above overview of LiDAR characteristics, principles, and application domains, readers can better understand the differences among LiDAR types. Today, competition in LiDAR is intensifying, and many startups aim to develop low-cost, mass-producible LiDAR products. However, LiDAR development and production at scale remain challenging. Only organizations with deep industry experience and reliable engineering capabilities are likely to maintain leadership in this wave of growth.