LiDAR vs LADAR: Key Differences Explained

Introduction

In the world of remote sensing and navigation technologies, LiDAR (Light Detection and Ranging) and LADAR (Laser Detection and Ranging) are two popular terms often used interchangeably. While both technologies leverage laser beams for detection and measurement, they differ in their specific applications and working principles. In this guide, we will break down the key differences between LiDAR and LADAR, discuss their unique advantages, and help you determine which is best suited for your needs.

What is LADAR?

LADAR uses 3 semiconductor diodes to generate laser light. It uses light pulses to make two consecutive distance measurements, then divides by time. Lenses are utilized to collimate light to a narrow beam. Typically, ANSI Class-I laser devices are used. The laser radar consists of a laser, receiver, and clock. It has a larger aperture gain and larger bandwidth. Hence, very accurate measurements can be performed. A LIDAR receiver antenna is usually not shared with the transmitter part. The receiver antenna focuses incoming radiated waves to a point size. As we know, EM energy at high frequencies is referred to as photons or quanta.

LiDAR RCS Formula

LiDAR operates on the principle of an envelope detection system, which is incoherent. The RCS (Radar Cross Section) of LiDAR is expressed by the following equation:

RCS of laser radar, $\sigma_l = \rho * \frac{4 \pi A^2}{\lambda^2}$

Where:

• $\rho$ is the reflectivity of the target
• $A$ is the effective intercepting area of the object or target
• $\lambda$ is the wavelength of the laser

Figure depicts a LiDAR or LADAR system.

This UPC Backscatter LiDAR has the following specifications:

LASER PART:

• Energy: 0.5 J/532 nm
• Divergence: 0.1 mrad
• Pulse length: 10 ns
• PRF: 10 Hz

RECEIVER PART:

• Focal length: 2 m
• Aperture φ : 20 cm
• Detector: APD
• Bandwidth: 10 MHz

SYSTEM SPECS:

• Configuration: vertical biaxial
• Acquisition: 20 MSPS/12 bit
• Spatial resolution: 7.5 m
• Min. det. power < 5 nW

LiDAR Classification

LiDAR can be classified based on their application or configuration:

Based on their APPLICATION:

• ELASTIC-BACKSCATTER LIDAR
• WIND LIDAR (Doppler lidar)
• SPECTROSCOPIC LIDAR

Based on their CONFIGURATION:

• MONO-STATIC LIDAR: Backscatter, DIAL, Raman, Doppler, Fluorescence etc.
• BI-STATIC LIDAR: Long path absorption Airborne (plane, helicopter, satellite), mobile, ground based etc.

Advantages of LiDAR

Following are some of the benefits of LiDAR:

1. High Spatial Resolution: LiDAR provides highly detailed 3D maps, making it ideal for terrain mapping, urban planning, and environmental studies.
2. Wide Area Coverage: Efficiently scans large areas, making it suitable for autonomous vehicles, forestry management, and surveying.
3. Versatility: Works well in diverse environments, including forests, urban areas, and underwater mapping (bathymetric LiDAR).
4. Real-Time Data Processing: Rapidly collects and processes data, enabling real-time applications such as obstacle detection in autonomous vehicles.
5. High Precision: Offers centimeter-level accuracy in distance measurements, making it ideal for applications requiring precise mapping and modeling.

Advantages of LADAR

Following are some of the benefits of LADAR:

1. Superior Targeting Capabilities: Designed for precise targeting and tracking, often used in missile guidance and military operations.
2. Dynamic Object Tracking: Excels at following fast-moving objects, making it suitable for aerospace and defense applications.
3. Compact Design: Many LADAR systems are compact, allowing integration into drones, spacecraft, and other small platforms.
4. Enhanced Focus: Optimized for shorter-range, high-accuracy tasks like identifying and tracking specific objects in complex scenarios.
5. Robust in Critical Applications: Primarily developed for military and defense, LADAR offers reliable performance in mission-critical environments.

Disadvantages

Following are some of the limitations of LIDAR (i.e., LADAR):

1. It has limited capability to penetrate inside smoke, rain, fog, dust, clouds, etc.
2. It does not provide satisfactory performance for surveillance applications.
3. Tracking using LADAR is difficult.

Key Differences Between LiDAR and LADAR

Conclusion

Both LiDAR and LADAR are powerful technologies, each with its own set of strengths and applications. LiDAR excels in mapping and surveying tasks, thanks to its precision and wide-ranging capabilities. On the other hand, LADAR is preferred in military and aerospace sectors for its superior targeting and tracking functionalities. By understanding their differences and use cases, you can make an informed choice that aligns with your specific requirements.