A lidar beam is the pulse of light emitted by a Lidar system to gather information about a target or environment.
Lidar stands for Light Detection and Ranging. As defined, Lidar is a remote sensing method used to examine the surface of the Earth. This technology works by sending out light pulses – the lidar beams – and measuring the time it takes for these pulses to return after reflecting off objects on the surface.
Think of the lidar beam as the primary tool used in this remote sensing process. Without the emitted light beam, there would be no signal to detect and measure.
How the Lidar Beam Works
- Emission: The Lidar system emits a focused beam of light, often from a laser source. These beams are typically sent out very rapidly, in pulses.
- Interaction: The beam travels through the air and interacts with objects on the ground, vegetation, buildings, or even the ground itself.
- Reflection: A portion of the light reflects off these surfaces and travels back towards the Lidar sensor.
- Detection: The Lidar sensor detects the returning light pulse.
- Measurement: By precisely measuring the time it took for the pulse to travel out and back, the system calculates the distance to the object it hit.
These distance measurements, combined with the known position and orientation of the Lidar sensor (often mounted on an aircraft or vehicle), create detailed 3D information about the scanned area. For example, lidar data collected using NOAA survey aircraft reveals a top-down and side view of Loggerhead Key Lighthouse, Dry Tortugas, Florida, based on the return signals from these light beams.
Key Characteristics of a Lidar Beam
Lidar beams are typically designed with specific properties to be effective for sensing:
- Wavelength: Often uses infrared, visible, or ultraviolet light. The choice depends on the application (e.g., atmospheric studies vs. topographic mapping).
- Pulsed: Emitted as short, rapid pulses to allow for precise timing and distance measurement.
- Directional: The beam is focused to travel in a specific direction. Lidar systems often scan the beam or use multiple beams to cover an area.
- Eye Safety: Depending on the power and wavelength, beams are designed with eye safety considerations, especially for terrestrial or urban scanning.
| Characteristic | Description | Importance |
|---|---|---|
| Light Source | Typically a laser | Precise, powerful light pulses |
| Nature | Emitted as pulses | Enables time-of-flight measurement |
| Role | Interacts with objects, reflects back to sensor | Gathers distance data |
The lidar beam, therefore, is the carrier of the Lidar system's interrogation of the environment, essential for gathering the data that forms detailed 3D maps and models. Learn more about remote sensing methods here.
