Understanding the Hardware: LiDAR & Phase-Based Scanning

LiDAR

The "time-of-flight" method

Laser Imaging, Detection, and Ranging (also called Light Detection and Ranging) or LiDAR, is based on a principle known as time-of-flight. This uses a pulsed laser to emit a beam, along with a mirror that deflects that beam toward the scan area, and finally, an optical receiver to detect the laser pulse and reflect it from the object to the scanner.

The time-of-flight method operates based on this formula: (Distance = (Speed of Light x Time of Flight) / 2). It uses the known speed of light and the time it takes for the laser pulse to be emitted, bounce off the object, and ultimately return to the 3D laser scanner to calculate the distance from the object to the scanner.

Although LiDAR 3D laser scanning does not collect data as quickly as phase-based scanning, it can be used from greater distances.

Phase-Based Scanning

The laser scanner emits a constant beam of energy

Phase-based 3D laser scanning emits a constant laser beam into multiple phases. It then compares the phase shifts of the returned laser energy. The laser scanner uses phase-shift algorithms to determine the distance, based on the unique properties of each individual phase based on this formula: (Time of Flight = Phase Shift / (2π x Modulation Frequency).

Phase-based scanners can collect data at a much faster speed than time-of-flight scanners, but their effective distance is much shorter. Additionally, phase-based scanners typically have more "noise," or false data, than time-of-flight scanners.

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