Laser Triangulation

A laser projects a dot or line, a camera views the spot from the side, and triangulation gives distance and profile.

Laser triangulation is an active optical ranging method: a laser projects a dot or a line onto an object, and a camera set a known distance away from the laser, viewing from a different angle, captures where the spot lands; the laser, camera, and spot form a triangle, and the spot’s position in the image gives the distance. Swapping the dot for a line turns this into line-laser profile scanning, which captures an entire cross-sectional profile in one shot; moving the object on a conveyor belt, or sweeping the sensor with a robot arm, stitches these profiles into a 3D point cloud. It is highly accurate, down to tens of micrometers, but its range is usually limited to within a few meters, and it struggles with occlusion and highly reflective surfaces. Industrially it is used for dimensional measurement, defect detection, and weld-seam tracking, a common approach in machine vision and 3D vision-guided robotics; structured-light cameras are based on the same triangulation principle.

ExampleA welding robot mounts a line-laser profile scanner in front of its torch (such as the Micro-Epsilon scanCONTROL 8x00, with 4,224 points per profile at a 10 kHz profile rate), measuring the weld seam’s cross-section position in real time and guiding the arm to correct its path along the seam.

Also called

Line-Laser Profiler, Laser Profilometer, Laser Profile Scanner

Related

Structured Light · Triangulation · Machine Vision · 3D Vision-Guided Robotics · Point Cloud · Time of Flight

Sources

Wikipedia: 3D scanning（Triangulation 一节） (Chinese)
KEYENCE LJ-X8000 2D/3D Laser Profiler
Micro-Epsilon scanCONTROL Laser Profile Scanners

As of

2026-09