New LiDAR approach achieves micron-scale precision for tiny parts

A new LiDAR imaging approach, detailed in the journal Optics Letters, promises significantly greater precision and accuracy for measuring small objects compared to conventional systems. Developed by researchers at Heriot-Watt University, the method is based on two-photon dual-comb ranging and can create detailed 3D representations of small aluminum objects with micron-scale precision from a distance of 40 centimeters.

This technique differs from LiDAR systems typically used in autonomous vehicles, which are designed to measure large objects at greater distances with centimeter-level accuracy. The new optical dual-comb LiDAR imaging technique offers a noncontact measurement solution, which could be invaluable in manufacturing for verifying critical features on components, especially those that are difficult to access.

The research, a collaboration with Renishaw PLC, builds upon previous work that achieved highly accurate single-point measurements. The advancement extends this capability to full imaging of small metal objects by combining ultra-precise laser timing with a nonlinear detection method. Instead of nanosecond-scale light pulses used in conventional LiDAR, this system utilizes pulses lasting only a few hundred femtoseconds, enabling enhanced measurement accuracy.

The researchers demonstrated their method using CNC-milled aluminum objects provided by the University of Huddersfield's Centre for Precision Technologies. These objects featured various intricate designs, including circles, diamonds, ledges, and counterbored holes. The two-photon dual-comb LiDAR successfully rendered 3D point-cloud data sets with micron precision, achieving distance accuracies between 9 and 38 microns on the test surfaces.