A new dual-comb LiDAR technique creates micron-scale 3D images of tiny metal objects, enabling precise non-contact inspection of hard-to-reach components.
Researchers at Heriot-Watt University have created a novel two-photon dual-comb LiDAR that can generate highly accurate 3D representations of tiny metal objects with micrometer accuracy.
The new method generated point cloud data sets of test aluminum targets and had measurement accuracies of 9 to 38 microns at a 40 cm distance. According to the researchers, the technology could be useful for verifying the correctness of fabrication of components in engines and other hard-to-access items without any physical contact.
As opposed to regular LiDAR systems that use nanosecond-scale light pulses and are employed for measuring large objects with an accuracy of a few centimeters, the new technique uses pulses lasting only a few hundreds femtoseconds. This approach combines ultra-precise laser timing with a nonlinear detection method.
Researchers also developed the first fully electronic method for achieving detection in dual-comb imaging. The approach uses two-photon absorption to convert returning light pulses directly into electrical signals.
To demonstrate the new method, the researchers collaborated with the Centre for Precision Technologies at the University of Huddersfield, which provided CNC-machined aluminium samples with various shapes such as circles, diamonds, squares, ledges, and counterbore holes. One object measured 50 × 50 × 30 mm.
Having demonstrated the proof of concept, the researchers are now working to improve the technique by scanning the laser beam across the object instead of physically moving the test object beneath the laser beam. They are also experimenting with higher pulse repetition rates to improve performance.
