Laser-ranging system accurately maps 3D surface images

American researchers have demonstrated a laser-based imaging system that creates high-definition 3D maps of surfaces from as far away as 10.5 metres.

The method may be useful in diverse fields, including precision machining and assembly as well as in forensics.

The 3D mapping system combines a form of laser detection and ranging (LADAR) which is sensitive enough to detect weak reflected light with the accuracy made possible by frequency combs.

The frequency comb, a tool for precisely measuring different frequencies of light, is used to continuously calibrate the laser in the imaging system.

The 3D mapping system scans a target object point by point across a grid.

The system uses the distance data to make a 3D image of about one million pixels in less than 8.5 minutes at the current scanning rate.

"Distances to points on a rough surface that reflects light in many directions can be determined to within 10 micro-meters in half a milli-second, with an accuracy that is traceable to a frequency standard," said researchers from Maryland-based National Institute of Standards and Technology (NIST).

The system has wide dynamic range, enabling precise 3D mapping of targets with varied surface types and reflective properties.

NIST researchers demonstrated the range by scanning footprints in soil, vegetation such as cactus (imaging individual spines) and complex mechanical devices such as the piston of a motorcycle.

The research is funded by NIST and the Defense Advanced Research Projects Agency.