A team of researchers at the National Institute of Standards and Technology (NIST), Gaithersburg, MD, has demonstrated a laser-based imaging system that creates high-definition 3D maps of surfaces from as far away as 10.5 meters. They say that this method may be useful in diverse fields, including precision machining and assembly, as well as in forensics.
The NIST 3D mapping system combines a form of laser detection and ranging (LADAR), sensitive enough to detect weak reflected light, with the ranging accuracy made possible by frequency combs, which were previously demonstrated at NIST. The frequency comb , a tool for precisely measuring different frequencies of light, is used to continuously calibrate the laser in the imaging system.
Operating with laser power of just 9 milliwatts, NIST's 3D mapping system scans a target object point by point across a grid, measuring the distance to each point. The system uses the distance data to make a 3D image of about 1 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 micrometers in half a millisecond, with an accuracy that is traceable to a frequency standard.
The system has wide dynamic range, enabling precise 3D mapping of targets with varied surface types and reflective properties. The new method offers a unique set of capabilities compared to conventional 3D mapping techniques. It does not require a reference artifact to be placed next to the target, something typically required for interferometry-based systems.
Several manufacturers have expressed interest in the NIST system, which is currently about the size of a desktop but suitable for future potential conversion to a portable, chip-scale instrument.
