Washington: Scientists have developed a laser-based imaging system that creates high-definition 3D maps of surfaces from as far away as 10.5 metres.
Researchers at the National Institute of Standards and Technology (NIST) in the US developed the 3D mapping system that combines a form of laser detection and ranging (LADAR), which is sensitive enough to detect weak reflected light, with the ranging 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.
Operating with laser power of just 9 milliwatts - which is safe for the eyes at the instrument's infrared wavelength - 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.
The system has wide dynamic range, enabling precise 3D mapping of targets with varied surface types and reflective properties.
Researchers demonstrated the range by scanning footprints in soil, vegetation such as cactus (imaging individual spines), and complex mechanical devices such as a piston for a motorcycle.
As an example application, NIST's 3D mapping system could be used to make virtual casts of forensic evidence such as footprints in dirt.
Conventional plaster casts that record impression evidence normally require a lot of effort to make and are difficult to compare to each other or to shoes.
Furthermore, conventional analysis can destroy the evidence. By contrast, a remotely created 3D image of a footprint can nondestructively reveal more details than a photograph, such as exact measurements of shoe tread.
The tread may show individual wear marks from a bicycle pedal, for example, a type of detail that could link a specific shoe to a crime scene.