Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

NIST laser comb system maps 3-D surfaces remotely for manufacturing, forensics

08.10.2014

Researchers at the National Institute of Standards and Technology (NIST) have demonstrated a laser-based imaging system that creates high-definition 3D maps of surfaces from as far away as 10.5 meters.* The method may be useful in diverse fields, including precision machining and assembly, as well as in forensics.

NIST's 3D mapping system 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, as 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.


This video shows the sole of a shoe as it appears from different perspectives in rendering software. The shoe was placed upside down on an optical table (seen as flat surface with regularly spaced holes). The colors indicate distance, with blue/purple indicating shorter distances (or higher areas of the shoe sole) and red/brown longer distances. In the second part of the movie detailing the shoe sole pattern, the color scale spans a range of about 10 millimeters (mm). The prominent shoe sole patterns are about 1-2 mm deep.

Credit: Baumann/NIST

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. 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. NIST 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.

The new NIST method offers a unique set of capabilities compared to conventional 3D mapping techniques. The NIST system is similar to optical coherence tomography, for example, but can operate much farther away from the target and is inherently accurate because of the frequency comb. The NIST system does not need a reference artifact to be placed next to the target, something typically required for interferometry-based systems.

LADAR typically measures distance based on the round-trip flight time of laser light, which reflects off the target and is detected by a sensor. In the NIST LADAR system, the laser sweeps continuously across a band of frequencies. The initial laser output is combined with the reflected light and the resulting "beat" signals are converted to voltage and analyzed by digital signal processing to generate time delay data, which is used to calculate the distance. (The difference in frequency between the transmitted and received signals increases with distance.)

This basic technique is well established .*** However, by including a frequency comb to continuously calibrate the swept laser, the NIST system can operate much more rapidly, yielding one measurement point every half a millisecond and simultaneously maintain sub-micrometer accuracy traceable to a frequency standard. Finally, the system uses real-time, fast processing digital electronics to produce fully calibrated, 3D megapixel images.

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.

Several manufacturers already 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. The research was funded by NIST and the Defense Advanced Research Projects Agency.

###

* E. Baumann, F.R. Giorgetta, J.D. Deschenes, W.C. Swann, I. Coddington and N.R. Newbury. Comb-calibrated laser ranging for three-dimensional surface profiling with micrometer-level precision at a distance. Optics Express. Vol. 22 Issue 21, Oct. 20, 2014. DOI:10.1364/OE.22.024914

** See 2009 NIST Tech Beat article, "NIST's LIDAR May Offer Peerless Precision in Remote Measurements," at http://www.nist.gov/pml/div686/lidar_060209.cfm. NIST researchers also reported in 2013 that the LADAR system without the 3D imaging capability is accurate to within 1 micrometer (E. Baumann, F.R. Giorgetta, I. Coddington, L.C. Sinclair, K. Knabe, W.C. Swann and N.R. Newbury, Comb-calibrated frequency ­modulated continuous-wave LADAR for absolute distance measurements, Opt. Lett., vol. 38,no. 12, pp. 2026-2028).

*** This technique is called frequency modulated continuous wave (FMCW) laser detection and ranging (LADAR).

Laura Ost | Eurek Alert!

More articles from Physics and Astronomy:

nachricht Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology

nachricht Physicists discover mechanism behind granular capillary effect
24.05.2017 | University of Cologne

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Physicists discover mechanism behind granular capillary effect

24.05.2017 | Physics and Astronomy

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017 | Physics and Astronomy

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>