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 Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

nachricht What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto

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: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>