Multimodal Remote Vibrometer for Infrastructure Interrogation

Project # 23-010 | Year 1 of 2

^aSteven Koppenjan, ^aDavid Baldwin, ^aJoe Mendez, ^aPaul Taylor, ^aEric Larson, ^bEbrahim Saberinia

Special Technologies Lab (STL)^a, University: Nevada Las Vegas^b
_{This work was done by Mission Support and Test Services, LLC, under Contract No. DE-NA0003624 with the U.S. Department of Energy, the NNSA Office of Defense Programs, and supported by the Site-Directed Research and Development Program. DOE/NV/03624–1907.}

Abstract

The goal of this SDRD is to develop a next generation detection system to improve methods of remotely characterizing facilities of interest and increase standoff from hundreds of meters to multi-kilometer ranges. The Multi-Modal Remote Vibrometer for Infrastructure Interrogation combines active dual comb laser techniques, turbulence mitigation and micro-doppler radar. The effort will be a low to mid-test readiness level (TRL) effort to move lab bench scale Dual Comb Spectroscopy (DCS) techniques for remote vibrometry to field in a rapid, sensitive, and wide frequency capability for remotely characterizing vibrational signatures including correction for phase errors associated with atmospheric turbulence. DCS sampling rates exceeding 100 kHz will create high signal-to-noise ratio (SNR) waveforms across the acoustic frequency range. Combining with micro-Doppler radar, we create a continuous frequency range from infrasound to acoustic frequencies and create opportunities for combined temporal data analysis for more effective characterization of these weak signals.

Tie to Mission

This work is directly related to the National Nuclear Security Administration (NNSA) mission and treaty verification. A previous Defense Nuclear Nonproliferation (DNN) lifecycle, led by the Nevada National Security Site (NNSS) Special Technologies Laboratory (STL), showed the strength of remote vibrometry in addressing this problem. In that project, STL, Lawrence Livermore National Laboratory (LLNL), and Los Alamos National Laboratory (LANL) developed models and successfully developed algorithms to compensate for atmospheric turbulence improving the detection range of a speckle vibrometer.

Technical Accomplishments

We designed and built a prototype offset frequency all-in-fiber vibrometer using 100 MHz acousto-optic modulation (AOM) for optical offset frequency heterodyne. The laser interferometric vibrometry is designed as a pair of single tooth combs – still making the measurements in the same manner as a DCS, but not strictly with “combs.”

Open path “Air Gap” measurements optical vibrometer: The laser-based interferometer has proven successful at detecting vibration in the laboratory setting at 10-mm range. We assembled 3-GHz radar hardware for micro-Doppler measurements. Additionally, we collected lab data for calibration and initial analysis as well as data on several field targets.

Conclusions and Path Forward

Given that the physical motions being measured are highly correlated, multimodal processing of waveforms is anticipated to produce higher fidelity than any single sensor technology. We will adapt algorithms to data (with the University of Nevada Las Vegas (UNLV) partner) to evaluate several detection and classification techniques for analysis of both simulated and collected data. An ideal programmatic customer for this work includes NA-22 non-proliferation ventures.

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