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Instrumentation for passive sensing of diffusely modulated signatures



The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 5.4.c.(8) of the solicitation and within the AF Component-specific instructions. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. Please direct questions to the AF SBIR/STTR Contracting Officer, Ms. Gail Nyikon,

OBJECTIVE: Develop hardware to advance imaging techniques for remotely sensing low level earth surface vibrations via detection of diffusely modulated light; enhance survivability from lab to field, improve ranges to hundreds of kilometers.

DESCRIPTION: Recent work in the laboratory [1-3, 5-7] has demonstrated that detection of dim signals that indicate the presence of surface vibrations via diffuse light modulation can be conducted under controlled conditions, with results sufficient to provide initial proof of concept for the viability of diffuse light modulation-based methods.

The underlying scientific utility of diffuse light modulation has been understood for years [9], and development of specific applications is ongoing. However some technological gaps remain. Long-range detection on the ground is a key step on the path to detection from low Earth orbit or geosynchronous (GEO) orbit [8], and one of the limitations is the lack of an appropriately sensitive advanced sensor capable of high dynamic range that can tolerate field conditions, sense light very precisely (ideally at or near the photon shot noise limit), and remain portable and flexible for ongoing field work. Achieving this goal places significant demands on the imaging sensor, requiring a focal plane with a deep well capacity and low noise. Sensors that can function at spectral bandwidths that provide improved or even optimal chances of vibration detection would also be desirable. Spectral bandwidths for better detection probability may include subsets of the visible spectrum, or the non-visible spectra, depending on the phenomenology.

Accordingly, the goal of this topic is to produce sensor hardware that can make passive detection of surface vibrations via diffuse light modulation methodology at ranges in the regime of tens to hundreds of kilometers, perform in the field reliably, and/or provide a good probability of detection at these ranges. Active sensing devices such as vibrometers are not desirable. This hardware should be able to be field-deployed on the ground or in airplanes to demonstrate viability, that is, used in assorted environmental conditions, without requiring onerous amounts of supporting equipment (e.g., cryocooling hardware, extensive maintenance kits, heavy shock absorption systems, heavy power-generation systems) to be co-deployed.

In addition to the field deployment requirements, support for a path ahead is desirable. Evidence of a clear and graduated path to space from the field is a strong plus, as is availability of field support capability, to enable government users to conduct additional field data collection for later efforts. The capability to deliver multiple units may also be a factor worth considering, as will the ability to work on classified data if the effort begins to generate products at higher levels of classification.

PHASE I: Construct a prototype field deployable hardware system. Demonstrate the prototype under field-similar conditions, and identify major technical obstacles to field deployment, including such factors as sensitivity, data handling/storage, compatibility with other systems, and expected field lifetime.

PHASE II: Extend the field-deployable hardware system to airborne platforms and verify its performance under a set of varied environmental conditions, collecting data from a set of varied targets and in varied locations. Demonstrate ability to extract known vibration signals from collected data amidst clutter.

PHASE III DUAL USE APPLICATIONS: Package the field-deployable system for use by other government and commercial customers, e.g. passive detection of vibrations due to faults in bridges within the Department of Transportation. Demonstrate collection of data from very dim and unknown vibration sources, with an emphasis on demonstration from space, thereby implicitly extending the airborne theme referred to in Phase II.


  • Robert Shroll, Benjamin St. Peter, Steven Richtsmeier, Bridget Tannian, Elijah Jensen, John Kielkopf, and Wellesley Pereira, Remote optical detection of ground vibrations, Proc SPIE 9608, September 2015.
  • John Kielkopf, Elijah Jensen, Frank Clark, Bradley Noyes, Fractional intensity modulation of diffusely scattered light, Proc SPIE 9608, September 2015.
  • Jason Cline, Ryan Penny, Bridget Tannian, Neil Goldstein, John Kielkopf, Remote optical interrogation of vibrations in materials inspection applications, Proc SPIE 9608, September 2015.
  • Dan Slater, Rex Ridenoure, Passive Remote Acoustic Sensing in Aerospace Environments, Proc AIAA SPACE, 2015-4661, August 2015.
  • Frank Clark, Ryan Penney, Wellesley Pereira, John Kielkopf, Jason Cline, A passive optical technique to measure physical properties of a vibrating surface, Proc SPIE 9219, September 2014.
  • Alan Marchant, Chad Fish, Jie Yao, Phillip Cunio, Wellesley Pereira, Feasibility considerations for a long-range passive vibrometer, Proc SPIE 9219, September 2014.
  • Matthew Buoni, Wellesley Pereira, Reed A. Weber, Carlos Garcia-Cervera, Detecting small surface vibrations by passive electro-optical illumination, Proc SPIE 9219, September 2014.
  • R. Michel, J.-P. Ampuero, J.-P. Avouac, N. Lapusta, S. Leprince, D. C. Redding, and S. N. Somala, A Geostationary Optical Seismometer, Proof of Concept, IEEE Transactions on Geoscience and Remote Sensing, Vol 51, No 1, January 2013.
  • Wellesley Pereira, Frank Clark, Laila Jeong, Bradley Noyes, Paul Noah, Curtis Pacleb, Scott Dalrymple, Aaron Westphal, A., Hypertemporal Imaging Diffuse Modulation (HTI-DM) Experiment, AFRL-RV-HA-TR-2011-1010, February 2011.

KEYWORDS: BRDF, field packaging, photon counting, dim signal detection, shot noise limit


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