A Laser Interferometric Miniature Sensor

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This is the second year of a Phase II Small Business Innovation Research (SBIR) contract geared towards the development of a new seismic sensor. Ground-based seismic monitoring systems have proven to be very capable in identifying nuclear tests, and can provide somewhat precise information on the location and yield of the explosive device. Making these measurements, however, currently requires very expensive and bulky seismometers that are difficult to deploy in places where they are most needed. A high performance, compact device can enable rapid deployment of large scale arrays, which can in turn be used to provide higher quality data ... continued below

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1.9 megabytes; 8 pages

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Carr, Dustin W.; Baldwin, Patrick C.; Milburn, Howard & Robinson, David September 12, 2011.

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Description

This is the second year of a Phase II Small Business Innovation Research (SBIR) contract geared towards the development of a new seismic sensor. Ground-based seismic monitoring systems have proven to be very capable in identifying nuclear tests, and can provide somewhat precise information on the location and yield of the explosive device. Making these measurements, however, currently requires very expensive and bulky seismometers that are difficult to deploy in places where they are most needed. A high performance, compact device can enable rapid deployment of large scale arrays, which can in turn be used to provide higher quality data during times of critical need. The use of a laser interferometer-based device has shown considerable promise, while also presenting significant challenges. The greatest strength of this optical readout technique is the ability to decouple the mechanical design from the transducer, thus enabling a miniaturized design that is not accessible with conventional sensing techniques. However, the nonlinearity in the optical response must be accounted for in the sensor output. Previously, we had proposed using a force-feedback approach to position the sensor at a point of maximum linearity. However, it can be shown that the combined nonlinearities of the optical response and the force-feedback curve necessarily results in a significant amount of unwanted noise at low frequencies. Having realized this, we have developed a new approach that eliminates force feedback, allowing the proof mass to move freely at all times. This takes advantage of some advanced optical spatial filtering that was developed at Symphony Acoustics for other types of sensors, and was recently adapted to this work. After processing the signals in real time, the digital output of the device is intrinsically linear, and the sensor can operate at any orientation with the same level of resolution, while instantly adapting to significant changes in orientation. Ultimately, we expect the dynamic range to be up to 180 dB. Currently, we have observed the noise floor in a 0.1 Hz to 10 Hz bandwidth to be near -160 dB/Hz relative to 1 m2/s4. To meet the objectives of this program, we are finalizing the design of a 3 axis sensor for shallow borehole deployments, with a diameter of 40 mm and a length a 150 mm.

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1.9 megabytes; 8 pages

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  • Report No.: DOE/ER/85108-1
  • Grant Number: FG02-08ER85108
  • DOI: 10.2172/1029209 | External Link
  • Office of Scientific & Technical Information Report Number: 1029209
  • Archival Resource Key: ark:/67531/metadc836234

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • September 12, 2011

Added to The UNT Digital Library

  • May 19, 2016, 3:16 p.m.

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  • Aug. 3, 2016, 6:36 p.m.

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Carr, Dustin W.; Baldwin, Patrick C.; Milburn, Howard & Robinson, David. A Laser Interferometric Miniature Sensor, report, September 12, 2011; United States. (digital.library.unt.edu/ark:/67531/metadc836234/: accessed January 17, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.