Publications

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The following is a list of publications by Thomas W Elmer II, in reverse order by date. Unless otherwise credited, figures shown are by me.

Contents

Journal Articles

Remote sensing of patterns of cardiac activity on an ambulatory subject using millimeter-wave interferometry and statistical methods

ECG with superimposed heartbeats gathered with breathing using both the new method and the original, non-statistical method. Credits: I. Mikhelson
  • Type: Full Length Journal Article
  • Authors: Ilya V. Mikhelson, Sasan Bakhtiari, Thomas W. Elmer II, Alan V. Sahakian
  • Published in: Medical & Biological Engineering & Computing
    • Vol. 51, Issue 1-2, pp. 135-142
    • DOI: 10.1007/s11517-012-0977-6
    • (Originally prepared for IEEE Trans. on Biomedical Engineering as "Remote Sensing of Patterns of Cardiac Activity Using Statistical Methods and Non-Linear Optimization")
  • Abstract
    • Using a 94-GHz millimeter-wave interferometer, we are able to calculate the relative displacement of an object. When aimed at the chest of a human subject, we measure the minute motions of the chest due to cardiac activity. After processing the data using a wavelet multiresolution decomposition, we are able to obtain a signal with peaks at heartbeat temporal locations. In order for these heartbeat temporal locations to be accurate, the reflected signal must not be very noisy. Since there is noise in all but the most ideal conditions, we created a statistical algorithm in order to compensate for unconfident temporal locations as computed by the wavelet transform. By analyzing the statistics of the peak locations, we fill in missing heartbeat temporal locations and eliminate superfluous ones. Along with this, we adapt the processing procedure to the current signal, as opposed to using the same method for all signals. With this method, we are able to find the heart rate of ambulatory subjects without any physical contact.
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Noncontact Millimeter-Wave Real-Time Detection and Tracking of Heart Rate on an Ambulatory Subject

System maintaining identity when another human is close to the subject of interest. Credits: I. Mikhelson
  • Type: Full Length Journal Article
  • Authors: Ilya V. Mikhelson, Philip Lee, Sasan Bakhtiari, Thomas W. Elmer II, Aggelos K. Katsaggelos, and Alan V. Sahakian*
  • Published in: IEEE Transactions on Information Technology in Biomedicine
    • Vol. 16, Issue 5, pp. 927-934
    • DOI: 10.1109/TITB.2012.2204760
    • Originally submitted as "Non-Contact Millimeter-Wave Real-Time Detection and Tracking of Heart Rate with a Non-Stationary Subject". Rejected due to a one-revision policy, then new data was collected and the paper revised for re-submission.
  • Abstract
    • This paper presents a solution to an aiming problem in the remote sensing of vital signs using an integration of two systems. The problem is that to collect meaningful data with a millimeter-wave sensor, the antenna must be pointed very precisely at the subject's chest. Even small movements could make the data unreliable. To solve this problem, we attached a camera to the millimeter-wave antenna, and mounted this combined system on a pan/tilt base. Our algorithm initially finds a subject's face and then tracks him/her through subsequent frames, while calculating the position of the subject's chest. For each frame, the camera sends the location of the chest to the pan/tilt base, which rotates accordingly to make the antenna point at the subject's chest. This paper presents a system for concurrent tracking and data acquisition with results from some sample scenarios.
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    • © 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
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Ka Band: Standoff Through-the-Wall Sensing at Ka Band

This was an alternate title page I submitted for the article. This was the small title variant, with a large title variant to have title text replacing the two figure insets.
  • Type: Full Length Journal Article
  • Authors: S. Liao*, T. Elmer, S. Bakhtiari, N. Gopalsami, N. Cox, J. Wiencek, and A. C. Raptis
  • Published In: Journal of Materials Evaluation
    • 2012 Oct, Vol. 70, No. 10, pp. 1136-1144
    • DOI: (unknown)
    • Very good reviews; we were offered choice between "featured article" and "technical paper". We chose "feature".
  • Abstract
    • Conventional microwave remote sensing/imaging of through-the-wall objects made of different materials is usually performed at frequencies below 3 GHz that provide relatively low spatial resolution. In this paper, we evaluate the ability and sensitivity of high-frequency microwave or millimeter wave standoff sensing of through-the-wall objects to achieve high spatial resolution. The target under study is a sandwich structure consisting of different object materials placed between two wall blocks. An Agilent® PNA-X series (model N5245A) vector network analyzer is used to sweep over the entire Ka-band (26.5 GHz to 40 GHz). The beam is then directed to a standard rectangular horn antenna and collimated by a 6-inch-diameter Gaussian lens towards the sandwich structure (wall block/object/wall block). The reflected electromagnetic wave is picked up by the same system as the complex S-parameter S11. Both amplitude and phase of the reflected signal are used to recognize different materials sandwiched between the cement blocks. The experimental results are compared with the theoretical calculations, which show satisfactory agreement for the cases evaluated in this work.
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Passive millimeter wave imaging with compressive sensing

Illustration of how a folded observation mask corresponds to a row in the cyclic Hadamard S-matrix. (Illustration included in the paper in another form, however this was my preferred form.)
  • Type: Full Length Journal Article
  • Authors: Nachappa Gopalsami, Shaolin Liao, Thomas W. Elmer, Eugene R. Koehl, Alexander Heifetz, Apostolos C. Raptis, Leonidas Spinoulas, and Aggelos K. Katsaggelos
  • Published in: Optical Engineering
    • Invited paper, special Issue on Millimeter Waves and Terahertz Imaging
    • Vol. 51, Issue 9, pp. 091614-1 - 091614-9
    • DOI: 10.1117/1.OE.51.9.091614
  • Abstract
    • Passive millimeter-wave (PMMW) imagers using a single radiometer, called single pixel imagers, employ raster scanning to produce images. A serious drawback of such a single pixel imaging system is the long acquisition time needed to produce a high-fidelity image, arising from two factors: (a) the time to scan the whole scene pixel by pixel and (b) the integration time for each pixel to achieve adequate signal to noise ratio. Recently, compressive sensing (CS) has been developed for single-pixel optical cameras to significantly reduce the imaging time and at the same time produce high-fidelity images by exploiting the sparsity of the data in some transform domain. While the efficacy of CS has been established for single-pixel optical systems, its application to PMMW imaging is not straightforward due to its (a) longer wavelength by three to four orders of magnitude that suffers high diffraction losses at finite size spatial waveform modulators and (b) weaker radiation intensity, for example, by eight orders of magnitude less than that of infrared. We present the development and implementation of a CS technique for PMMW imagers and shows a factor-of-ten increase in imaging speed. ©2012 Society of Photo-Optical Instrumentation Engineers (SPIE).
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    • Gopalsami N, Liao S, Elmer TW, et al; Passive millimeter-wave imaging with compressive sensing. Opt. Eng. 0001;51(9):091614-1-091614-9. doi:10.1117/1.OE.51.9.091614

      ©2012 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
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Optimized compressive sampling for passive millimeter-wave imaging

Passive mm wave image of a pair of scissors
  • Type: Full Length Journal Article
  • Authors: Leonidas Spinoulas, Jin Qi, Aggelos K. Katsaggelos, Thomas W. Elmer, Nachappa Gopalsami, and Apostolos C. Raptis
  • Published in: Applied Optics
  • Abstract:
    • In this paper, we briefly describe a single detector passive millimeter-wave imaging system, which has been previously presented. The system uses a cyclic sensing matrix to acquire incoherent measurements of the observed scene and then reconstructs the image using a Bayesian approach. The cyclic nature of the sensing matrix allows for the design of a single unified and compact mask that provides all the required random masks in a convenient way, such that no mechanical mask exchange is needed. Based on this setup, we primarily propose the optimal adaptive selection of sampling submasks out of the full cyclic mask to obtain improved reconstruction results. The reconstructed images show the feasibility of the imaging system as well as its improved performance through the proposed sampling scheme.
  • Notes
    • This article was almost published without including our names, even though it included our data, my sampling technique / explanation for why it works, and our figures were 'borrowed' liberally. Changes were made at the last minute before publication to include authorship after we stumbled on the paper online in pre-pub form.
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Development of Ultrasonic Waveguide Techniques for Under-Sodium Viewing

Under-sodium imaging results of a calibration target
  • Type: Full Length Journal Article
  • Authors: Ke Wang, Hual-Te Chien, Thomas W. Elmer, William P. Pawrence, David M. Engel, and Shuh-Haw Sheen
  • Published in: NDT&E International
  • Abstract:
    • An ultrasonic imaging system based on the waveguide technique was developed to provide in-service inspection of reactor core of a sodium-cooled fast reactors (SFR) and potential applications in other hostile environments. By using the ultrasonic waveguide technique, we overcome the major technical challenge in developing an under-sodium viewing (USV) system that can withstand the high-temperature and corrosive environment. The chosen design of the prototype waveguide (WG) is a hybrid of bundle and spiraled-sheet WG. The prototypes show high detection sensitivity with minimal background noise by effectively reducing spurious echoes and mode conversions. Tests on prototype waveguide transducers were conducted in liquid sodium up to 6501 F. C-scan images of the targets were successfully developed from both time-of-flight and amplitude variations of the reflected echoes. The ultrasonic waveguide imaging system demonstrates a capability of detecting defects with 1 mm width and 0.5 mm depth under molten sodium.
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    • NOTICE: this is the author’s version of a work that was accepted for publication in NDT & E International. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in NDT & E International, VOL#49, July 2012.
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Passive Millimeter-Wave Dual-Polarization Imagers

Horizontal-polarization image (top) and polarization-difference image (bottom) of a car overlaid on the optical image
  • Type: Full Length Journal Article
  • Authors: Shaolin Liao, Nachappa Gopalsami, Thomas W. Elmer, II, Eugene R. Koehl, Alexander Heifetz, Keenan Avers, Eric Dieckman, and Apostolos C. Raptis
  • Published in: Instrumentation and Measurement, IEEE Transactions on
  • Status: Accepted
  • Abstract
    • We have developed two passive millimeter-wave(mmW)imagers for terrestrial remote sensing: one is an integrated imaging and spectroscopy system in the 146-154 GHz range with 16 channels of 500 MHz bandwidth each and the other is a single channel dual polarized imaging radiometer in the 70-100 GHz range. The imaging in both systems is implemented through translation of a 15cm Gaussian dielectric imaging lens. We compared the outdoor images of objects like car, vegetation, sky, and ground by both the systems under various weather conditions including clear, cloudy and rainy times. Ray-tracing simulation with radiative transfer equation was used to quantify the polarization diversity of the acquired images.
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    • © 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
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Nuclear Radiation-Induced Atmospheric Air Breakdown in a Spark Gap

Triangular sweep of dc power supply from 0 to 4 kV over a 30 s period (green line) and the corresponding mmW signal (blue line) without (unshaded) and with (shaded) γ-ray radiation.
  • Type: Full Length Journal Article
  • Authors: S. Liao, N. Gopalsami, E. R. Koehl, T. W. Elmer, A. Heifetz, H-T. Chien, and A. C. Raptis
  • Published in: IEEE Transactions on Plasma Science
  • Abstract
    • We have investigated the effect of pre-ionization by a radioactive 137Cs γ-ray source on the atmospheric air breakdown conditions in a high-voltage spark gap. A standoff millimeter-wave (mmW) system was used to monitor the breakdown properties. A decrease in breakdown threshold was observed with an increase of radiation dose. We attribute this to a space charge-controlled electron diffusion process in a cloud of radiation-induced ion species of both polarities. The space charge-dependent diffusion coefficient was determined from the measurement data. In addition, we found that the breakdown process shows random spikes with Poisson–like statistical feature. These findings portend the feasibility of remote detection of nuclear radiation using high-power mmWs.
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    • © 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
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Compact Millimeter Wave Sensor for Remote Monitoring of Vital Signs

Measurement showing heart-rate of a subject returning to rest after brief exercise
  • Type: Full Length Journal Article
  • Authors: Sasan Bakhtiari*, Thomas W. Elmer, Nicholas M. Cox, Nachappa Gopalsami, Appostolos C. Raptis, Shaolin Liao, Ilya Mikhelson, and Alan V. Sahakian
  • Published In: IEEE Transactions on Instrumentation and Measurement
  • Abstract:
    • A compact millimeter wave (MMW) sensor has been developed for remote monitoring of human vital signs (heart and respiration rate). The low-power homodyne transceiver operating at 94 GHz was assembled by using solid-state active and passive block-type components and can be battery operated. A description of the MMW system front-end and the back-end acquisition hardware and software is presented. Representative test case results on the application of various signal processing and data analysis algorithms developed to extract faint physiological signals of interest in presence of strong background interference are provided. Although the laboratory experiments so far have been limited to standoff distances of up to fifteen meters, the upper limit of the detection range is expected to be higher. In comparison to its microwave counterparts, the MMW system described here provides higher directivity, increased sensitivity, and longer detection range for measuring subtle mechanical displacements associated with heart and respiration functions. The system may be adapted for use in a wide range of standoff sensing applications including for patient health care, structural health monitoring, nondestructive testing, biometric sensing, and remote vibrometry in general.
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    • © 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
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Microwave Remote Sensing of Ionized Air

Measured RCS per square meter in the Ka-band (26.5–40 GHz) for three cycles when the NIG is on and off. Credits: S. Liao
  • Type: Full Length Journal Article
  • Authors: S. Liao*, N. Gopalsami, A. Heifetz, T. Elmer, P. Fiflis, E. R. Koehl, H. T. Chien, and A. C. Raptis
  • Published In: IEEE Geoscience and Remote Sensing Letters
  • Abstract:
    • We present observations of microwave scattering from ambient room air ionized with a negative ion generator. The frequency dependence of the radar cross section of ionized air was measured from 26.5 to 40 GHz (Ka-band) in a bistatic mode with an Agilent PNA-X series (model N5245A) vector network analyzer. A detailed calibration scheme is provided to minimize the effect of the stray background field and system frequency response on the target reflection. The feasibility of detecting the microwave reflection from ionized air portends many potential applications such as remote sensing of atmospheric ionization and remote detection of radioactive ionization of air.
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    • © 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
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A Real-time Heart Rate Analysis for a Remote Millimeter Wave I-Q Sensor

Detection of heartbeats. Credits: S. Liao
  • Type: Full Length Journal Article
  • Authors: Bakhtiari, S.; Liao, S.; Elmer II, T.; “Sami” Gopalsami , N.; Raptis, A. C.;
  • Published In: IEEE Transactions on Biomedical Engineering
  • Abstract:
    • This article analyzes Heart Rate (HR) information from physiological tracings collected with a remote millimeter wave (mmW) I-Q sensor for biometric monitoring applications. A parameter optimization method based on the nonlinear Levenberg-Marquardt (LM) algorithm is used. The mmW sensor works at 94 GHz and can detect the vital signs of a human subject from a few to tens of meters away. The reflected mmW signal is typically affected by respiration, body movement, background noise and electronic system noise. Processing of the mmW radar signal is thus necessary to obtain the true HR. The down-converted received signal in this case consists of both the real part (I-branch) and the imaginary part (Q-branch), which can be considered as the cosine and sine of the received phase of HR signal. Instead of fitting the converted phase angle signal, the method directly fits the real and imaginary parts of the HR signal, which circumvents the need for phase unwrapping. This is particularly useful when the signal-to-noise ratio (SNR) is low. Also the method identifies both beat-to-beat HR and individual heartbeat magnitude, which is valuable for some medical diagnosis applications. The mean HR here is compared to that obtained using the Discrete Fourier Transform (DFT).
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    • © 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
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Remote Sensing of Heart Rate and Patterns of Respiration Using 94 GHz Millimeter Wave Interferometry

  • Type: Full Length Journal Article
  • Authors: Mikhelson, I. V.;Bakhtiari, S.;Elmer, II, T. W.;Sahakian, A. V.
  • Published In: IEEE Transactions on Biomedical Engineering
  • Abstract
    • Using continuous wave, 94 GHz millimeter-wave interferometry, a signal representing chest wall motion can be obtained that contains both the heart rate and respiration patterns of a human subject. These components have to be separated from each other in the received signal. Our method was to use the quadrature and in-phase components of the signal, after removing the mean of each, to find the phase, unwrap it, and convert it to a displacement measurement. Using this, the power spectrum was examined for peaks, which corresponded to the heart rate and respiration rate. The displacement waveform of the chest was also analyzed for discrete heartbeats using a novel wavelet decomposition technique.
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    • © 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
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  • Citations

Visual Measurement of Suture Strain for Robotic Surgery

Steps in the marker detection process
  • Type: Full Length Journal Article
  • Authors: John Martell, Thomas Elmer, Nachappa Gopalsami, and Young Soo Park
  • Published in: Computational and Mathematical Methods in Medicine (formerly Journal of Theoretical Medicine)
  • Abstract:
    • Minimally invasive surgical procedures offer advantages of smaller incisions, decreased hospital length of stay, and rapid postoperative recovery to the patient. Surgical robots improve access and visualization intraoperatively and have expanded the indications for minimally invasive procedures. A limitation of the DaVinci surgical robot is a lack of sensory feedback to the operative surgeon. Experienced robotic surgeons use visual interpretation of tissue and suture deformation as a surrogate for tactile feedback. A difficulty encountered during robotic surgery is maintaining adequate suture tension while tying knots or following a running anastomotic suture. Displaying suture strain in real time has potential to decrease the learning curve and improve the performance and safety of robotic surgical procedures. Conventional strain measurement methods involve installation of complex sensors on the robotic instruments. This paper presents a noninvasive video processing-based method to determine strain in surgical sutures. The method accurately calculates strain in suture by processing video from the existing surgical camera, making implementation uncomplicated. The video analysis method was developed and validated using video of suture strain standards on a servohydraulic testing system. The video-based suture strain algorithm is shown capable of measuring suture strains of 0.2% with subpixel resolution and proven reliability under various conditions.
  • Download:
    • John Martell, Thomas Elmer, Nachappa Gopalsami, and Young Soo Park, “Visual Measurement of Suture Strain for Robotic Surgery,” Computational and Mathematical Methods in Medicine, vol. 2011, Article ID 879086, 9 pages, 2011. doi:10.1155/2011/879086

      Copyright © 2011 John Martell et al. This is an open access article distributed under the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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  • Citations
    • "Robotic-Assisted Laparoscopic Transection and Repair of an Obturator Nerve During Pelvic Lymphadenectomy for Endometrial Cancer", DOI: 10.1097/AOG.0b013e31823d0c4f

Application of millimeter-wave radiometry for remote chemical detection.

Conference papers

Remote sensing of heart rate using millimeter-wave interferometry and probabilistic interpolation

  • Type: Full Length Conference Paper
  • Authors: Ilya V. Mikhelson, Sasan Bakhtiari, Thomas W. Elmer, Shaolin Liao, Alan V. Sahakian
  • Conference: SPIE Defense, Security, and Sensing 2013
    • Date: 2013.05.02
  • Status: Presented
  • Abstract
    • Using a 94-GHz homodyne interferometer employing a highly-directional quasi-optical lens antenna aimed at a human subject's chest, we can measure chest wall displacement from up to 10m away and through common clothing. Within the chest displacement signal are motions due to cardiac activity, respiration, and gross body movement. Our goal is to find the heart rate of the subject being monitored, which implies isolation of the minute movements due to cardiac activity from the much larger movements due to respiration and body movement. To accomplish this, we first find a subset of the true heartbeat temporal locations (called confident" heartbeats) in the displacement signal using a multi-resolution wavelet approach, utilizing Symlet wavelets. Although the chest displacement due to cardiac activity is orders of magnitude smaller than that due to respiration and body movement, wavelets find those heartbeat locations due to several useful properties, such as shape matching, high-pass filtering, and vanishing moments. Using the assumption that the confident" heartbeats are randomly selected from the set of all heartbeats, we are able to find the maximum a posteriori statistics of an inverse Gaussian probability distribution modeling the inter-heartbeat times. We then analyze the confident" heartbeats and decide which heartbeats are probabilistically correct and which are not, based on the inverse Gaussian distribution we calculated earlier. The union of the confident" set, after pruning, and the interpolated set forms a very close approximation to the true heartbeat temporal location set, and thus allows us to accurately calculate a heart rate.
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    • Ilya V. Mikhelson ; Sasan Bakhtiari ; Thomas W. Elmer ; Shaolin Liao ; Alan V. Sahakian; Remote sensing of heart rate using millimeter-wave interferometry and probabilistic interpolation. Proc. SPIE 8719, Smart Biomedical and Physiological Sensor Technology X, 87190M (May 31, 2013); DOI: 10.1117/12.2015282. (Purchase published version)

      Copyright 2013 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
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Visual Measurement Of Suture Tension For Minimally Invasive Surgery

  • Type: Conference Abstract
  • Authors: Young Soo Park, John Martell, Pawel Dworzanski, Thomas Elmer, Nachappa Gopalsami
  • Conference: Engineering and Urology Society 27th Annual Meeting
    • Sponsor: Engineering and Urology Society
    • Date: 2012-05-19
  • Status: presented
  • Abstract
    • Introduction: We have demonstrated feasibility of real-time video image processing to measure suture strain during surgery. This will be instrumental for visual-haptic feedback in robotic and laparoscopic surgery.
      Methods: A video image processing algorithm is developed which incorporates functionalities of suture line detection, intensity profiling, frequency analysis, and strain computation. The algorithm was implemented in C++ with image/data processing libraries. Particular data processing techniques are added to improve the accuracy and robustness of the measurement. The optimized code was validated to run at 25 frames per second. A series of cyclic strain tests was performed on barbed surgical suture using Instron strain test system. The algorithm was applied on the test video and the strain computation was evaluated against the test reference profile.
      Results: The program was able to detect up to 0.2% strain, which is an order of magnitude (60 times) smaller than the lowest breaking strain of commercially available surgical sutures. In addition, the frequency based approach is expected to be more robust in real situations, such as occlusion, and applicable to wide variety of surgical sutures.
      Conclusion: The developed non-contact approach will require minimal installation with existing endoscopy, and yet to provide sensory feedback with highly accurate measurement of suture strain.

Millimeter Wave Doppler Sensor for Nondestructive Evaluation of Materials

  • Type: Full Length Conference Paper
  • Authors: S. Liao, S. Bakhtiari, T. Elmer, B. Lawrence, E. R. Koehl, N. Gopalsami, and A. Raptis
  • Conference: ASNT 21st Annual Research Symposium and Spring Conference
    • Sponsor: American Society for Nondestructive Testing
    • Date: 2012.03.21
  • Status: presented
  • Abstract
    • Resonance signatures are intrinsic characteristics of objects under evaluation. Probing the resonance signatures can reveal useful object information the materials made, geometries, presence of defects, and other characteristics of the object under test. When combined with millimeter wave Doppler sensor and remote excitation source, this new type of Non-Destructive Evaluation (NDE) method can work in a non-contact manner, which is an important complement of the conventional NDE method such as acoustic/ultra-sound method and can be used for both civil and national security applications, e.g., cracks/defaults diagnostics, shielded/sealed cargo container identification, and chemical/biological warhead inspection etc. In this paper, we evaluate the performance of such NDE tool. Our recently built 94 GHz I-Q Doppler sensor monitors the mechanical vibration signature of the object under interrogation that is induced by continuous wave excitation. For proof-of-principle demonstrations, the test objects were mechanically excited by an electronically controlled shaker using sinusoidal wave of at various frequencies ranging from DC to 200 Hz. We will present a number of laboratory test results and will discuss the method’s applicability to some practical NDE applications.
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Millimeter Wave I-Q Standoff Biosensor

  • Type: Full Length Conference Paper
  • Authors: Shaolin Liao, Sasan Bakhtiari, Thomas Elmer, Apostolos C. Raptis, Ilya V. Mikhelson, Alan V. Sahakian
  • Conference: SPIE Defense, Security, and Sensing 2012
    • Date: 2012.04.25
  • Status: Presented
  • Abstract
    • A continuous wave (CW) 94-GHz millimeter wave (mmW) standoff biosensor has been developed for remote biometric sensing applications. The sensor measures the demodulated in-phase (I) and quadrature-phase (Q) components of the received reflected mmW signal from a subject. Both amplitude and phase of the reflected signal are obtained from downconverted I and Q channels from the quadrature mixer. The mmW sensor can faithfully monitor human vital signs (heartbeat and respiration) at relatively long standoff distances. Principle Component Analysis (PCA) is used to extract the heartbeat, the respiration and the body motion signals. The approach allows one to deduce information about amplitude and beat-to-beat rate of the respiration and the heartbeat. Experimental results collected from a subject were analyzed and compared to the signal obtained with a three-electrode ECG monitoring instrument.
  • Download:
    • Shaolin Liao ; Sasan Bakhtiari ; Thomas Elmer ; Apostolos C. Raptis ; Ilya V. Mikhelson ; Alan V. Sahakian; Millimeter wave I-Q standoff biosensor. Proc. SPIE 8371, Sensing Technologies for Global Health, Military Medicine, Disaster Response, and Environmental Monitoring II; and Biometric Technology for Human Identification IX, 83711D (May 1, 2012); DOI: 10.1117/12.924241. (Purchase published version)

      Copyright 2012 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
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Evaluation of Passive Millimeter Wave System Performance in Adverse Weather Conditions

  • Type: Full Length Conference Paper
  • Authors: N. Gopalsami, S. Liao, T. Elmer, E. R. Koehl, A. C. Raptis
  • Conference: SPIE Defense, Security, and Sensing 2012
    • Date: 2012.04.25
  • Status: Presented
  • Abstract
    • Passive millimeter wave (PMMW) imaging has shown distinct advantages for detection of terrestrial targets under optically obscuring conditions such as cloud, haze, snow, and light rain. The purpose of this paper is to evaluate the performance of a PMMW imager for terrestrial target recognition with respect to range of detection and climatic variables such as cloud, light rain, and snow. We used a dual polarization MMW radiometer in the frequency range of 70-100 GHz for the evaluation. We present experimental results and analyze the effect of weather conditions on the image quality and its polarization contrast. These results will be useful for quantitative prediction of PMMW system performance for long-range terrestrial imaging.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
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    • N. Gopalsami ; S. Liao ; T. Elmer ; E. R. Koehl ; A. C. Raptis; Evaluation of passive millimeter wave system performance in adverse weather conditions. Proc. SPIE 8362, Passive and Active Millimeter-Wave Imaging XV, 83620I (May 1, 2012); DOI: 10.1117/12.919212. (Purchase published version)

      Copyright 2012 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
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Compressive Passive Millimeter-Wave Imaging

Example reconstructed images using binary measurement matrices for the proposed Bayesian and TVAL3 methods. Credits: S. Babacan
  • Type: Full Length Conference Paper
  • Authors: Sevket Derin Babacan, Martin Luessi, Leonidas Spinoulas, Aggelos K. Katsaggelos, Nachappa Gopalsami, Thomas Elmer, Ryan Ahern, Shaolin Liao, Apostolos Raptis
  • Prepared for: 2011 IEEE International Conference on Image Processing (ICIP)
  • Status: Presented as poster
  • Abstract:
    • In this paper, we present a novel passive millimeter-wave (PMMW) imaging system designed using compressive sensing principles. We employ randomly encoded masks at the focal plane of the PMMW imager to acquire incoherent measurements of the imaged scene. We develop a Bayesian reconstruction algorithm to estimate the original image from these measurements, where the sparsity inherent to typical PMMW images is efficiently exploited. Comparisons with other existing reconstruction methods show that the proposed reconstruction algorithm provides higher quality image estimates. Finally, we demonstrate with simulations using real PMMW images that the imaging duration can be dramatically reduced by acquiring only a few measurements compared to the size of the image.
  • Download
    • (IEEE doesn't allow the published versions of articles to be posted anymore, and I don't have a final author's version of this.)

Compressive sampling in active and passive millimeter-wave imaging

  • Type: Full Length Conference Paper
  • Authors: S. Liao, T. Elmer, N. Gopalsami, A. Heifetz, and A. C. Raptis
  • Prepared for: International Conference on Infrared, Millimeter, and THz waves, IRMMW-THz 2011, Houston, TX, October 2-7, 2011.
  • Status: presented
  • Abstract
    • We have developed a compressive sampling method based on Hadamard transform for active and passive millimeter wave (mmW) imaging. Hadamard masks of subwavelength sized pixels were used for collecting spatial mmW modulated data with a single-pixel detector system. The image recconstruction from subsampled data was based on a real time, iterative interpolation relaxation technique in the Hadamard spaace. Compressive sampled active and passive imaging results show that high-fidelity images of objects may be obtained with as small as 1/9 of the data needed for a full set of acquisitions.
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    • © 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
    • download article (Author version)

Compressive sampling in passive millimeter wave imaging

Compressively sampled image of a circle with a bar across it. (Inset: Simulation)
  • Type: Full Length Conf. Paper
  • Date Cleared: 11/10/2010
  • Authors: N. Gopalsami, T. W. Elmer, S. Liao, R. Ahern, A. Heifetz, A. C. Raptis, M. Luessi, D. Babacan, A. K. Katsaggelos
  • Conference: SPIE Defense, Security, and Sensing 2011, Conference DS202: Passive Millimeter Wave Imaging Technology XIV
  • Location: Orlando World Center Marriott Resort & Convention Center, Orlando, Florida, USA.
  • Conference Date: 2011 Apr 25-29
  • Affiliations
    • ANL Divisions: NE
    • Non-ANL Affil.: Northwestern Univ.
  • Keynumbers
    • ANL Publications #: 68401
  • Abstract:
    • We present a Hadamard transform based imaging technique and have implemented it on a single-pixel passive millimeter-wave imager in the 146-154 GHz range. The imaging arrangement uses a set of Hadamard transform masks of size p x q at the image plane of a lens and the transformed image signals are focused and collected by a horn antenna of the imager. The cyclic nature of Hadamard matrix allows the use of a single extended 2-D Hadamard mask of size (2p-1) x (2q-1) to expose a p x q submask for each acquisition by raster scanning the large mask one pixel at a time. A total of N = pq acquisitions can be made with a complete scan. The original p x q image may be reconstructed by a simple matrix operation. Instead of full N acquisitions, we can use a subset of the masks for compressive sensing. In this regard, we have developed a relaxation technique that recovers the full Hadamard measurement space from sub-sampled Hadamard acquisitions. We have reconstructed high fidelity images with 1/9 of the full Hadamard acquisitions, thus reducing the image acquisition time by a factor of 9.
  • Download:
    • N. Gopalsami ; T. W. Elmer ; S. Liao ; R. Ahern ; A. Heifetz ; A. C. Raptis ; M. Luessi ; D. Babacan ; A. K. Katsaggelos; Compressive sampling in passive millimeter-wave imaging. Proc. SPIE 8022, Passive Millimeter-Wave Imaging Technology XIV, 80220I (May 25, 2011); DOI: 10.1117/12.886998.

      Copyright 2011 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
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Passive millimeter wave imaging and spectroscopy system for terrestrial remote sensing.

Passive mm wave image of a pair of scissors
  • Type: Full Length Conf. Paper
  • Date Cleared: 03/04/2010
  • Authors: Nachappa Gopalsami, Shaolin Liao, Eugene R. Koehl, Thomas W. Elmer, Alexander Heifetz, Hual-Te Chien, Apostolos C. Raptis
  • Conference: SPIE Defense, Security and Sensing 2010 (DSS 2010)
  • Location: Orlando, FL
  • Conference Date: Apr. 5-9, 2010
  • Report No.: ANL/NE/CP-66398
  • Affiliations
    • ANL Divisions: NE
  • Keynumbers
    • ANL Publications #: 66398
  • Abstract:
    • We have built a passive millimeter wave imaging and spectroscopy system with a 15-channel filter bank in the 146-154 GHz band for terrestrial remote sensing. We had built the spectroscopy system first and have now retrofitted an imaging element to it as a single pixel imager. The imaging element consisted of a 15-cm-diameter imaging lens fed to a corrugated scalar horn. Image acquisition is carried out by scanning the lens with a 2-axis translation stage. A LabVIEW-based software program integrates the imaging and spectroscopy systems with online display of spectroscopic information while the system scans each pixel position. The software also allows for integrating the image intensity of all 15 channels to increase the signal-to-noise ratio by a factor of ~4 relative to single channel image. The integrated imaging and spectroscopy system produces essentially 4-D data in which spatial data are along 2 dimensions, spectral data are in the 3rd dimension, and time is the 4th dimension. The system performance was tested by collecting imaging and spectral data with a 7.5-cm-diameter and 1m long gas cell in which test chemicals were introduced against a liquid nitrogen background.
  • Download:
    • Nachappa Gopalsami ; Shaolin Liao ; Eugene R. Koehl ; Thomas W. Elmer ; Alexander Heifetz ; Hual-Te Chien ; Apostolos C. Raptis; Passive millimeter wave imaging and spectroscopy system for terrestrial remote sensing. Proc. SPIE 7670, Passive Millimeter-Wave Imaging Technology XIII, 767003 (April 24, 2010); DOI: 10.1117/12.850123

      Copyright 2010 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
    • download Article

Data Analysis Algorithms for Flaw Sizing Based on Eddy Current Rotating Probe Examination of Steam Generator Tubes.

Representative graphics
  • Type: Full Length Conf. Paper
  • Date Cleared: 10/14/2009, 06/18/2009 (abstract)
  • Authors: Bakhtiari, S.;Elmer, T. W.
  • Conference: 6th Canadian Nuclear Society International Steam Generator Conference (program)
  • Location: Toronto, Ontario, Canada
  • Conference Date: Nov. 8, 2009 - Nov. 11, 2009
    • Presented: Paper 5.13, Wed, Nov 11, 15:05
  • Report No.: ANL/NE/CP-65290
  • Affiliations
    • ANL Divisions: NE
  • Keynumbers
    • ANL Publications #: 65290, 64504 (abstract)
  • Download:

Millimeter wave sensor for far-field standoff vibrometry.

Vibrometer setup
  • Type: Full Length Conf. Paper
  • Date Cleared: 09/05/2008, 05/12/2008 (abstract)
  • Authors: Bakhtiari, S.;Gopalsami, N.;Elmer, T. W.;Raptis, A. C.
  • Conference: 35th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE 2008)
  • Location: Chicago, IL
  • Conference Date: Jul. 20, 2008 - Jul. 25, 2008
  • Report No.: ANL/NE/CP-62458
  • Affiliations
    • ANL Divisions: NE
  • Keynumbers
    • ANL Publications #: 62458, 61637 (abstract)
    • Associated Project Reference #: 2007-113-R1, 03887-00 (abstract)
  • Download:

Surface Plasmon THz Resonators for Security Applications

Development of flaw sizing algorithms for eddy current rotating probes.

  • Type: Abstract Conf. Paper
  • Date Cleared: 04/22/2008
  • Authors: Bakhtiari, S.;Elmer, T. W.
  • Conference: EPRI 27th Steam Generator NDE Workshop
  • Location: Palm Desert, CA
  • Conference Date: Jul. 21, 2008 - Jul. 23, 2008
  • Affiliations
    • ANL Divisions: NE
  • Keynumbers
    • ANL Publications #: 61543
  • Abstract:
    • Results of recent investigations at Argonne on the development of various algorithms for sizing of flaws in steam generator tubes based on eddy current rotating probe data are presented. The research was carried out as part of the activities under the International Steam Generator Tube Integrity Program sponsored by the U.S. Nuclear Regulatory Commission. A computer-aided data analysis tool has been developed to allow off-line processing of eddy current inspection data. The main objectives have been to a) allow all data processing stages to be performed under the same user interface, b) simplify modification and testing of scripts, and c) minimize analyst intervention. The focus of most recent studies at Argonne has been on the processing of data acquired with +Point™ rotating probe. Various algorithms developed under the MATLAB™ environment for the conversion, segmentation, calibration, and analysis of data have been consolidated within a single user interface. Currently, data acquired with a number of standard eddy current test equipment are automatically recognized and converted for further processing. Under the new plugin system, user-developed scripts may be tested independent of the main code. Evaluation of the sizing algorithms so far have been based on data from tubes with machined and laboratory-produced flaws. Representative results from these studies are presented.

Passive millimeter wave sensor for remote chemical detection.

  • Type: Full Length Public Comm. (Award Entry)
  • Date Cleared: 03/13/2007
  • Authors: Gopalsami, N.;Bakhitari, S.;Raptis, A.;Elmer, T.
  • Submitted To: R&D Magazine (R&D100 Awards)
    • DVD to accompany entry
  • Affiliations
    • ANL Divisions: NE;OTT;TSD
  • Keynumbers
    • ANL Publications #: 58677

A millimeter-wave radiometer for terrestrial remote sensing of chemical plumes.

  • Type: Full Length Conf. Paper
  • Date Cleared: 11/30/2006, 04/12/2007
  • Authors: Bakhtiari, S.;Gopalsami, N.;Elmer, T.;Raptis, A. C.
  • Conference: 3rd International Conference on Electromagnetic Near-Field Characterization and Imaging (ICONIC 2007)
  • Location: St. Louis, MO
  • Conference Date: Jun. 27, 2007 - Jun. 29, 2007
  • Report No.: ANL/NE/CP-57949, ANL/NE/CP-58996
  • Affiliations
    • ANL Divisions: NE
  • Keynumbers
    • ANL Publications #: 57949, 58996
  • Misc: Used as the source for the magazine article #Covert Plant Detection

Remote detection of chemicals with passive millimeter waves.

  • Type: Full Length Conf. Paper
  • Date Cleared: 09/25/2006, 04/07/2006 (abstract)
  • Authors: Gopalsami, N.;Bakhtiari, S.;Elmer, T.;Raptis, A. C.
  • Conference Sponsor: DOE
  • Conference: SPIE Conference on Chemical and Biological Sensors for Industrial and Environmental Monitoring (program, abstracts)
  • Location: Boston, MA
  • Conference Date: Oct. 3, 2006 - Oct. 4, 2006
  • Report No.: ANL/NE/CP-119279
  • Affiliations
    • ANL Divisions: ET
  • Keynumbers
    • ANL Publications #: 57409, 56082 (abstract)
    • Other ID #s: 119279
  • Download
    • N. Gopalsami*, S. Bakhtiari, T. W. Elmer, and A. C. Raptis, "Remote Detection of Chemicals with Passive Millimeter Waves," Chemical and Biological Sensors for Industrial and Environmental Monitoring II, Steven D. Christesen, Arthur J. Sedlacek III, James B. Gillespie, Kenneth J. Ewing, Editors, PProc. of SPIE Vol. 6378, 63781A, (2006).

      Copyright 2009 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

      http://dx.doi.org/10.1117/12.690212 (Purchase published version)
    • Download Article (Author version)
  • Other Links
    • (ISBN 0-8194-6476-7)

A computer-aided analysis tool for flaw sizing based on eddy current inspection data.

  • Type: Full Length Other
  • Date Cleared: 07/07/2005, 04/01/2005 (abstract)
  • Authors: Bakhtiari, S.;Kupperman, D. S.;Elmer, T. W.
  • Conference Sponsor: EPRI/NRC
  • Conference: 24th Annual EPRI Steam Generator NDE Workshop
  • Location: San Diego, CA
  • Conference Date: Jul. 11, 2005 - Jul. 13, 2005
  • Affiliations
    • ANL Divisions: ET
  • Keynumbers
    • ANL Publications #: 53859, 53004 (abstract)
    • Other ID #s: 116561, 115802 (abstract)
  • Abstract
    • Progress to date is reported on the development of a computer-aided data analysis tool for sizing of potential flaws in steam generator tubes based on eddy-current inspection data. This work was carried out at Argonne National Laboratory as part of the activities under the Iinternational Steam Generator Tube Integrity Program, which is sponsored by the United States Nuclear Regulatory Commission. A MATLAB-based graphical user interface (GUI) and the associated software have been implemented for off-line manipulation of eddy-current inspection data collected with standard test instruments and acquisition software. Both one- and two-dimensional data may be analyzed once they are converted into proper format. Data segments can be superimposed for simulating first-order interaction of signals with nearby artifacts and noise. Various routines developed earlier at Argonne for the processing of rotating pancake coil data have been incorporated into the software. Additional routines have also been developed to allow processing of data from other probes that are used for field inspections. The initial focus of this work is on automatic sizing of flaws using +Point™ data. The ultimate goal is to be able to compare the estimates of flaw size based on data from different probes. The GUI provides a convenient tool for the evaluation of user-developed algorithms. New scripts can be linked and executed using the interface dialogue box. The results may be examined at any stage of the process by using the available measurement and visualization options.
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Microwave dielectric spectroscopy of gases.

Analysis of Cerrobend Activation Produced by a 250-MeV Medical Proton Accelerator

Other

Application of computerized data screening to automated analysis of bobbin probe inspection data from SG mock-up.

  • Type: Conf. Presentation
  • Date Cleared: 04/19/2010 (Abstract)
  • Authors: Bakhtiari, S. Elmer, T. W. Shack, W. J.
  • Conference: EPRI 29th Annual Steam Generator Workshop
  • Location: Vail, CO
  • Conference Date: Jul. 12, 2010 - Jul. 13, 2010
  • Affiliations
    • ANL Divisions: NE
  • Keynumbers
    • ANL Publications #: 66605

Covert Plant Detection

Article in Nuclear Engineering International

Millimeter-wave radar sensing of airborne chemicals.

  • Type: Full Length Journal Article
  • Date Cleared: 07/30/2099
  • Authors: Gopalsami, N.;Raptis, A. C.
    • (T Elmer III [sic] is listed in the Acknowledgment section, since I created the plots for the paper.)
  • Submitted To: IEEE Trans. Microwave Theory Tech.
  • Published In: IEEE Trans. Microwave Theory Tech.
  • Affiliations
    • ANL Divisions: ET
  • Keynumbers
    • ANL Publications #: 33492
    • Other ID #s: 099679, P45245

Other Media

  • PMMWS media page
    • Contains other media, such as our CNN and radio interviews, Newspaper article, etc.

Pending

Inspection Reliability Assessments Associated with Steam Generator Tube U-bend Degradations

  • Type: Conference Abstract
  • EPRI 31st Annual Steam Generator Nondestructive Evaluation Workshop, July 9–11, 2012, Bretton Woods, New Hampshire

A Novel Interferometric Millimeter Wave Doppler Radar Architecture

  • Type: Full Length Conference Paper
  • 2013-05 I2MTC 2013 conference paper

A Novel Interferometric Sub-THz Doppler Radar with a Continuously Oscillating Reference Arm

  • Type: Full Length Journal Article
  • THz Science and Technology, IEEE Transactions on

Remote sensing of heart rate using millimeter-wave interferometry and probabilistic interpolation

  • Type: Full Length Journal Article
  • Authors: Ilya V. Mikhelson, Sasan Bakhtiari, Thomas W. Elmer, Shaolin Liao, Alan V. Sahakian
  • SPIE Journal of Biomedical Optics

Rejected

Millimeter-wave I-Q sensor for biometrics applications

  • Type: Full Length Conference Paper
  • Authors: S. Liao*, S. Bakhtiari, T. Elmer, and A. C. Raptis
  • Submitted To: Biometric Technology for Human Identification IX conference
  • Reason for rejection: Confusion over deadline dates between a specific section and the entire conference led to only an abstract being submitted when the section required a full paper by a certain deadline as well.

To Do

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