Standoff Human Life Sign Detection using High Sensitivity Pulsed Laser Vibrometer

Transcription

1 Standoff Human Life Sign Detection using High Sensitivity Pulsed Laser Vibrometer Chen-Chia Wang, Sudhir Trivedi, and Feng Jin Brimrose Corp. of America, 7720 Belair Road, Baltimore, MD V. Swaminathan, Sheela Nagaraj, and Shafik Quoraishee US Army, RDECOM-ARDEC, Picatinny, NJ Narasimha S. Prasad NASA Langley Research Center, Mail Stop 468, Hampton, VA

2 Acknowledgement Financial supports by: NASA Langley US Army NightVision Lab US Army Picatinny (NJ) 2

3 OUTLINS 1. Once upon a time.. 2. Sensor Physics 3. Monitoring of Biological Life Signs 4. Conclusions 3

4 Buried Landmine Detection : Laser Vibrometer Vehicle-Mounted Lasers or Acoustic Speakers Excite Acoustic/Seismic Wave Propagation Laser Doppler Vibrometer (vehicle-mounted) Monitors Ground Vibration Presence of Mines Causes Resonance at Certain Frequencies Laser Vibrometer ( Conferences/Monterey2/LAND/ XIANG.PDF) Excitation ( TechnicalReps/Day1/Goggans/ GoggansSlidesFinal.pdf) Ground mine 4

5 Laser Vibrometer Killer : Optical Speckles 1 mm Limited Sensitivity ~ 1 nm in surface displacement 5

6 Solution: Photo-EMF Pulsed Laser Vibrometer (PPLV) Amplifier Photo-EMF Sensor 10 mm Electrodes Excellent Sensitivity ~ pm resolution in surface displacement Optical Speckle Tolerant 6

7 Schematic of Experimental Arrangement E LO e jk LO r. LOt jk S E e. S r St - + Optical Motion Sensor Non-Parallel Incident Laser Beams, Intersection Angle ~ 1 o II-VI Semiconductor-Based & Grown by Brimrose 7

8 PPLV for Vibration Sensing Beam Splitter Vibration Source Pulsed Laser Lens Target Mirror 2 Lens Photocurrent sensor Vibration causes Doppler shift in frequency 8

9 Surface Vibration : 10 khz, 1 nm Displacement Pulsed Vibrometer Output (V) Time (micro-second) 9

10 PPLV : High Sensitivity and Speckle Tolerant Aluminum surface 600 Hz grit sandpaper 400 Hz 1 mm Spectrum (dbv) Hz Spectra (dbv) Hz Frequency (Hz) Frequency (Hz) sinusoidal vibrations with 75 pm displacement 120 pm displacement Soldier surface could be contaminated with blood, sweat, grease, dirt.etc 10

11 Contact-less/Remote Biological Life Signs Detection War fighting, Biological-, chemical-, radiation-attack scenarios Medical operations/treatments, non-contact ECG/EKG Challenges facing conventional technologies Wired approach Requires access to specific parts of the subject s body: chest or carotid Conventional laser vibrometers : Speckle-intolerant, limited sensitivity, Requires surface pre-treatments/retro-reflective tapes Microwave : Limited resolution/sensitivity, abundant ground clutter 11

12 PPLV to the Rescue : Contact-less Good Sensitivity : Applies to essentially any part of the subject s body Sensitivity better than 75 pm in surface displacement Speckle-tolerant : No need for skin exposure, No surface pre-treatment, Detection from the surface of clothing 12

13 Experimental Setup Beam Splitter Pulsed Laser Lens Mirror 2 Lens Photocurrent Photo-EMF sensor 13

14 Detected Life Signs from Human Subjects Heartbeat Exhaling Inhaling Heartbeat Ex In Heartbeat Breathing/Gasping Heartbeat Exhaling 14

15 Deceased Albino House Mouse : Featureless Temporal Trace 6 Photo-EMF Pulsed Laser Vibrometer Output (V) Time (second) 15

16 Individual Pulses / Study of Heart Movement/Cardiac Events Photo-EMF Pulsed Laser Vibrometer Output (V) Time (sec) Accelerometer reading Interrogation point Comparison with ECG/EKG is warranted. 16

17 FFT Determines Heartbeat Rates 3 x Estimated Heartbeat Rate : 75 bpm Heartbeat Spectrum (a.u.) Frequency (Hz) 17

18 Blood Circulation Conditions to the Extremities Applied Pressure (mmhg) Photo-EMF Pulsed Laser Vibrometer Output (V) Time (sec) Interrogation point Restriction of blood flow reduces strength of heartbeat 18

19 Most Recent Results from Female Human Subject, 1 meter Standoff Distance 1.3 x 104 Filtered time traces Signal amplitude (A.U.) Heartbeat #1 Heartbeat #2 Heartbeat # Time (sec) PPLV sees vivid, detailed movements of the heartbeat cycle, REMOTELY 19

20 Most Recent Results from Female Human Subject, 1 meter Standoff Distance 1.2 x ventricles 104 Trace from shin contraction Atria contraction 1.19 pulmonary valve closure PPLV output signal (A.U.) Cardiac cycle Cardiac cycle Time (sec) AV valves closure Aorta valve closure SPECULATON on peak assignments 20

21 Most Recent Results from Male Human Subject, 1 meter Standoff Distance 1.59 x Cardiac cycle Trace from Upper Thigh Cardiac cycle PPLV output signal (A.U.) Time (sec) Data taken from grey-color PJ pants, heartbeat rate in the 50 s bpm 21

22 Conclusions PPLV non-contact life signs determination Surface quality independent Detailed info on cardiac events? 22