ECEU692 Subsurface Imaging Course Notes Part 14: A Pause to Reflect

1. ECEU692Subsurface ImagingCourse NotesPart 14: A Pause to Reflect Profs. Brooks and DiMarzio Northeastern University Spring 2004 Chuck DiMarzio, Northeastern University

2. From Our First Lecture... • Some Examples • Some Technologies • NSF Center; CenSSIS at NU • Taxonomies and Architectures of the Field Chuck DiMarzio, Northeastern University

3. Some SSI Examples • Landmine Detection [Acoustic, GPR,EM, NQR] • Tunnel and Bunker Detection [Acoustic,GPR,EM] • Excavation Planning [Acoustic,GPR,EM] • Luggage Screening [X-Ray,NQR] • Ocean Imaging [HSI] • Breast Tumor Detection and Classif.[X-Ray,US, DOT] • Stroke Differentiation [DOT, MRI] • Functional Brain Imaging [DOT, MRI] • Cardiac Imaging [Ultrasound, EKG] • Retinal Imaging [HSI, Vis] • Vulnerable Plaque in Coronary Artery [Vis, US, OCT] • Fetal Imaging [DOT, Ultrasound] Chuck DiMarzio, Northeastern University

4. Model Subsurface Problems • Problem Geometry • A* Looking through one material to see another which is below it. • B* Looking through one material to find inhomogeneities in it. • Application Areas • 1* Air/Space, 2* Terrestrial, 3* Ocean, 4* Medical, 5* Biological * Letters and Numbers Refer to Next Slide Chuck DiMarzio, Northeastern University

5. Model Subsurface Problems 1 Air/Space 2 Terestrial 3 Ocean 4 Medical 5 Biological ICM Cell Counting Excavation Planning Dermatology Seabed Mapping Landuse CORAL REEFS A Mapping Mitochondria Functional Brain Mapping Pollution Mapping Landmine Detection Atmospheric Gasses River Plume B Chuck DiMarzio, Northeastern University

6. Example Problems for the Course • Geometries • Semi-Infinite Slab Lab in HW2 • Two-Layers HW3 • Embedded Object Lab in HW4 • SSI Technology • Hyperspectral Imaging Lab in HW2 • Coursework • Experiments • Analysis Chuck DiMarzio, Northeastern University

7. Some SSI Technologies • X-Ray • Light (UV, Visible, Infrared) • Ground-Penetrating Radar • Electrical Impedance Tomography • Magnetic Resonance Imaging • Acoustics and Ultrasound • Electromagnetic Sensors • Passive Electromagnetic Imaging • Seismics • Others ~Wavelength Chuck DiMarzio, Northeastern University

8. Different Types of Waves 8 10 Light (Real) 1mm mm 6 10 -1 4 10 DPDW mm 1mm Sound ), Wavenumber, m (Imag) (Imag) cm 2 10 1m p (Real) m 0 k/(2 10 -2 10 1km km 10059_1 -4 10 0 5 10 15 20 10 10 10 10 10 f, Frequency, Hz. Chuck DiMarzio, Northeastern University

9. Wave Behavior • Absorption • Reflection • Refraction • Diffraction • Interference • Scattering 10471-15-1.jpg Thanks to Emmanuel Bossy, BU Remember HW 1? Chuck DiMarzio, Northeastern University

10. Light in Skin and More Optical Imaging Diffusive Imaging NIR NIR Vis Vis Stratum Corneum, 5-10mm keratinocytes Epidermis, 50-100mm melanocytes Basal cell cancer (RCM) Dermis, few mm collagen and elastin Chuck DiMarzio, Northeastern University

11. Probe system Detector system 1. Definition & Scope of SSI Probe(s) 1 2 .. I 1 2 .. J Detector(s) One or more probes transmit one or more waves, which are launched into the medium after processing by some probe system. The waves are characterized by their location, power, frequency, waveform, polarization, etc One or more detectors characterized by their location, sensitivity, or noise, detect the waves after processing by some detector system Medium object Medium & object are characterized by physical properties, to which the probe waves are sensitive. Thanks to Prof. Bahaa Saleh, Chair of ECE at Boston University for the concept for this and following slides. Chuck DiMarzio, Northeastern University

12. Examples of wave-dependent properties Optical Electromagnetic X-Ray • Refractive index • Absorption coeff. • Fluorescence • Dielectric constant • Conductivity • Nuclear spin • Absorption Particle Beams Electron,Positron,.. Electrical/Magnetic Acoustic • Scattering • Emission of x-ray or • secondary emission • Density • Compressibility • Conductivity • Permeability Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh

13. Goals of SSI Examples of Underlying Parameters • Estimate • Distribution of Measured Parameters or • Underlying Parameters Related to Them, or • Object Shape or Features or • Detect the Presence of a Target or • Classify Objects Based on Measured Parameters • Density, Porosity, Stiffness • Chemical composition, pH • Metabolic information • Ion concentration • Physiological changes (e.g., oxygenation) • Extrinsic markers (dyes, chemical tags) Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh

14. Probes Detectors Surface Taxonomy of SSI . Medium object Object Medium Probe Optical/IR Electro- magnetic Fluorescence Absorption Acoustic X-ray Absorption Nonlinear Absorption Dispersion CW Modulated Pulsed Nonlinear Scattering Scattering Scattering Partially Coherent Multi- Spectral Coherent Diffusion Diffusive Phase Object Clutter Quantum Classical Depolarizing Inhomogeneous/ Layered Outside Inside Auxiliary Moving Stationary Rough Surface Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh Thanks to Prof. Bahaa Saleh

15. Architectures of SSI Transmitter (Probe) & Receiver (detector) Patterns i j j i Probe Pattern: Region in the medium occupied by the probe wave, in the absence of the target & clutter Detector Pattern: Region in the medium to which the detector is sensitive, I.e., , if a source were to exist within this medium, it would be detected. Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh

16. MVT LP Localized vs Tomographic SSI Localized SSI Tomograhic SSI 1 2 .. I 1 2 .. J 1 2 .. I 1 2 .. J Probe System Detector System Probe System Detector System j j i i ij ij Interaction regions {ij}are small & do not overlap significantly Interaction regions {ij}are large & do overlap significantly Interaction region Vij = region in the medium to which the signal of detector j is sensitive, when probe wave i is active Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh

17. LP Example i) Distributed Probe/ Localized Detection Transverse Gazing Axial Scanning Transverse Scanning Axial Scanning Example: Photography Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh

18. LP Example ii) Localized probe/ distributed (bucket) detection Two-Photon Scanning Laser Microscopy Good transverse resolution Poor axial resolution Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh

19. LP Example iii) Confocal probe and detection Both axial & transverse resolution Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh

20. LP Example iv) Pulsed Coaxial probe and detection Transverse resolution by scanning Axial resolution by time of flight sectioning Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh

21. MVT Example v) Axial Tomography Computed transverse & axial resolution Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh

22. Example vi) Diffusive Photon Density Waves Transmission Reflection Generally poor axial and transverse resolution Chuck DiMarzio, Northeastern University Thanks to Prof. Bahaa Saleh

23. Example vii) Time-Domain Photon Migration Transmission Reflection Generally poor axial and transverse resolution Chuck DiMarzio, Northeastern University

24. Why Did We Choose What We Did? • It’s at least somewhat representative of the scope of SSI • We know it well • It allows you to explore problems in depth • It allows you to do some experiments in our labs Chuck DiMarzio, Northeastern University