January 2003 Chuck DiMarzio, Northeastern University 10471-1a-1

ECEU692Subsurface Imaging

Course NotesPart 1: Introduction to SSI

Profs. Brooks and DiMarzio

Northeastern University

Spring 2004

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-2

Lecture 1 Overview

• Administrivia– Syllabus and Contact Information– Course Requirements– Web Page and E-mail list– Presentation Material

• Introduction to Subsurface Imaging

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-3

Course and Contact Information

• Course Website– http://www.ece.neu.edu/courses/eceu692/2004sp

• Instructors– Dana Brooks

• mailto:brooks@ece.neu.edu

• Phone 617-373-3352

– Chuck DiMarzio• mailto:dimarzio@ece.neu.edu

• Phone 617-373-2034

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-4

Subsurface Sensing and Imaging

• Some Examples

• Some Technologies

• NSF Center; CenSSIS at NU

• Taxonomies and Architectures of the Field

• Literature

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-5

Some SSI Examples• Landmine Detection• Tunnel and Bunker Detection• Excavation Planning• Luggage Screening• Ocean Imaging• Breast Tumor Detection and Classification• Stroke Differentiation• Functional Brain Imaging• Cardiac Imaging• Retinal Imaging• Vulnerable Plaque in Coronary Artery• Fetal Imaging

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-6

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

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-7

Model Subsurface Problems1 Air/Space 3 Ocean2 Terestrial 4 Medical 5 Biological

Landuse

AtmosphericGasses

LandmineDetection

Pollution Mapping

Dermatology

FunctionalBrain Mapping

ExcavationPlanning

MappingMitochondria

ICM CellCounting

A

B

CORAL CORAL REEFSREEFS

SeabedMapping

River River PlumePlume

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-8

Example Problems for the Course

• Geometries– Semi-Inifinite Slab– Two-Layers– Embedded Object

• SSI Technology– Hyperspectral Imaging

• Coursework– Experiments– Analysis

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-9

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

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-10

CenSSISNSF and Industry

Support

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-11

Probe system

1. Definition & Scope of SSIProbe(s) 1 2 .. I

Medium & object are characterized by physical properties, to which the probe waves are sensitive.

One or more probestransmit one or more waves, which are launched into themedium after processing by some probe system.The waves are characterized by their location, power, frequency, waveform, polarization, etc

One or more detectorscharacterized by theirlocation, sensitivity, or noise, detect the waves after processingby some detector system

1 2 .. J Detector(s)

Detector system

objectMedium

Thanks to Prof. Bahaa Saleh, Chair of ECE at Boston University for the concept for this and following slides.

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-12

Examples of wave-dependent properties

• Density• Compressibility

Acoustic

• Dielectric constant• Conductivity• Nuclear spin

Electromagnetic

• Refractive index• Absorption coeff. • Fluorescence

Optical

• Absorption

X-Ray

Electrical/Magnetic

• Conductivity• Permeability

Particle BeamsElectron,Positron,..

• Scattering• Emission of x-ray or• secondary emission

Thanks to Prof. Bahaa Saleh

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-13

Density, Porosity, Stiffness Chemical composition, pH Metabolic information Ion concentration Physiological changes (e.g., oxygenation) Extrinsic markers (dyes, chemical tags)

Examples of Underlying Parameters

Goals of SSI• 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

Thanks to Prof. Bahaa Saleh

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-14

Rough Surface

Inhomogeneous/Layered

MediumMedium

Absorption

Dispersion

Scattering

Diffusion

Clutter

Electro-magnetic

Optical/IR

X-rayAcoustic

CW Pulsed Modulated

CoherentMulti-

Spectral

Classical Quantum

Outside Inside Auxiliary

PartiallyCoherent

ObjectObject

Nonlinear Absorption

ScatteringNonlinear Scattering

DiffusivePhase Object

Depolarizing

Stationary Moving

Absorption Fluorescence

ProbeProbe

Taxonomy of SSI .object

Medium

Surface

Probes Detectors

Thanks to Prof. Bahaa SalehThanks to Prof. Bahaa Saleh

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-15

i

ij

Transmitter (Probe) & Receiver (detector) Patterns j

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.

Architectures of SSI

Thanks to Prof. Bahaa Saleh

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-16

1 2 .. I 1 2 .. J

Probe System

Detector System

Interaction regions {ij} are small & do not overlap significantly

Localized SSI Tomograhic SSI

i j

ij

1 2 .. I 1 2 .. J

Probe System

Detector System

i j

ij

LP MVT

Interaction region Vij = region in the medium to which the

signal of detector j is sensitive, when probe wave i is active

Interaction regions {ij} are large & do overlap significantly

Localized vs Tomographic SSI

Thanks to Prof. Bahaa Saleh

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-17

Transverse ScanningAxial Scanning

Transverse GazingAxial Scanning

Example i) Distributed Probe/ Localized Detection

LP

Thanks to Prof. Bahaa Saleh

Example: Photography

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-18

Good transverse resolution Poor axial resolution

LP

Example ii) Localized probe/ distributed (bucket) detection

Thanks to Prof. Bahaa Saleh

Two-Photon ScanningLaser Microscopy

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-19

Both axial & transverse resolution

LP

Example iii) Confocal probe and detection

Thanks to Prof. Bahaa Saleh

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-20

Transverse resolution by scanningAxial resolution by time of flight sectioning

Example iv) Pulsed Coaxial probe and detection

LP

Thanks to Prof. Bahaa Saleh

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-21

Computed transverse & axial resolution

MVT

Example v) Axial Tomography

Thanks to Prof. Bahaa Saleh

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-22

Generally poor axial and transverse resolution

Example vi) Diffusive Photon Density Waves

Thanks to Prof. Bahaa Saleh

Transmission Reflection

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-23

Generally poor axial and transverse resolution

Example vii) Time-Domain Photon Migration

Transmission Reflection

January 2003 Chuck DiMarzio, Northeastern University 10471-1a-24

SSI Literature• Specialized Journals and Conferences (eg. Journal

of Biomedical Optics, ASLMS, IEEE Trans. Biomed. Eng.)

• Journals and Conferences Specific to the Application area (eg. J. Invest. Dermatology)

• Journals and Conferences Specific to the Technology area (eg. Optics Letters, IEEE Trans. Sig. Proc.)

• Recent Additions:– Journal: Subsurface Sensing Technologies and

Applications, Quarterly Since January 2000.– Conference Proceedings: SPIE, 1999, 2000, 2001