January 2004 Chuck DiMarzio, Northeastern University ECEU692 Subsurface Imaging Course Notes Part 3: Imaging with Light (2) Hyperspectral Imaging Profs. Brooks and DiMarzio Northeastern University Spring 2004

January 2004 Chuck DiMarzio, Northeastern University Hyperspectral Imaging Concepts Absorption Spectroscopy Scattering Reflectance Spectroscopy Imaging Hyperspectral Imaging The Data Cube ER-2 AVIRIS

January 2004 Chuck DiMarzio, Northeastern University Beer’s Law

January 2004 Chuck DiMarzio, Northeastern University Sample Absorption Spectra Data from Van Assendelft, O. W., Spectrophotometry of Haemoglobin Derivatives, Springfield, IL: Thomas, Graph by DiMarzio, Warner, Dwyer, Northeastern University, Hb HbO 2  a Specific Absorption, /cm /M, Wavelength, nm

January 2004 Chuck DiMarzio, Northeastern University Light in a Turbid Medium Specular Components –Fresnel Coefficients –Beer’s Law Diffuse Components –More Complicated Some Examples –Paint –Clouds

January 2004 Chuck DiMarzio, Northeastern University Reflectance Spectroscopy; Weak Scattering

January 2004 Chuck DiMarzio, Northeastern University A Simple Model  a ( 1 )=C 1  1 ( 1 )+ C 2  2 ( 1 )  a ( 2 )=C 1  1 ( 2 )+ C 2  2 ( 2 ) Two Measurements, Two Equations, and Two Unknowns Later, Prof. Brooks will talk about inverting these equations

January 2004 Chuck DiMarzio, Northeastern University Reflectance Spectroscopy; Strong Scattering

January 2004 Chuck DiMarzio, Northeastern University Pulse Oximeter 2 LED’s –Different IR Wavelengths DC Components –Total Hb, HbO 2, Other Absorbers Pulsatile Component –Arterial Hb, HbO 2

January 2004 Chuck DiMarzio, Northeastern University Hyperspectral Imaging Overview Definition (Multi-, Hyper, Ultra-Spectral) The Data Cube Image Acquisition Hardware, Data Visualization HOSIS - Hyperspectral Oxygen Saturation Imaging System: –CCD –Lyot Filter –Digital Imaging

January 2004 Chuck DiMarzio, Northeastern University Hyperspectral Imaging Definitions? –Imaging in multiple bands with width less than (10%?) of the center frequency –Imaging in more than (25?) bands –Imaging in Contiguous Bands x y The Hyperspectral “Data Cube”

January 2004 Chuck DiMarzio, Northeastern University Hyperspectral Imaging Hardware Concepts (1) Camera Coordinates are Spatial Successive Images are Different Wavelengths Tunable Filter B/W Camera x y

January 2004 Chuck DiMarzio, Northeastern University Hyperspectral Imaging Hardware Concepts (2) Pushbroom Scan –Airborne or Vehicle Mounted? –Camera Coordinates are y, –Successive Scans are Different values of x x y

January 2004 Chuck DiMarzio, Northeastern University HOSIS Instrumentation Block Diagram Computer System with Video Board Processed Images Tunable Filter See Supplementary Notes CCD Camera Halogen Lamp Target Tissue Thanks to Peter Dwyer at Lucid Technologies, MGH, and NU

January 2004 Chuck DiMarzio, Northeastern University Quantitative Imaging Quantitative Calculations –Difficult –Subject to Change Calibration Standards –Light Level –Reflectance Sources of Variation –Light Source –Camera Sensitivity –Filter Losses –Geometry –Atmosphere? –Other?