ECEU 692 Subsurface Imaging Course Notes Part 2
ECEU 692 Subsurface Imaging Course Notes Part 2: Imaging with Light (1) Profs. Brooks and Di. Marzio Northeastern University Spring 2004 January 2004 Chuck Di. Marzio, Northeastern University 1
Lecture Overview • • • Optical Spectrum and Sources Interaction of Light with Matter A Bit of Geometric Optics A Bit of Physical Optics Microscopes (1) – Point-Spread Function – Optical Transfer Function • Detectors and Cameras January 2004 Chuck Di. Marzio, Northeastern University 2
Classical Maxwellian EM Waves Thanks to Prof. S. W. Mc. Knight v=c λ E H x E z H E H λ=c/υ y c=3 x 108 m/s (free space) υ = frequency (Hz) January 2004 Chuck Di. Marzio, Northeastern University 3
Electromagnetic Spectrum (by λ) UV= Near-UV: 0. 3 -. 4 μ Vacuum-UV: 100 -300 nm VIS= IR= 0. 40 -0. 75μ Near: 0. 75 -2. 5μ Mid: 2. 5 -30μ Extreme-UV: 1 -100 nm 10 nm =100Å 0. 1 Å γ-Ray 0. 1 μ Far: 30 -1000μ 1μ (300 THz) 1Å 10 Å X-Ray Soft X-Ray January 2004 1 mm Mm-waves Chuck Di. Marzio, Northeastern University Thanks to Prof. S. W. Mc. Knight 10 μ 100 μ = 0. 1 mm 1 cm 0. 1 m Microwaves RF 4
Typical Outdoor Radiance Levels Ultraviolet Visible Near IR Mid IR Far IR 6000 K Sun 6. 9 G Lux Sunlit Cloud 6. 9 k Lux Blue Sky 300 K night sky Atmospheric Passbands January 2004 Chuck Di. Marzio, Northeastern University 5
D Ml/Delta T Thermal Imaging T = 300 K 1 0. 5 0 1 10 T = 500 K 10 10 2 D Ml/Delta T 0 -1 10 6 4 2 0 -1 10 January 2004 10 10 l, Wavelength, m m Chuck Di. Marzio, Northeastern University 6
Light in a Turbid Medium Input Specular Reflection Diffuse Reflection Scattering Absorption Direct Transmission Diffuse Transmission January 2004 Chuck Di. Marzio, Northeastern University 7
Example Interactions Slab Absorption and Scattering Semi-Infinite Medium January 2004 Chuck Di. Marzio, Northeastern University Two-Layer 8
Lecture Overview • • • Optical Spectrum and Sources Interaction of Light with Matter A Bit of Geometric Optics A Bit of Physical Optics Microscopes (1) – Point-Spread Function – Optical Transfer Function • Detectors and Cameras January 2004 Chuck Di. Marzio, Northeastern University 9
Camera Lens Image Location A F’ A’ F f s f’ s’ Lens Equation January 2004 Chuck Di. Marzio, Northeastern University 10
Camera Lens Magnification x A -x’ A’ s January 2004 Chuck Di. Marzio, Northeastern University s’ 11
Field of View Film= Exit Window January 2004 Chuck Di. Marzio, Northeastern University 12
Diffraction x 1 x What is the light distribution in the spot? January 2004 Chuck Di. Marzio, Northeastern University 13
Fraunhofer Diffraction January 2004 Chuck Di. Marzio, Northeastern University 14
Point Spreadand Optical Transfer Functions Fourier Transform object scale perfect image actual image January 2004 x’ SCALE PERFECT IMAGE x’ x MULT OTF ACTUAL IMAGE Chuck Di. Marzio, Northeastern University d 0 Convolve with PSF OBJECT R 15
Fraunhoffer Examples January 2004 Chuck Di. Marzio, Northeastern University 16
Coherent and Incoherent OTF • Incoherent Image – Irradiance rather than field. – PSFinc is |PSFcoh|2 • Fourier Transform – OTFinc is |OTFcoh|2 – Meaning of Phase is a bit complicated January 2004 Chuck Di. Marzio, Northeastern University 17
1 0. 9 0. 8 An Extreme Example 0. 6 0. 5 Colorbar for all Image Object 20 0. 7 40 0. 4 0. 3 0. 2 0. 1 60 20 80 40 20 100 60 40 120 80 60 140 100 80 160 120 100 180 20 40 60 80 Point-Spread Function of System January 2004 100 140 120 0 140 160 120 180 160 140 180 20 40 60 80 100 160 120 140 160 180 20 40 Chuck Di. Marzio, Northeastern University 60 80 100 120 140 18 160 180
Bright-Field Microscopy F A’ A F’ f s f’ s’ Object Plane January 2004 Image Plane Chuck Di. Marzio, Northeastern University 19
Lecture Overview • • • Optical Spectrum and Sources Interaction of Light with Matter A Bit of Geometric Optics A Bit of Physical Optics Microscopes (1) – Point-Spread Function – Optical Transfer Function • Detectors and Cameras January 2004 Chuck Di. Marzio, Northeastern University 20
Semiconductor Detector Conduction Band Absorption Emission Valence Band 10057 p 1 -2 here hn e. January 2004 Chuck Di. Marzio, Northeastern University 21
Remember N-FET Structure? S, Source G, Gate n+ D, Drain n+ Si. O 2 Insulator 20 -100 mm Channel: 2 to 500 mm into page P-Type Material NMOS Metal-Oxide-Semiconductor January 2004 B, Body Chuck Di. Marzio, Northeastern University Channel Length 1 to 10 mm 22
Charge-Coupled Device (CCD) S G D S D B Channel Length 1 to 10 mm January 2004 B ~10 mm X n. Rows Chuck Di. Marzio, Northeastern University 23
CCD Charge Transfer Clock Voltage 1 0. 9 2 Row Number 0. 8 4 0. 7 0. 6 m 10057_1. m Figure 1 6 8 0. 5 0. 4 0. 3 10 0. 2 0. 1 12 0 0. 5 V 1 1. 5 2 time, Clock Cycles V 2. 5 3 One Line Clock Signals January 2004 0 time Chuck Di. Marzio, Northeastern University 24
Computer Interfacing • Analog Camera and Frame Grabber • Digital Camera Analog Camera Computer with Frame Grabber Analog Monitor January 2004 Computer Monitor Chuck Di. Marzio, Northeastern University Computer Monitor 25
Linearity and AGC 1 • Automatic Gain Control (AGC) • Feedback Output Voltage 0. 8 0. 6 – Control G – Based on. . . 0. 4 • Peak Signal • Average Signal • Peak in a Region 0. 2 0 0 0. 2 January 2004 0. 6 Input Voltage 0. 8 1 • Not Desirable for Quantitative Work Chuck Di. Marzio, Northeastern University 26
Pixelation and Digitization 255 Count 0 “Brightness” January 2004 Chuck Di. Marzio, Northeastern University 27
Digitization and Dynamic Range 2 N-1 Saturation Maximum Signal Minimum Signal Step Size Pedestal Signal Voltage 0 January 2004 Dark Chuck Di. Marzio, Northeastern University 28
Some Standard and Extreme Parameters • VGA Frame Size: 640 by 480 – Up to 4 k Square? • Standard Update Rate: 30 Hz. Interlaced – Up To few k. Hz. • Standard Digitization: 8 Bits – Up To 12. • Pixel Size: 10 micrometers. • Color Camera: 3 Channels, 8 Bits Each January 2004 Chuck Di. Marzio, Northeastern University 29
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