ECEU692
Subsurface Imaging
Course Notes
Part 2: Imaging with Light (1)
Profs. Brooks and DiMarzio
Northeastern University
Spring 2004
January 2004
Chuck DiMarzio, Northeastern University
10471-2-1
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 DiMarzio, Northeastern University
10471-2-2
Classical Maxwellian EM Waves
Thanks to Prof. S. W.McKnight
v=c
λ
E
H
x
E
z
H
E
H
λ=c/υ
y
c=3x108 m/s (free space)
υ = frequency (Hz)
January 2004
Chuck DiMarzio, Northeastern University
10471-2-3
Electromagnetic Spectrum (by λ)
UV=
Near-UV: 0.3-.4 μ
VIS=
IR=
0.40-0.75μ
Near: 0.75-2.5μ
Vacuum-UV: 100-300 nm
Mid: 2.5-30μ
Extreme-UV: 1-100 nm
Far: 30-1000μ
0.1 μ
10 nm
=100Å
0.1 Å
1Å
γ-Ray
1μ
(300 THz)
10 Å
X-Ray Soft X-Ray
January 2004
1 mm
Mm-waves
Chuck DiMarzio, Northeastern University
Thanks to Prof. S. W.McKnight
10 μ
100 μ =
0.1mm
1 cm
0.1 m
Microwaves
10471-2-4
RF
Typical Outdoor Radiance Levels
Ultraviolet
Visible
Near IR
6000K Sun
6.9 G Lux
Sunlit
Cloud
6.9 k Lux
Blue
Sky
Mid IR
Far IR
300K
night sky
Atmospheric Passbands
January 2004
Chuck DiMarzio, Northeastern University
10471-2-5
D Ml/Delta T
Thermal Imaging
T = 300 K
1
0.5
0
1
0
1
2
10 T = 500 K 10
10
D Ml/Delta T
0 -1
10
6
4
2
0 -1
10
January 2004
10
10
l, Wavelength, m m
Chuck DiMarzio, Northeastern University
10
10471-2-6
2
Light in a Turbid Medium
Input
Specular
Reflection
Diffuse
Reflection
Scattering
Absorption
Direct Transmission
Diffuse Transmission
January 2004
Chuck DiMarzio, Northeastern University
10471-2-7
Example Interactions
Slab Absorption
Slab Absorption and
Scattering
Semi-Infinite Medium
January 2004
Chuck DiMarzio, Northeastern University
Two-Layer
10471-2-8
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 DiMarzio, Northeastern University
10471-2-9
Camera Lens Image Location
F’
A
A’
F
f
f’
s’
s
Lens Equation
January 2004
Chuck DiMarzio, Northeastern University
10471-2-10
Camera Lens Magnification
x
A
-x’ A’
s’
s
m
January 2004
x'
s'

x
s
Chuck DiMarzio, Northeastern University
10471-2-11
Field of View
Film=
Exit
Window
January 2004
Chuck DiMarzio, Northeastern University
10471-2-12
Diffraction
x1
x
What is the light distribution in the spot?
January 2004
Chuck DiMarzio, Northeastern University
10471-2-13
Fraunhofer Diffraction
January 2004
Chuck DiMarzio, Northeastern University
10471-2-14
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 DiMarzio, Northeastern University
d0
Convolve
with PSF
OBJECT
R
10471-2-15
Fraunhoffer Examples
January 2004
Chuck DiMarzio, Northeastern University
10471-2-16
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 DiMarzio, Northeastern University
10471-2-17
1
0.9
0.8
0.7
An Extreme Example
0.5
Colorbar for all
Image
Object
20
0.6
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
120
140
160
180
160
140
180
20
40
60
80
100
160
120
140
160
180
180
20
40
Chuck DiMarzio, Northeastern University
60
80
100
120
140
160
10471-2-18
180
Bright-Field Microscopy
A’
F
A
F’
f
s
f’
s’
Object
Plane
January 2004
Image
Plane
Chuck DiMarzio, Northeastern University
10471-2-19
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 DiMarzio, Northeastern University
10471-2-20
Semiconductor Detector
Conduction
Band
Absorption
Emission
Valence
Band
10057p1-2 here
hn
eJanuary 2004
Chuck DiMarzio, Northeastern University
10471-2-21
Remember N-FET Structure?
S, Source
G, Gate
n+
D, Drain
n+
SiO2 Insulator
20-100mm
Channel: 2 to 500 mm
into page
P-Type Material
NMOS
Metal-Oxide-Semiconductor
January 2004
B, Body
Chuck DiMarzio, Northeastern University
Channel Length
1 to 10 mm
10471-2-22
Charge-Coupled Device (CCD)
S
G
D
S
D
B
Channel Length
1 to 10 mm
January 2004
B
~10 mm X nRows
Chuck DiMarzio, Northeastern University
10471-2-23
CCD Charge Transfer
Clock Voltage
1
0.9
2
Row Number
0.8
4
0.7
0.6
m10057_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
0
One
Line
Clock Signals
January 2004
3
time
Chuck DiMarzio, Northeastern University
10471-2-24
Computer Interfacing
• Analog Camera and Frame Grabber
• Digital Camera
Digital Camera
Analog Camera
Computer with
Frame Grabber
Analog
Monitor
January 2004
Computer
Monitor
Chuck DiMarzio, Northeastern University
Computer
Computer
Monitor
10471-2-25
Linearity and AGC
1

y  Gx
0.8
Output Voltage
• Automatic Gain
Control (AGC)
• Feedback
  0.5
0.6
0.4
 1
– Control G
– Based on...
 2
• Peak Signal
• Average Signal
• Peak in a Region
0.2
0
0
0.2
January 2004
0.4
0.6
Input Voltage
0.8
1
• Not Desirable for
Quantitative Work
Chuck DiMarzio, Northeastern University
10471-2-26
Pixelation and Digitization
255 Count
0
“Brightness”
January 2004
Chuck DiMarzio, Northeastern University
10471-2-27
Digitization and Dynamic Range
2N-1
Saturation
Maximum
Signal
Minimum
Signal
Step Size
Pedestal
Signal Voltage
0
January 2004
Dark
Chuck DiMarzio, Northeastern University
10471-2-28
Some Standard and Extreme
Parameters
• VGA Frame Size: 640 by 480
– Up to 4k Square?
• Standard Update Rate: 30 Hz. Interlaced
– Up To few kHz.
• Standard Digitization: 8 Bits
– Up To 12.
• Pixel Size: 10 micrometers.
• Color Camera: 3 Channels, 8 Bits Each
January 2004
Chuck DiMarzio, Northeastern University
10471-2-29