eceg287 optical detection course notes part 2: radiometry
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ECEG287 Optical Detection Course Notes Part 2: Radiometry. Profs. Charles A. DiMarzio and Stephen W. McKnight Northeastern University, Spring 2004. Topic Outline. Radiometric Quantities and Units Radiance Theorem Black-Body Spectrum Some Radiance/Irradiance Values A Little about Color. - PowerPoint PPT PresentationTRANSCRIPT
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-1
ECEG287 Optical Detection Course Notes
Part 2: Radiometry
Profs. Charles A. DiMarzio
and
Stephen W. McKnight
Northeastern University, Spring 2004
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-2
Topic Outline
• Radiometric Quantities and Units
• Radiance Theorem
• Black-Body Spectrum
• Some Radiance/Irradiance Values
• A Little about Color
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-3
Radiometric Quantities
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-4
Radiometry and Photometry, Flux M, Flux/Proj. Area
I, Flux/ L,Flux/AE, Flux/Area Rcd.
Radiant FluxWattsLuminous FluxLumens
Radiant ExitanceWatts/m2
Luminous FluxLumens/m2=Lux
A /
RadianceWatts/m2/srLuminanceLumens/m2/sr1 Lambert=(1L/cm2/sr)/
1 ftLambert= (1L/ft2/sr)/1mLambert= (1L/m2/sr)/
Radiant IntensityWatts/srLuminous IntensityLumens/sr
1 Candela=1cd=1L/sr
/
IrradianceWatts/m2
IlluminanceLumens/m2=Lux
1 Ft Candle=1L/ft2
Notes: Spectral x=dx/d or dx/d: Add subscript or , divide units by Hz or m.
1 W is 683 L at 555 nm.
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-5
The Radiance Theorem
1
2
n1n2
dA
d1
d2
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-6
Radiance in Images
dA’
d1
d2
dA1
dA2
z
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-7
Resonant Cavity Modes
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-8
Resonant Frequencies in Cavity
nx
nz
ny
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-9
Counting the Modes
nx
nz
ny
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-10
Energy per Mode (1)
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-11
Energy per Mode (3)
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-12
Total Spectral Energy
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-13
Black Body Radiance (1)
A
A’
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-14
Black Body Radiance (2)
A
A’
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-15
Spectral Radiant Exitance (1)
x
y
z
d
d
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-16
Spectral Radiant Exitance (2)
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-17
Black-Body Equation (1)
10-1
100
101
102
10-10
10-5
100
105
1010
, Wavelength, m
M,
Sp
ectr
al
Ra
dia
nt
Exi
tan
ce,
W/m
2/
m
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-18
Black Body Equations (2)
10-1
100
101
10210
-10
10-5
100
105
1010
, Wavelength, m
M,
Spe
ctra
l Rad
ian
t Exi
tan
ce, W
/m2 /
m
T=300k
500
1000
2000
5000
10000
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-19
Solar Irradiance on Earth
0 200 400 600 800 1000 1200 1400 1600 1800 20000
500
1000
1500
2000
2500
3000Data from The Science of Color, Crowell, 1953
, Wavelength, nm
E
, S
pe
ctra
l Irr
ad
ian
ce,
W/m
2/
m
Exoatmospheric filename=m1695.mSea Level
5000 K Black Body Normalized to 1000 W/m2
6000 K Black Body Normalized to 1560 W/m2
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-20
Typical Outdoor Radiance Levels
VisibleNear IR
Mid IRFar IR
Atmospheric Passbands
Ultraviolet6000K Sun6.9 G Lux
SunlitCloud6.9 k Lux
BlueSky 300K
night sky
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-21
Thermal Imaging
M
/Del
ta T
10-1
100
101
1020
0.5
1
T = 300 K
10-1
100
101
1020
2
4
6
, Wavelength, m
M
/D
elta
TT = 500 K
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-22
Luminance and Radiance
400 500 600 700 8000
1
1.8
Wavelength, nm
Ph
oto
pic
Se
nsi
tivity
yThis curve shows the relative sensitivity of the eye. To convert to photometric units from radiometric, multiply by 683 Lumens Per Watt
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-23
Some Typical Luminance And Radiance Levels
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-24
Emissivity
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-25
Color: Tristimulus Values
Wavelength, nm
Tris
timu
lus
Va
lue
• Describe Eye’s Response to Color
• Based on Color Matching Experiments
• Small Number of Observers
• Lines are Approximations
300 350 400 450 500 550 600 650 700 750 8000
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
zy
x
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-26
Characterizing Colors
400 500 600 700 8000
1
1.8
Wavelength, nm
Tris
timu
lus
Va
lue
z
xy
ObjectSpectrum
x
y
dLxX
0
ˆ
ZYX
Xx
Jan 2004 Chuck DiMarzio, Northeastern University 10464-2-27
Recording and Generating Color Images
Camerawith
ThreeFilters
Displaywith
ThreeSources
Eye
ObjectThree SeparateRegistered Images