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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.
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ECEG287 Optical Detection Course NotesPart 2: Radiometry Profs. Charles A. DiMarzio and Stephen W. McKnight Northeastern University, Spring 2004 Chuck DiMarzio, Northeastern University
Topic Outline • Radiometric Quantities and Units • Radiance Theorem • Black-Body Spectrum • Some Radiance/Irradiance Values • A Little about Color Chuck DiMarzio, Northeastern University
Radiometric Quantities Chuck DiMarzio, Northeastern University
Radiometry and Photometry M, Flux/Proj. Area Notes: Spectral x=dx/dn or dx/dl: Add subscript n or w, divide units by Hz or mm. F, Flux Radiant Flux Watts Luminous Flux Lumens Radiant Exitance Watts/m2 Luminous Flux Lumens/m2=Lux 1 W is 683 L at 555 nm. Radiance Watts/m2/sr Luminance Lumens/m2/sr 1 Lambert= (1L/cm2/sr)/p I, Flux/W L,Flux/AW Radiant Intensity Watts/sr Luminous Intensity Lumens/sr E, Flux/Area Rcd. Irradiance Watts/m2 Illuminance Lumens/m2=Lux 1 ftLambert= (1L/ft2/sr)/p 1mLambert= (1L/m2/sr)/p 1 Ft Candle=1L/ft2 1 Candela=1cd=1L/sr Chuck DiMarzio, Northeastern University
The Radiance Theorem n2 n1 dW2 dA q2 q1 dW1 Chuck DiMarzio, Northeastern University
Radiance in Images dA2 dA’ dA1 dW2 dW1 z Chuck DiMarzio, Northeastern University
Resonant Cavity Modes Chuck DiMarzio, Northeastern University
Resonant Frequencies in Cavity ny nx nz Chuck DiMarzio, Northeastern University
Counting the Modes ny nx nz Chuck DiMarzio, Northeastern University
Energy per Mode (1) Chuck DiMarzio, Northeastern University
Energy per Mode (3) Chuck DiMarzio, Northeastern University
Total Spectral Energy Chuck DiMarzio, Northeastern University
Black Body Radiance (1) A’ A Chuck DiMarzio, Northeastern University
Black Body Radiance (2) A’ A Chuck DiMarzio, Northeastern University
Spectral Radiant Exitance (1) z dq q y df f x Chuck DiMarzio, Northeastern University
Spectral Radiant Exitance (2) Chuck DiMarzio, Northeastern University
Black-Body Equation (1) Chuck DiMarzio, Northeastern University
m 10 10 m / 2 5 10 , Spectral Radiant Exitance, W/m 0 10 -5 10 -10 10 l M -1 0 1 2 10 10 10 10 l m , Wavelength, m Black Body Equations (2) 10000 5000 2000 500 1000 T=300k Chuck DiMarzio, Northeastern University
Solar Irradiance on Earth Data from The Science of Color, Crowell, 1953 3000 Exoatmospheric filename=m1695.m Sea Level 2 5000 K Black Body Normalized to 1000 W/m 2500 2 6000 K Black Body Normalized to 1560 W/m m m / 2 2000 1500 , Spectral Irradiance, W/m 1000 l E 500 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 l , Wavelength, nm Chuck DiMarzio, Northeastern University
6000K Sun 6.9 G Lux Visible Sunlit Cloud 6.9 k Lux Near IR Mid IR Blue Sky 300K night sky Far IR Typical Outdoor Radiance Levels Ultraviolet Atmospheric Passbands Chuck DiMarzio, Northeastern University
T = 300 K 1 /Delta T 0.5 l M D 0 -1 0 1 2 10 10 10 10 T = 500 K 6 /Delta T 4 l 2 M D 0 -1 0 1 2 10 10 10 10 l m , Wavelength, m Thermal Imaging Chuck DiMarzio, Northeastern University
Luminance and Radiance 1.8 This curve shows the relative sensitivity of the eye. To convert to photometric units from radiometric, multiply by 683 Lumens Per Watt y 1 Photopic Sensitivity 0 400 500 600 700 800 Wavelength, nm Chuck DiMarzio, Northeastern University
Some Typical Luminance And Radiance Levels Chuck DiMarzio, Northeastern University
Emissivity Chuck DiMarzio, Northeastern University
z y x Color: Tristimulus Values • Describe Eye’s Response to Color • Based on Color Matching Experiments • Small Number of Observers • Lines are Approximations 2 1.8 1.6 1.4 1.2 1 Tristimulus Value 0.8 0.6 0.4 0.2 0 300 350 400 450 500 550 600 650 700 750 800 Wavelength, nm Chuck DiMarzio, Northeastern University
1.8 z y x Tristimulus Value 1 0 400 500 600 700 800 Wavelength, nm Characterizing Colors Object Spectrum y x Chuck DiMarzio, Northeastern University
Recording and Generating Color Images Three Separate Registered Images Object Display with Three Sources Camera with Three Filters Eye Chuck DiMarzio, Northeastern University