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ECE-1466 Modern Optics Course Notes Part 6

ECE-1466 Modern Optics Course Notes Part 6. Prof. Charles A. DiMarzio Northeastern University Spring 2002. Lecture Overview. Some Radiometry Terminology Equations Relating Radiometric Parameters Photometric Parameters Some Numbers A Little Bit of Scattering Theory

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ECE-1466 Modern Optics Course Notes Part 6

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  1. ECE-1466Modern OpticsCourse NotesPart 6 Prof. Charles A. DiMarzio Northeastern University Spring 2002 Chuck DiMarzio, Northeastern University

  2. Lecture Overview • Some Radiometry • Terminology • Equations Relating Radiometric Parameters • Photometric Parameters • Some Numbers • A Little Bit of Scattering Theory • Some Applications in Microscopy Chuck DiMarzio, Northeastern University

  3. Radiometric Quantities Chuck DiMarzio, Northeastern University

  4. 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 Exitance 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

  5. 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

  6. Radiance in Images dA2 dA’ dA1 dW2 dW1 z Chuck DiMarzio, Northeastern University

  7. Typical Radiance Levels Our Example = 0.0037/p W/m2/sr ~ 0.001 W/m2/sr at f/1 Half-Lux Camera = 0.0044 W/m2/sr Chuck DiMarzio, Northeastern University

  8. Black-Body Equation (1) Chuck DiMarzio, Northeastern University

  9. 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

  10. 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

  11. Tungsten Lamps: Hot is Good! • 3000 K • 20 Lumens per Watt • lpeak=1.22mm • x = .4357y = .4032 z = .1610 • 3400 K note: (3400/3000)4=1.64) • 34 Lumens per Watt note: 20X1.64=33 • lpeak=1.09mm • x = .4112y = .3935 z = .1953 y x Chuck DiMarzio, Northeastern University

  12. Quartz-Halogen Lights • Tungsten Filament • Higher Temperature = Brighter, Whiter • Requires Quartz Envelope • Tungsten Evaporates More Rapidly • Halogen Catalyst • Prevents Tungsten Deposit on Hot Envelope • Tungsten Redeposits on the Filament • Evaporation and Redeposition Requires Thicker Filament • Lower Resistance Requires Lower Voltage Chuck DiMarzio, Northeastern University

  13. Lighting Efficiency 1000000 Fluorescent 94 Lumens/Watt at 7000K (Highest Efficiency Black Body) Hi Pressure Na Metal Halide 100000 Lo Pressure Na Incandescent 10000 Light Output, Lumens Thanks to John Hilliar (NU MS ECE 1999) for finding lighting data from Joseph F. Hetherington at www.hetherington.com. 10 June 1998 1000 20.7 Lumens/Watt at 3000K 100 10000 1 10 100 1000 Power Input, Watts

  14. Source Intensity 0.142 W • Fraction of Light in Filter Passband • Given by Black-Body Equation • Numerical Calculation is Easiest 100W Black Body Spectral and Integrated Flux Density Rev 2.17 by Chuck DiMarzio, Northeastern University 1992,1993,1995, 1997 .49600 to .50400 micrometers, T = 3000.0 K Maximum Spectral Radiant Exitance = .81762E+06 W/m^2/micron in band Radiant Exitance in Band 6541.5 Watts/m^2 Wide Band Radiant Exitance .45925E+07 Watts/m^2 Fraction of total in band.14244E-02 Spectrum on bbsre.dat **************************************************************************** Photocurrent per Area in Band 2669.5 Amps/m^2 .16663E+23 photons/sec/m^2 Average Responsivity .40808 Amps/Watt .39257E-18 Joules/photon (in band) ... Chuck DiMarzio, Northeastern University

  15. Incident Irradiance • Mostly a Geometric Problem • G describes non-uniformity • Like Antenna Gain Distance =R E = GP/(4pR2) Power =P E = (1?)0.14 W/[4p(0.3)m2] ~ 0.12 W/m2 Comparable to a dark cloud Chuck DiMarzio, Northeastern University

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