1. May 02002 Chuck DiMarzio, Northeastern University 10100-6-1 ECE-1466 Modern Optics Course Notes Part 6 Prof. Charles A. DiMarzio Northeastern University Spring 2002

2. May 02002 Chuck DiMarzio, Northeastern University 10100-6-2 Lecture Overview Some Radiometry –Terminology –Equations Relating Radiometric Parameters –Photometric Parameters Some Numbers A Little Bit of Scattering Theory Some Applications in Microscopy

3. May 02002 Chuck DiMarzio, Northeastern University 10100-6-3 Radiometric Quantities

4. May 02002 Chuck DiMarzio, Northeastern University 10100-6-4 Radiometry and Photometry , Flux M, Flux/Proj. Area I, Flux/  L,Flux/A  E, Flux/Area Rcd. Radiant Flux Watts Luminous Flux Lumens Radiant Exitance Watts/m 2 Luminous Exitance Lumens/m 2 =Lux Radiance Watts/m 2 /sr Luminance Lumens/m 2 /sr 1 Lambert= (1L/cm 2 /sr)/  1 ftLambert= (1L/ft 2 /sr)/  1mLambert= (1L/m 2 /sr)/  Radiant Intensity Watts/sr Luminous Intensity Lumens/sr 1 Candela=1cd=1L/sr Irradiance Watts/m 2 Illuminance Lumens/m 2 =Lux 1 Ft Candle=1L/ft 2 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.

5. May 02002 Chuck DiMarzio, Northeastern University 10100-6-5 Luminance and Radiance 400500600700800 0 1 1.8 Wavelength, nm Photopic Sensitivity y This curve shows the relative sensitivity of the eye. To convert to photometric units from radiometric, multiply by 683 Lumens Per Watt

6. May 02002 Chuck DiMarzio, Northeastern University 10100-6-6 Radiance in Images dA’ d1d1 d2d2 dA 1 dA 2 z

7. May 02002 Chuck DiMarzio, Northeastern University 10100-6-7 Typical Radiance Levels Our Example = 0.0037/  W/m 2 /sr ~ 0.001 W/m 2 /sr at f/1 Half-Lux Camera = 0.0044 W/m 2 /sr

8. May 02002 Chuck DiMarzio, Northeastern University 10100-6-8 Black-Body Equation (1)

9. May 02002 Chuck DiMarzio, Northeastern University 10100-6-9 Black Body Equations (2) T=300k 500 1000 2000 5000 10000

10. May 02002 Chuck DiMarzio, Northeastern University 10100-6-10 Solar Irradiance on Earth 0200400600800100012001400160018002000 0 500 1000 1500 2000 2500 3000 Data from The Science of Color, Crowell, 1953, Wavelength, nm E, Spectral Irradiance, W/m 2 /  m Exoatmospheric filename=m1695.m Sea Level 5000 K Black Body Normalized to 1000 W/m 2 6000 K Black Body Normalized to 1560 W/m 2

11. May 02002 Chuck DiMarzio, Northeastern University 10100-6-11 Tungsten Lamps: Hot is Good! 3000 K –20 Lumens per Watt – peak =1.22  m –x =.4357y =.4032 z =.1610 3400 K note: (3400/3000) 4 =1.64) –34 Lumens per Watt note: 20X1.64=33 – peak =1.09  m –x =.4112y =.3935 z =.1953 x y

12. May 02002 Chuck DiMarzio, Northeastern University 10100-6-12 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

13. Lighting Efficiency 100 1000 10000 100000 1000000 1101001000 10000 Power Input, Watts Light Output, Lumens Fluorescent Hi Pressure Na Metal Halide Lo Pressure Na Incandescent 94 Lumens/Watt at 7000K (Highest Efficiency Black Body) 20.7 Lumens/Watt at 3000K Thanks to John Hilliar (NU MS ECE 1999) for finding lighting data from Joseph F. Hetherington at www.hetherington. com. 10 June 1998

14. May 02002 Chuck DiMarzio, Northeastern University 10100-6-14 Source Intensity Fraction of Light in Filter Passband –Given by Black-Body Equation –Numerical Calculation is Easiest 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)... 100W 0.142 W

15. May 02002 Chuck DiMarzio, Northeastern University 10100-6-15 Incident Irradiance Mostly a Geometric Problem G describes non- uniformity –Like Antenna Gain Distance =R Power =P E = GP/(4  R 2 ) E = (1?)0.14 W/[4  0.3)m 2 ] ~ 0.12 W/m 2 Comparable to a dark cloud