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### ECE-1466Modern OpticsCourse NotesPart 6

Prof. Charles A. DiMarzio

Northeastern University

Spring 2002

Chuck DiMarzio, Northeastern University

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

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 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

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

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

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

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

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

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

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

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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