--~-~~~~~~~~~~~~~--

DISPLAY REFLECTION CHARACTERIZATION

George R. JonesNIST

Gaithersburg, MD 20899

jones@eeel.nist.gov

FLAT PANEL DISPLAY LABORATORYG* R.. JONES 301-975-4225

REFLECTION

REFLECTIONS FROM DISPLAY SURFACEREFLECTED LUMINANCE FROM A DISPLAY SURFACE ISUSUALLY CHARACTERIZED AS BEING DIFFUSE(LAMBERTIAN) AND SPECULAR. IS THIS ACCURATE?

LENS FOCUS AND APERTURE PROBLEMSDOES THE FOCUS LENGTH AND APERTURE OF THEMEASURING LENS HAVE AN EFFECT ON THE MEASUREDREFLECTED LUMINANCE?

FLAT PANEL DISPLAY LABORATORYG.. R~ ..JONES 301-975-4225

..........---------BRDFGENERALIZATION OF

"L = qE"

dLrz

dLr(er'~r) =B(ei'~i'er'~r)dEi(ei'~i)

FLAT PANEL DISPLAY LABORATORYG.. R.. JONES 301-975-4225

TOTAL REFLECTED LUMINANCE21t 1t / 2

Lr(en~r) = f fB(ei'~i,en~r)dEi(ei,~Jo 0

dE. =L.fe. ~. ) cose .dOI 1\ ,,0/, I

INCIDENT LUMINANCE

ELEMENT OF SOLID ANGLE

dO = sin e .de .d~ ·I I 0/ I

dLr(8r'~r) =

B (8 i , ~ i ,8 r , ~ r ) dE i (8 i , ~ i )

f'-I FLAT PANEL DISPLAY LABORATORYG.. R.. JONES 301-975-4225

--.-.......

~ ~~---.---....--

THREE-COMPONENT MODEL OF REFLECTANCE

B=D+S+HLAMBERTIAN D /(DIFFUSE) = q = Pd 1t

SPECULAR S = 2ps8{sin2er - Sin2ei)8{~r -~i +1t)

HAZE H = H{ei'~i,er'~r)

Lr(er'~r) = qE + psLs(er'~r +n)21t 1t / 2

+ f fH(8i'~i,er'~r)Li(ei,<I>i)cos(ei)dQo 0 .

FLAT PANEL DISPLAY LABORATORYG. R.. JONES 301-975-4225

--

I

,

I

o(1)1""+

(1)('")1""+o...,

-

CDenII

Wo

en::ro~::J

,, ,\ --- --- ,, "\~ ,

CD\ --~CD' ,-. \ I -., ,V \ ~ CD / A' ~ ,0\ II II ,/0,

I '\ + ", ~,\ ~,\ CD en "\ en :\ ,, ,, ,\ ,\ ,, ,, ,\ ,\ ,, I, ,\ ,\ ,, ,, I\ I\ ,, ,, ,, ,\ ,, ,, I\ ,, ,\ '\ '\ '\ '\ "

i

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-- -. -

- ---

.-- ~ !88 ~ ~ ~ ... .. .. .. ... ~ .. _

FLAT PANEL L"')ISPLAV LABORATORYG.. Roo JONES 301-975-4225

POPULAR LAPTOP COMPUTER AMLCD FPD

10 I 12...-.... 10w

1 !r\ :

--........

'-"c:0

I \;10CO

:J -5 0 5 10C>tt= 0.1c:0

()0Cf)

0.01J2LL [ ...0c:::m 1E-3

-80 -60 -40 -20 0 20 40 60 80

Source Angle (degrees)

"..........

.!!!~"'-'

co.-.....ca...~C)

Ii:Cooot')...~LLC~m

POPULAR LAPTOP COMPUTER AMLCD FPD

121110987654321o

-90 -70 -50 -30 -10 10 30 50

Source Angle (degrees)

70 90

FLAT PANEL DISPLAY LABORATORYG* R.. JONES 301-975-4225

I \ ... .. _ _ _ _ _ _ _ _ .. .. .. J!8.. _ _ . .

....................

IntegratingSphere

FPD

Lamp Lamp

Detector

FLAT PANEL DISPLAY LABORATORYG* R.. JONES 301-975-4225

r

FLAT PANEL DISPLAY LABORATORYG.. I~.. JONES 301 -975-4225

-- -- -- -- -- - - - - --- '~

Case Measured Calculated ErrorCase 1

Int. Sph.+ 49.8 46.6 -6.3%Hole

Case 2 75.3 77.7 3.2%Int. Soh.Case 3Lamps 0.153 0.148 -3.2%

e = :1:250e = :1:300 0.0890 0.0861 -3.3%

e = :i:35° 0.0535 0.0527 -1.4%

. . . . . . . . . l8. . 18. . . . . .

FLAT PANEL DISPLAY LABORATORYG* R.. JONES 301-975-4225

11L..

10L I ""Y...Jr I 20 FOV'-""

9Lc: 1.11 I.I 10 FOV0 8:+:imL.. 7:]C)

6q::c:0 5(.)

0

4('f)L..

J2 3LL

2£:)c:::

1r- Im IIjyI I

-4 -2 0 2 4

SourceAngle(degrees)

Diffuse Component0.01

-80 -60 -40 -20 0 20 40 60 80

Light SourceAngle (degrees)

FLAT PANEL DISPLAY LABORATORYG* R.. JONES 301-975-4225

- - '- ... ~ -- ~ .. .. .!8 .. _ . .

SPECIALLY PREPARED SAMPLE (D + S + H)

100 ::-if 100

,t......... Specular

SpecularPeak

Component I I 10 HazeI -

10 .. I -1

t I II

en.........

1 l I I 1 -.':10 -5 0 5'-" HazeLLC

t ComponentI I \ RESOLUTIONm < 0.10

I I r "0.1

~ ~ - ~ ~ - - - . . . . . . . . . ..UNFOLDED SPECULAR CONFIGURATION

Focus on Screen or Source

Screen

Image of Detector

Single Ray from Source

HazeReflection

/'

;'

This figure keeps theLens lens in the same place

for illustration purposes.

DetectorDistance the lens and thedetector depends uponthe object distance.

For longer focal positionsmore light comes fromnear the haze peak thanfor closer focal positions.

FLAT PANEL DISPLAY LABORATORYG.. R.. JONES 301-975-4225

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co

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ooceno mz X

--ien mo zc 0;0 mo 0m r

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All measurements were madeusing a 31 x 31 pixel squarecenter on the peak CCDreading (961 pixels)

The 2.3 m focus correspondsto focussing on the source.

The 1.3 m focus correspondsto focusing on the screen

FI_AT PANEL DISPLAY LABORATORYG~ Ft~ .~J~:>~\§ES 30~1-97"5 4225

1\ :... ~ - -...._

LuminanceTest Light (CCD Reduction

Sample Source Aperture Focus / Counts) (%)

Haze Extended 132 2.3 m 5.42E+07Extended 132 1.3 m 4.34E+07

-20.0

Haze Extended 12.8 2.3 m 5.16E+07Extended 12.9 1.3 m 4.34E+07

-16.0

A Extended 132 2.3 m 5.75E+07Extended 132 1.3 m 4.77E+07

-17.0

A Extended 12.8 2.3m 5.32E+07Extended 12.9 1.3 m 4.05E+07

-23.8

Haze Point 132 2.3m 6.78E+06Point 132 1.3 m 6.19E+06

-8.7

Haze Point 12.8 2.3m 1.52E+07Point 12.9 1.3 m 5.53E+06

-63.6

A Point 132 2.3m 2.50E+06Point f32 1.3 m 2.39E+06

-4.6

A Point f2.8 2.3m 2.07E+07Point 12.9 1.3 m 5.35E+06

-74.2