Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5

Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
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Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Fundamentals of Light
• Light = Energy
(radiant energy)
– Readily converted to heat
» Light shining on a surface heats the surface
» Heat = energy
• Light = Electro-magnetic phenomena
– Has the characteristics of electromagnetic waves (eg. radio
waves)
– Also behaves like particles (e.g.. photons)
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Lighting Terminology
Light: Radiant energy that excites the retina of the eye.
Lumen: Volume of light
Candlepower: Intensity of light in a specific location.
Illuminance: Light on an object
Lux: metric measurement of illumination
Lumen: measurement of light at its source and the amount
of light output.
Luminaire:The complete light fixture with the light source
and ballast.
Light trespass:Light pollution in unintended areas.
Ballast: A device used with an electric discharge lamp to
obtain the necessary voltage and current to start and
operate the lamp.
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Relationship between frequency and wavelength
λ
λ=
c
ν
Wavelength = speed of light divided by frequency
(miles between bumps = miles per hour / bumps per hour)
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Light emission / absorption governed by quantum effects
Planck - 1900
Einstein - 1905
ΔE = nhν
E p = hν
ΔE
n
h
ν
is light energy flux
is an integer (quantum)
is Planck’s constant
is frequency
One “photon”
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Thermal Nature of the Emission of Radiation
• Black-body radiation
– Matter is made up of inter-related particles which
may be considered to vibrate or change energy
state
– A distribution of energy states exists within a
blackbody
– Matter emits radiation in proportion to the energy
state changes
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Wien’s Displacement Law
λpeak = 2,897,000 / T
where:
T = [ 0K ]
λ = [ nm]
example:
λpeak-sun = 2,897,000/6000 = 475nm
λpeak-plant = 2,897,000/300 = 9700nm
Point: Emission “color = f(T of emitter)
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Planck’s Law
λ
5
1
e
hc
−1
k λT
= f (T , λ )
100
Radiance of 6000 K Object
75
R a d ia n c e (% )
Eλ =
2π c h
2
Radiance of 300 K Object
50
25
0
0
2500
5000
7500
10000
Wavelength (nm)
12500
15000
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Radiance
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Light sources
A light source is something that emits light such as a candle or the sun.
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Light sources
• Visible radiation is a form of energy, part of the electromagnetic
(EM) spectrum that includes radio waves and X-rays, as well as
ultraviolet and infrared radiation.
• Radiation we can see is called light. Light is described by its
wavelength in nanometres (1/1,000,000,000 metre).
Visible spectrum
380-780nm
Blue < 480nm
Green 480-560nm
Yellow 560-590nm
Orange 590-630nm
Red > 630nm
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Color Temperature I
Lamp color can be
specified by several
methods, none of which
is completely satisfactory,
but all of which can be
useful. These include x &
y coordinates on an CIE
chromaticity diagram,
chromaticity measured in
kelvins (K), color
rendering index (CRI)
and spectral power
distribution curves.
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Colour temperature II
•Color temperature refers to the color of a blackbody radiator at a
given absolute temperature, expressed in Kelvins.
•A blackbody radiator changes color as its temperature increases (
first to red, then to orange, yellow, and finally bluish white at the
highest temperature.
A "warm" color light source actually has a
lower color temperature. For example, a coolwhite fluorescent lamp appears bluish in color
with a color temperature of around 4100 K. A
warmer fluorescent lamp appears more yellowish
with a color temperature around 3000 K.
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Light generation devices
Incandescent lamps
-
thermalise electrons excite lattice and ions, radiation emitted
density is so high that spectrum is continuous - mostly IR – Planck limited
Discharge lamps
- light is generated in a plasma (equal numbers of + and -)
- electrons form near Maxwellian distribution
- fast electrons excite atoms & molecules
- atomic lines and molecular bands - Planck limited
LEDs
- drive electrons and holes into p-n junction – motion not random
- e and h recombine and MAY emit light
- carriers not randomised so not Planck limited
Phosphors
- conversion of UV to visible in ionic site in lattice; lattice is heated, ∼50%
loss
- not Planck limited
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Maintenance & Lighting Attributes
S ource
Life (hours)
E fficiency
CR I
C olor
Tem perature
Incandescent
2,000
low est
100
w arm
hot
instant
Accent. Living areas.
H alogen
Infrared (HIR )
3,000
low
100
w arm
hot
instant
Accent. Living areas.
Com pact
Fluorescent
6-10,000
m edium
80
cool to
w arm
w arm
instant
Accent. Living areas.
M etal Halide
10-20,000
m edium to
high
50-80
cool
hot
5-15
m inutes
Accent. All exterior.
High bay.
m edium to
highest
20-80
w arm
hot
15
m inutes
E xterior. P arking
garage.
w arm
instant
w arm
instant
High P ressure
10-20,000+
S odium
T8
15-30,000
very high
70-90
cool to
w arm
T5
15-20,000
very high
70-90
cool to
w arm
Induction
100,000
m edium
85
cool
O perat-ing
Tem perature
Restrike
Applications
hot
instant
All applications
except exterior area
lighting.
Indirect and high bay
lighting.
E xterior. High
m aintenance areas
and areas w ith
restrike issues.
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Incandescent lamps I
Advantages
• Radiant cooling
• Cheap 0.0005$/lumen
• ~ kLm per package
Disadvantages:
• Mostly infrared
• Fragile
• <15-lm/W luminous (<5% power)
efficiency
• Fire hazard, burnt fingers,
maintenance problems
• Lifetime short ~1,000 hrs
resulting in high maintenance
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Incandescent lamps II
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Structure of a HP discharges
All particles at the same temperature - LTE applies
Some lines reach Planck limit and are self-reversed
Few elements are sufficiently volatile
Many metal halides are e.g. Tl, In, Sc, Dy, Al, Sn.
Temperature profile adjusts so that arc centre is hot
enough to provide electrons to carry current
liquid NaI
NaI
Na
Na*
Na+
Hg at high
pressure
Te ~Tg
~ 4 to 7000K
Radiation efficiency
ηrad = Prad/Pin ∼ 40% to 60%
-R
0
R
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
HP Discharge lamp I
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
HP Discharge lamp II
300 400 500 600 700 nm
Perfect lighting quality for TV and natural
colour rendering showing the finest nuances
are provided by the virtually constant
spectrums of POWERSTAR HQI®-TS
lamps in the Daylight (D) light colour – colour
rendering group 1A very good, Ra ≥90.
HQI®-TS in Neutral White DE LUXE (NDL),
colour rendering group 1B (Ra ≥85), meets
the equally high demands in terms of quality
of light.
Even the POWERSTAR HQI®-TS 2000
W/N/L longarc lamps in Neutral White,group
2B (Ra >65), provide good quality light for
demanding visual work.
POWERSTAR HQI®-TS 1000/2000 W/D/S
POWERSTAR HQI®-TS 1000 W/NDL/S
POWERSTAR HQI®-TS 2000 W/N/L
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Low pressure discharge lamp I
Advantages:
• High efficiency 80+
lm/W & High Flux
kLm/lamp
• Moderate cost for large
lamps 0.002$/lm
• Any color temperature
is possible by tri-color
mixing
Disadvantages:
• Lifetime short <10,000
hrs resulting in high
maintenance
• Fragile
• Requires ballast
• Noisy
• Long warm up time
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Low pressure discharge lamp II
Daylight
Mercury
LP discharge lamp
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Low pressure discharge lamp III
LUMILUX® Daylight Colour 860
LUMILUX INTERNA® Colour 827
LUMILUX® Cool White Colour 840
LUMILUX® Warm White Colour 830
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Electrodeless Lamps
In contrast with all other electrical lamps that use electrical connections through
the lamp envelope to transfer power to the lamp, in electrodeless lamps the power
needed to generate light is transferred from the outside of the lamp envelope by
means of (electro)magnetic fields. There are two advantages of eliminating
electrodes. The first is extended bulb life, because the electrodes are usually the
limiting factor in bulb life. The second benefit is the ability to use light-generating
substances that would react with metal electrodes in normal lamps.
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Light Emitting Diode - LED
LED are compact, mechanically stable, need only low voltage operation, can be
dimmed, and have long life time.
For GL higher lumen packages and higher efficiencies must be realized
LED-Emission +
Excitation
White light = Yellow + Blue
Emission from
Phosphors
Yellow emitting
Phosphor
Epoxy
Blue Chip
SMT-Topled ®
400
500
600
Emission Wavelength
700nm
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
CIE Illuminant Types
•
•
•
•
•
•
•
•
•
A Incandescent
C Sunlight
D50 Daylight - Red Shade
D65 Daylight - Neutral
D75 Daylight - Blue Shade
F2 Cool white fluorescent
F7 Broad band white fluorescent
F11 TL84 fluorescent
F12 Ultralume 3000 fluorescent
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Daylight – CIE D
S(λ) = S0(λ) + M1S1(λ) + M2S2(λ)
0,0300−31,4424xD +30,0717 y D
− 1,3515−1,7703xD +5,9114 yD
M2=
M1=
0,0241+0,2562xD −0,7341yD
0,0241+0,2562xD −0,7341yD
4000 K - 7000K
7000 K - 25000K
10 9
10 6
10 3
+0,244063
x D =− 4,6070 3 +2,9678 2 +0,09911
Tc
Tc
Tc
yD = -3,000xD2 + 2,870xD - 0,275
10 9
10 6
10 3
x D =− 2,0064 3 +1,9018 2 +0,24748
+0,237040
Tc
Tc
Tc
yD = -3,000xD2 + 2,870xD - 0,275
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
CIE light sources I
Light
Source
Illuminant
Color
Temperature
Daylight
D65
6500
Kelvin
Average
Daylight
D50
5000
Kelvin
Daylight
Old std.
C
6774
Kelvin
Incande
scent
A
2856
Kelvin
Direct
Sun
B
4874
Kelvin
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
CIE light sources II
80
70
Rel.power
60
50
CIE F2
CIE F7
40
CIE F11
30
20
10
0
350
400
450
500
550
600
650
Wavelength, nm
700
750
800
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Daylight simulators I
GretagMacbeth Sol-Source
Verivide CAC 60-D a CAC_150-5
Datacolor TRU-VUE® 4D
GretagMacbeth
SpectraLight III
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Daylight simulators II
FLR40S D EDL D65/M
450
400
350
Rel power
300
250
FLR40S D EDL D65/M
D65
200
150
100
50
0
350 400 450 500 550 600 650 700 750 800
D65
Wavelength, nm
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Color Rendering Index I
COLOR RENDERING - The chromaticity of a light source defines its "whiteness", its
yellowness or blueness, its warmth or coolness. It does not define how natural or unnatural
colors of objects will look when lighted by the source.
Two colors of lamps can have the same chromaticity, but render colors very differently.
For example, "warm white" fluorescent has about the same chromaticity as high wattage
incandescent, but it has far less deep red in its spectrum. Therefore, red colors will not
appear as bright under WW as under incandescent.
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Color Rendering Index II
In brief, the chromaticity coordinates of the light
reflected by each sample (i = 1 through 8) are
calculated using modified forms of equations 1 through
5 and a resulting color difference, ΔEi, is calculated for
each of the color samples lit by the light source and the
reference illuminant. ΔEi is used to calculate a color
rendering index for each sample, Ri, defined by:
and the CRI (ranging from 0 - 100) is the average of the eight
color rendering indices:
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Color Rendering Index III
Doc. Ing. Michal Vik, Ph.D.: Kolorimetrie – KME5
Color Rendering Index IV