Transcript light - PowerWiki

Power Engineering 3
1. Radiation, Visible Radiation, Light, Physiology of Vision, Physics of Light,
Photometric Values
2. Lighting Measurements (illuminance, luminance, luminous flux, luminous
intensity)
3. Light Sources
4. Luminaires
5. The Principles of Interior Lighting
6. Lighting Systems
7. Lighting system calculations methods
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Visible Radiation
and
Light
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transfer of energy through a space in
the form of electromagnetic waves or
particles
Radiation
Natural source of electromagnetic radiation is Sun
The Light Technique does not examine
essence either force effects or continuousness of radiation
but watching the distribution of the energy flows
in the smooth transitions between the considered sites.
Decisive is the energy transmitted by radiation for 1 s = power transmitted by radiation =
= radiant flux
Fe = dWe / dt
(W )
Any radiation can be decomposed into components with sinusoidal course.
Every component is characterized by
certain
frequency
Wavelength l
n
(Hz) [ monofrequency radiation] or
is usually expressed in nm =
10-6 m
or in
wavelength l
mm = 10-9 m
l depends on the speed of radiation propagation;
► in vacuum l
= c0 · n -1
(m; m·s-1, Hz) ;
speed of the electromagnetic wave propagation in vacuum
c0 = 2,998 108 m·s-1
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RADIATION SPECTRUM
Components of radiation sorted by
frequency or wavelength
Visible radiation (VIS)
[ 380 – 770 nm ]
radiation capable of eliciting
visual sensation (perception)
ultraviolet
UV
Optical
radiation
VIS
visible
IR
infrared
The electromagnetic spectrum
indicatively sorted by frequencies and wavelengths
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Light in the Course of History
Physical view:
• Some Greek philosophers [Ptolemaios (70 – 147 B.C.)] thought that the rays of
light come from eye.
• Among the opponents of this idea was for example Demokritos (460 - 432 B.C.)
He said that the vision is conditional on slight indestructible bodies, which are
coming out of the observed objects and hit the surface of the eye.
Until the turn of 17th and 18th century appear competing theory about the nature of light:
• Isaac Newton (1643 – 1727; English physicist) viewed light as a stream of
point particles of different sizes emanating from glowing objects and hitting
the eye. This results in a sensation of light.
„corpuscular theory“
When the impact at the interface with a denser medium
smaller particles are deflecting more, bigger less.
• Cristiaan Huygens (1629 – 1695; Dutch mathematician and scientist)
Considered light as a longitude waves of special environment filling the entire
space.
„wave theory“
This enabled explain interference of rays and bending of light.
The wave theory was verified even by the French physicist
Étienne-Louis Malus (1775 -1812) who converted it into a analytical form (1808).
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Light in the Course of History
Break of the looking at light 1873
James Clerc Maxwell (1831-1879); Scottish physicist
• unified theory of electrical a magnetic effects
• presented a general mathematical description of the electromagnetic field
[Maxwell´s equations]
• author of the theory of electromagnetic origin of light
• speed of propagation of an elmag field is approx. that of the speed of light
• in vacuum electromagnetic waves are always transvers
• light is elmag waves of the certain wavelengths perceived by human vision
Maxwell´s theory accurately reproduced the available experimental data.
At the atomic level it had to be clarified by quantum electrodynamics.
Albert Einstein (1879 – 1955) German-born theoretical physicist
•showed that the light has together properties wavelength as well as corpuscular
dual character of light
•Introduced the concept of the photon; discovered regularities of the photoelectric
effect;
•Put the foundations of quantum theory of light
•Is the author of theory of relativity
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Light
Visible radiation evaluated by the vision of observer according
to the spectral sensitivity of the eye to radiation of different wavelengths
relative spectral sensitivity of the eye s(l)
for the normal photometric observer
1,0
0,9
s(l)
0,8
0,7
0,6
0,5
Night
vision
Day vision
0,4
0,3
0,2
0,1
0
400
500
600
700
wavelength (nm)
Wavelength region of the visible light
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Light radiation
= Visible radiation evaluated by the vision of
observer according to the spectral sensitivity of the
eye to radiation of different wavelengths
In the visible region of the spectrum gives each
monofrequency radiation completely certain color
sensation  monochromatic radiation
Illustrative distribution of tones in the spectral range of visible radiation.
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Visible radiation
Light – factor of making the environment
visual perception
„light“ influence
overal wellbeing
By vision man gets 80 to 90% of all information
By consuming for that up to 25% of energy intake
Goal : by good lighting create visual comfort of observer
Visual comfort
 vision works optimally – good vision and differentiation
 man feels mentally well, environment has a pleasant impact
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Lighting
Appropriate
Inappropriate
• Higher productivity
• Growing also production
quality
• Higher safety
• Fatigue grows more
slowly
• Easier recovery
• Increase the number of
failures
• Decrease the production
quality
• Rise in the number of
accidents
• Higher eye fatigue
• Increasing overall fatigue
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Influence and Impact of
Optical Radiation
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Influence and impact of optical radiation
Light - means to transfer and obtain visual information about the surrounding environment
Good lighting is meant for
visual performance
task difficulty
visual comfort
pleasant environment
subjective feelings
psychological aspects
personal safety
accidents, feel safe
Light is important factor of creation of environment
Inappropriate lighting
eye fatigue
Burning eyes, headache
overal organism fatigue
Common causes
of errors
glare
Body/organism
overload alarm
Injuries, accidents
incorrect color corelated temperature
of light sources
inconsistency with the
illumination level
wrong color resolution
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Light controls our biological processes
Many of the processes taking place in about 24 h (ie. circadian) cycles
Depending on the rotation of the Earth around the Sun
active phase during the day – resting phase during the night
For example: body temperature, blood pressure, pulse rate, metabolism,
immune function, sexual function, physical and mental activity
Light govern our inner clock – sensor: third type of photoreceptor „C“
Relative spectral sensitivity
„C“ – circadian sensor
V – Eye for the day vision
(prevail cones)
V´ – Eye for the night vision
(prevail rods)
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The basic circadian cycle – periodic alternation of light and darkness
Central biological clock also controls the peripheral clocks of individual organs,
especially the lungs, kidneys, heart and pancreas, etc.
⇒
Therefore, changes in the activity of human organism and
accompanying changes in temperature, blood pressure, heart rate, etc.
A typical daily rhythm of changes in the levels hormones melatonin and cortisol along
with corresponding changes in body temperature and degree of human activity.
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The consequences of disruption of biorhythms
- discomfort
- sleep disorders
- serious illness
Examples of causes
• rapid shifts between time zones (jet lag)
• work in alternate or night shifts
• long-term stay in an environment with very low levels of illuminance
Some resident especially of big cities, mainly during the winter
time can suffer from
seasonal affective disorder - SAD
(e.g. Approx. 10% New York citizens)
Consequences : - reduction of working, social and sexual activity
- feelings of sleepiness during the day
- changes in behavior of individuals in groups
- weight gain
- processes reminiscent of the events during the animals winter sleep
- for evolving organisms up to suppression of some organs development
Improvement : - repetitive illumination by levels
2 500 lx
10 000 lx
2 h/day
0,5 h/day
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„Body Blues“ illness
Expressions :
- vegetative depressive symptoms
- difficulty in concentrating
- feeling a lack of energy
- feeling of anxiety up to depression
- sexual aversion
- sleep disorders (sleepiness during the day)
- irritation
- increased sensitivity to criticism
Major cause:
low level of the tissue hormone serotonin (hormone of „happiness“)
[participates in brain processes related to the occurrence of a mood]
Relief:
carbohydrates
after 1 h sharply drop of mood
patients overeat sweets and gain weight
Illness 3x more often at women – much slower reproduction of serotonin than men
Expert estimate: in the world disease affects approximately 1 million women
Therapy: minerals, vitamins B1, B2, B6, D, selenium, folic acid
Staying in a pleasant environment with a higher level of illuminance
► Often compensation of the lack of light by suitable intense lighting even for a
rearing of farm animals (e.g. stables) to ensure normal growth for evolving
organisms of young ones.
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Research of the response of the brain centers
to external light stimuli received by sight
By exposing to light of certain color and suitable frequency of its flickering
it is possible to stimulate certain brain centers
Use : prevention and treatment of certain diseases especially of psychological nature
Constructed devices, elaborated procedures and instructions
– patient observes (cca 20 min) defined field of view,
where for the selected period (3, 5, 10 min)
in the certain rhythm ( f = 8, 10, 12 Hz)
the light of certain luminance and color is flickering
– for the one procedure it is applied e.g. 3 alternatives
– each procedure is pre-programmed by the doctor´s prescription
Research is still continue in the framework of the CIE
„The Effects of Dynamic and Stereo Visual Images on Human Health “
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Another possible use of visible radiation
– treatment of infant hepatitis by irradiation of infants with blue
light of metal halide lamps
– photosynthesis
[provides the basic cycle of substances on Earth, life would not exist without it.
Exposure to visible radiation occurs in the green parts of plants for the presence of
chlorophyll (leaf green) as a catalyst a chemical process (photosynthesis), wherein
carbon dioxide and water are formed into organic compounds].
– optics
– photography
– electrical engineering
– chemistry
And other fields.
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UV-A 315 - 400 nm
Ultraviolet radiation (UV)
UV sources: Sun, artificial light sources (especially Hg discharge lamps)
UV rays pass well through water, quartz,
some glass (e.g. potassium phosphate),
organic glass and air
UV rays will not pass through even a thin layer of metal
ordinary glass (esp. leaded),
[discharge lamps bulbs for general lighting pass only min UV]
Some materials (fabrics, prints, paintings, etc.) after
irradiation with higher doses of UV aging faster, lose color, or
may undermine their structure and mechanical strength.
UV-B 280 - 315 nm
UV-C 100 - 280 nm
If there is no significant breakdown of the
ozone layer, then a high layer of air in the
atmosphere practically absorb UV radiation
from the Sun.
In our climate zone the UV radiation reach
the Earth´s surface only on a sunny day at
the high mountains.
Pigmentary effects (protective browning) – 297 nm, 340 nm.
At higher doses vessel expansion, short-term inflammatory reddening of the skin (erythema).
Erythemal effects esp. dangerous to mucous membranes.
Intense UV irradiation of the skin can cause serious disease, even cancer.
UV radiation excites phosphor luminescence – use at the fluorescent lamps to fluorescent analysis etc.
UV around 283 nm supports the production of vitamin D - accelerates the deposition of calcium in the bones;
Treating a number of diseases (rickets, sinusitis, metabolic disorders, TB, skin, etc.)
Source: high pressure Hg discharge lamps – „mountain sun“.
Germicidal effects (265, 254 nm) – destruction of bacterial viruses etc., sterilization of air, liquids and
solids. Special germicidal lamps. Wide use in medicine, industry and agriculture (e.g. against molds).
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Infrared radiation (IR)
IR-A 780 - 1400 nm
IR – carrier of radiant heat
Use: heating, warming, drying
IR sources: Sun, warm housing, infrabulbs, others
IR easily pass through
very little pass through
IR-C 3000 - 106 nm
air, fog
thin layers of metal etc.
glass (esp. containing oxides Fe)
water, thermal insulators
IR-A
penetrates the skin, dilates blood
vessels, improves blood flow,
accelerates healing, soothes pain
Another use of IR:
IR-B 1400 - 3000 nm
- use for treating of various diseases
(including rheumatic problems)
- diathermy
- infraphotography
- thermal imager (observation at night – converting to the visible light)
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Thank you for your attention
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