Physical processes employed in artificial lighting sources include incandescence, luminescence, fluorescence, and phosphorescence. Incandescence uses heat to produce light from materials like tungsten filaments. Luminescence produces light through chemical or electrical excitation of gases and vapors. Fluorescence absorbs light at one wavelength and re-emits it at another, making UV light visible. Phosphorescence stores light energy and releases it later as glow. Efficient lighting combines luminescence and fluorescence.
The human color vision describes about The Cornea, The Sclera/ Sclerotic coat, The Pupil, The Retina, The Choroid Coat, The vitreous humor, The aqueous humor, The lens, Foveal Pit, Yellow Spot, Blind Spot, How the Human Eye Works, The Rods, The Cone Cells, Types of Cones, Spectral sensitivity, Defective color vision/ Color blindness, Symptoms of Color Blindness, Causes of Color Blindness, Trichromates, Dichromates, Monochromates, Anomalous Trichromates.
The human color vision describes about The Cornea, The Sclera/ Sclerotic coat, The Pupil, The Retina, The Choroid Coat, The vitreous humor, The aqueous humor, The lens, Foveal Pit, Yellow Spot, Blind Spot, How the Human Eye Works, The Rods, The Cone Cells, Types of Cones, Spectral sensitivity, Defective color vision/ Color blindness, Symptoms of Color Blindness, Causes of Color Blindness, Trichromates, Dichromates, Monochromates, Anomalous Trichromates.
Shedding Light on Lumens - Capturing the True Efficiency Of White LightCindy Foster-Warthen
Craig Bernecker and Naomi Miller, presenters: Lumens and foot-candles are measures of light so often considered critical to lighting design and the energy efficiency of lighting systems, yet the basis for these units is also often misunderstood. This seminar reviews the foundation for the lumen (and in turn, foot-candles), illustrates why the lumen often misrepresents the perceived quantity of light, and why the lumen is inadequate to describe nighttime visibility, circadian effect, lighting for plant growth, and more. Should we use different measures to evaluate the energy efficiency of lighting systems, especially LEDs?
In this presentation on Radiometry and Photometry we will look at Radiometry, the detection and measurement of radiation across the full electromagnetic spectrum, including ultraviolet, visible and infrared radiation. Photometry is concerned only with the visible portion of the spectrum, from about 380 to 780 nanometers.
Shedding Light on Lumens - Capturing the True Efficiency Of White LightCindy Foster-Warthen
Craig Bernecker and Naomi Miller, presenters: Lumens and foot-candles are measures of light so often considered critical to lighting design and the energy efficiency of lighting systems, yet the basis for these units is also often misunderstood. This seminar reviews the foundation for the lumen (and in turn, foot-candles), illustrates why the lumen often misrepresents the perceived quantity of light, and why the lumen is inadequate to describe nighttime visibility, circadian effect, lighting for plant growth, and more. Should we use different measures to evaluate the energy efficiency of lighting systems, especially LEDs?
In this presentation on Radiometry and Photometry we will look at Radiometry, the detection and measurement of radiation across the full electromagnetic spectrum, including ultraviolet, visible and infrared radiation. Photometry is concerned only with the visible portion of the spectrum, from about 380 to 780 nanometers.
Trades of Strip Lite Consumer Luminaires, Slim Lite Consumer Luminaires, Prim Rose Consumer Luminaires, Melody Box Consumer Luminaries, Corrosion Dust And Jet Proof Luminaires (IP 65)
, Corrosion Proof Luminaires (ip 65), Jet Proof Luminaires (IP 65), Corrosion Dust Proof Luminaires (IP 65), superior grade quality Lighting Luminaries. These are widely appreciated in the industry for their reliability and optimum performance.
REFLECTORS INFLUENCE TO LUMINARY EFFICIENCYTomas Pukas
This presentation describes how big is influence of reflector to the efficiency of luminaries even if these luminaries are of the same power and are equipped with the same type of lamps and used in identical applications.
For more information please contact:
ELEKTROS TAUPYMO SPRENDIMAI, UAB
P. Luksio str. 1, Vilnius 08221, Lithuania
E: info@ecolight.lt T: +370 5 2328207 F: +370 5 2784262 W: www.ecolight.lt
The presentation is the continued part of Color Theory section. In this part you can learn about the history of the color, how color theory established & evaluation of color theory, Physiological Principles of color, or Emotional Response of Colors.
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
NVBDCP.pptx Nation vector borne disease control program
Notes2
1.
2. Physical Processes Employed in the
artificial sources
• 1. Incandescence - Thermo luminescence is by definition radiation
at high temperature. The sources employing this process are
Incandescent Lamp, Gas Lamp, (flames and in oil Lamps and wax
candles). They lead to a continuous spectrum of radiation.
• 2. Luminescence -Luminescence Electro luminescence by
definition Chemical or Electrical Action on gases or vapour
radiation. Here colour of radiation depends on the material
employed. Usually this process leads to Line or Band Spectrum.
• 3. Fluorescence - Fluorescence is a process in which radiation is
absorbed at one wavelength and radiated at another wavelength
e.g.UV impinging on Uranium – Fluorescent oils. This re radiation
makes the light radiated visible.
3. • 4. Phosphorescence - Phosphorescence is a process when energy is
absorbed at some time and radiated later as glow. Examples of this
process are Luminous paints that contain calcium sulphide that lead to
Phosphorescence. They produce light Radiation after exposure to
light.
In practice good efficient lighting is obtained by combining
Luminescence and Fluorescence. Fluorescent lamp is Luminescent
source of low luminous value activating Fluorescent surfaces which
lead to visible radiation. Here intensity depends on gas or vapour
involved and phosphor material. However, the temperature of the
material play a role in radiation.
4. Visible light is light that the human eye can perceive. When you look
at the sun's visible light, it appears to be colourless, which we call
white. Although we can see this light, white isn't considered part of
the visible spectrum. That's because white light isn't the light of a
single colour but instead many colours.
5.
6. Visual tasks
• The visual system carries out a number of complex
tasks, including the reception of light and the formation of
monocular representations.
• The build up of a binocular perception from a pair of two
dimensional projections.
• The identification and categorization of visual objects.
• Assessing distances to and between objects and guiding body
movements in relation to visual objects.
• The psychological process of visual information is known
as visual perception, a lack of which is called blindness.
• Non-image forming visual functions, independent of visual
perception, include the pupillary light reflex(PLR) and
circadian photoentrainment.
7. • Eye acquires > 80% information acquired by human.
• An Eye comprises of Iris, Focusing Lens and Retina. It
Resembles – a Camera in general structure and action.
Eye Camera
Iris
Lens
Retina
Shutter
Lens
Film
8.
9. Ciliary Body
A structure located behind the iris (rarely visible) which produces
aqueous fluid that fills the front part of the eye and thus maintains
the eye pressure. It also allows focusing of the lens.
Conjunctiva
A thin lining over the sclera, or white part of the eye. This also
lines the inside of the eyelids. Cell in the conjunctiva produce
mucous, which helps to lubricate the eye.
Cornea
The transparent, outer "window" and primary focusing element of
the eye. The outer layer of the cornea is known as epithelium. Its
main job is to protect the eye. The epithelium is made up of
transparent cells that have the ability to regenerate quickly. The
inner layer of the cornea is also made up of transparent tissue,
which allows light to pass.
10. Iris
Inside the anterior chamber is the iris. This is the part of the eye
which is responsible for one‘s eye colour. It acts like the diaphragm
of a camera, dilating and constricting the pupil to allow more or less
light into the eye.
Pupil
The dark opening in the centre of the colored iris that controls how
much light enters the eye. The colored iris functions like the iris of
a camera, opening and closing, to control the amount of light
entering through the pupil.
Lens
The part of the eye immediately behind the iris that performs
delicate focusing of light rays upon the retina. In persons under
40, the lens is soft and pliable, allowing for fine focusing from a
wide variety of distances. For individuals over 40, the lens begins
to become less pliable, making focusing upon objects near to the
eye more difficult. This is known as presbyopia.
11. Retina
The membrane lining the back of the eye that contains
photoreceptor cells. These photoreceptor nerve cells react to
the presence and intensity of light by sending an impulse to the
brain via the optic nerve. In the brain, the multitude of nerve
impulses received from the photoreceptor cells in the retina are
assimilated into an image.
Optic Nerve
The optic nerve is the structure which takes the information
from the retina as electrical signals and delivers it to the brain
where this information is interpreted as a visual image. The
optic nerve consists of a bundle of about one million nerve
fibers.
14. Colour theory
• Newton thought that colours were a sensory experience,
rather than a property of light.
• Newton’s theory of colour was that the sun’s light, or any
other white light, was a mixture of rays of light, each with its
own refrangibility, by which he meant characteristic angle of
refraction in a prism.
• What is a colour: when we look at a scene, our visual nerves
register colour in terms of the attributes of colour the
amount of green-or-red; the amount of blue-or-yellow; and
the brightness.
15. Colour nerves sense green or red — but never both; and
Blue or yellow — but never both.
Thus, we never see bluish-yellows or reddish-greens. The
opposition of these colours forms the basis of colour vision.
Ewald Hering (1834-1918) devised the first accurate
theory of colour vision.
16. A modern representation of colour space. This is
conceptually similar to Hering’s circles, but the middle
fades to gray.
17. • Modern colour theory is based on three primary
colours red, green and blue.
• Also warm and cool colours has been important since at
least the late 18th century used in design practices today
• Colour theory has described perceptual and psychological
effects as
Warm colours are said to advance or appear more
active in a painting, warm colours are said to arouse or
stimulate the viewer.
while cool colours tend to recede used in interior
design or fashion, also cool colours calm and relax.
18. Additive colour
• Additive colour synthesis is the creation of colour by
mixing colours of light. Human vision relies on light
sensitive cells in the retina of the eye. There are two
basic kinds of sensors. These are rods and cones.
• Rods are cells which can work at very low intensity, but
cannot resolve sharp images or colour.
• Cones are cells that can resolve sharp images and
colour, but require much higher light levels to work.
• The combined information from these sensors is sent to
the brain and enables us to see.
19. • There are three types of cone. Red cones are sensitive to
red light, green cones are sensitive to green light, and blue
cones are sensitive to blue light. The perception of colour
depends on an imbalance between the stimulation level of
the different cell types.
• Additive colour processes, by having the capability to
generate an image composed of red, green, and blue light.
• Since the intensity information for each of the three
colours is preserved, the image colour is preserved as well.
• The spectral distribution of the image will probably be
wrong, but if the degree of intensity for each of the
primary colours is correct, the image will appear to be in
right colour.
20. The three primaries in light are red, blue, and green, because
they correspond to the red, green, and blue cones in the eye.
21. Red + Green = Yellow
Red + Blue = Magenta
Green + Blue = Cyan
Computer monitors and televisions are the most common
examples of additive colour.
22. Subtractive colour
• When learning basic colour theory, art students typically use
familiar colours like red, yellow, and blue.
• The most frequently used primary colours for subtractive
colour mixing are cyan, magenta and yellow.
• Subtractive colour mixing is employed with paints and
pigments, in contrast with additive colour mixing with
coloured lights for spotlighting and theatrical lighting.
• Subtractive colour processes work by blocking out parts of
the spectrum. The idea of subtractive colour is to reduce the
amount of undesired colour reaching the eye.
23. • The three primaries on the artist’s colour wheel
are red, blue, and yellow.
• Yellow light is observed when all blue light is removed from
white light, magenta forms when green is removed, and
cyan is produced when red is removed.
• If, for example, you had a yellow image, you would want to
have a dye that would let red and green reach the eye, and
block out blue. The additive secondaries become
subtractive primaries, because each of the additive
secondaries will reflect two of the additive primaries, and
absorb one of the additive primaries.
• White cannot be produced by any combination of the
primary subtractive colours, which is the main reason that
no mixture of coloured paints or inks can be used to print
white.
24. When all three primary subtractive colors are
added, the three primary additive colors are
removed from white light, leaving black (the
absence of any color).
26. Innovation in lighting has brought new products and
classifications to the home, office and industrial.
Lighting classifications include indoor and outdoor lights
with entirely different purposes.
Street and highway lighting can be low-pressure sodium
that has poor colour rendition and that takes 10 minutes to
illuminate. Stadium lights, Emergency lighting,
Photographic lighting etc.,
27. Natural: Sunlight, candlelight and firelight; this is light
that moves and is sometimes referred to as kinetic.
Artificial:
Incandescent
Fluorescent
LED
High Intensity Discharge
Outdoor Solar
Broad classification of light
28.
29. • An incandescent bulb uses heat caused by an electrical
current.
• When electrical current passes through a wire, it causes the
wire to heat. The wire, or filament, gets so hot that it glows
and gives off light.
• Everyday incandescent light bulbs have a filament made of
tungsten. Since the hot tungsten would quickly burn away
if it were exposed to oxygen, it must be placed in a sealed
glass bulb which is either evacuated or filled with a gas that
wont let it burn.
• Because of their inefficiency, incandescent light bulbs are
gradually being replaced in many applications by other
types of electric lights, such as fluorescent lamps, compact
fluorescent lamps (CFL) etc.,
30.
31. • Fluorescent lamp produces white light.
• The average life is 7500 hours.
• The light output is 70 lumens per watt.
• They have poor rendering especially for red colour.
32.
33. • Light-emitting diodes (LED) are semiconductors. As electrons
pass through this type of semiconductor, it turns into light.
• Compared to incandescent and CFL bulbs, LED lights are more
efficient at turning energy into light.
• Therefore, less of the energy radiates from the bulb as heat.
This is why LED bulbs are cooler during operation than
incandescent and CFL bulbs.
• As the light-emitting diodes create light, they warm up quite a
bit for their size. LEDs are heat sensitive, so it's important that
the heat move away so that it doesn't damage the
semiconductors.
• In order to do this, these lights need a system to keep cool.
Most LED lights have a heat sink plate that moves the heat
away from the light-emitting diodes through the heat sink
plate.
34. Classification of light in Decoration
• Ambient: A hidden source of light that washes a room
with a glow. It flattens an interior and creates very little
shadow.
• Accent: Directional lighting or lighting that adds interest
or highlights a certain object or unusual architectural
feature in a room.
• Task: Task lighting is just that; lighting that's used to
perform daily activities such as
reading, cooking, shaving, putting on makeup, etc. It
needs to be glare-free.
• Aesthetic: Lighting itself can be a work of art. A neon
sculpture would be purely decorative and an example of
aesthetic lighting.
35. • Tungsten: Gives off a slightly yellow tinge. These are
ordinary light bulbs.
• Spotlight: Gives a focused burst of white light.
• Halogen: Gives the closest approximation of natural
daylight, known as "white light." colours appear sharper
under halogen light. The halogen bulb is also an energy
saver. Can be dimmed.
• Fluorescent: The typical fluorescent gives a flat, cold
light, often bluish and harsh. It is a daylight-equivalent
and cannot be put on a dimmer.
36. A spectral energy distribution (SED) is a plot of brightness
or flux density versus frequency or wavelength of light.
It is used in many branches of astronomy to characterize
astronomical sources.
Galaxies emit electromagnetic radiation over the full possible
frequency/wavelength range. Analysis of these radiations is the
main means through which astronomers study the distant
galaxies and thus learns about their formation and evolution. The
distribution of energy over wavelength/frequency is called the
spectral Energy Distribution.
Spectral Energy Distribution
37. • A spectral energy distribution (SED) is a graph of the energy
emitted by an object as a function of different wavelengths.
• The graph is a typical curve, called a blackbody curve. It
shows that the amount of energy emitted by the object at all
wavelengths varies with the temperature of the object.
• Hotter objects emit more light at shorter wavelengths than
cooler objects; therefore the hotter the object, the more the
peak wavelength is shifted toward the left of the graph.
• Stars aren’t really blackbodies but the emission from them is
very similar to blackbodies. We can "fit" a blackbody curve to
the star.
38.
39. Luminous efficacy
Luminous efficacy is a measure of how well a light source
produces visible light. It is the ratio of luminous flux to power.
Depending on context, the power can be either the radiant
flux of the source's output, or it can be the total power
(electric power, chemical energy, or others) consumed by the
source.
40. Luminous efficiency:
• The effectiveness of illumination (luminous efficiency) is
defined by the ratio of the luminous flux emitted by a specific
source of light and the energy consumed by it in a time unit.
• The unit: lumen/watt (lm/W)
Examples of luminous efficiency of various light sources:
light bulb: 8-10 lm/W
halogen lamp: 16 lm/W
fluorescent lamp: 45-104 lm/W
white LED: 26-100 lm/W
metal halide lamp: 85-115 lm/W
high pressure sodium lamp: 150 lm/W
low pressure sodium lamp: 200 lm/W
41. Colour temperature
The colour temperature of a light source is the
temperature of an ideal black body radiator that radiates light
of comparable hue to that of the light source. In practice,
colour temperature is only meaningful for light sources
that do in fact correspond somewhat closely to the radiation of
some black body.
Colour temperatures over 5,000K are called cool
colours (bluish white), while lower colour temperatures
(2,700–3,000 K) are called warm colours (yellowish white
through red)
45. Lighting: For lighting building interiors, it is often important to
take into account the colour temperature of illumination.
Aquaculture: In fishkeeping, colour temperature has different
functions and foci, for different branches.
In freshwater aquaria, colour temperature is generally of concern
only for producing a more attractive display. In a
saltwater/reef aquarium, colour temperature is an essential part of
tank health.
Digital photography:In digital photography, colour
temperature is sometimes used interchangeably with white
balance, which allow a remapping of colour values to simulate
variations in ambient colour temperature
46. • Photographic film: Photographic emulsion film
sometimes appears to exaggerate the colour of the
light, as it does not adapt to lighting colour as human
visual perception does.
• Desktop publishing: In the desktop publishing industry,
it is important to know a monitor’s colour
temperature. Colour matching software, such
as coloursync will measure a monitor's colour
temperature and then adjust its settings accordingly.
47. Colour rendering index
• Colour rendering relates to the way objects
appear under a given light source. The measure is
called the "colour rendering index", or CRI.
• A low CRI indicates than objects may appear
unnatural under the source, while a light with a
high CRI rating will allow an object's colours to
appear more natural.
• For lights with a "warm" colour temperature the
reference point is an incandescent light. For lights
with a cool colour temperature the reference is
sunlight.