Illumination Presentation PDF

INTRODUCTION TO ILLUMINATION Presented by Group 1 HISTORY AND BACKGROUND  HISTORY The earliest artificial lighting sources include campfires, torches, primitive oil lamps, fireflies, chandeliers, and kerosine. Fire was first ignited in the caves of Peking Man 400,000 years ago,...

INTRODUCTION TO ILLUMINATION Presented by Group 1 HISTORY AND BACKGROUND  HISTORY The earliest artificial lighting sources include campfires, torches, primitive oil lamps, fireflies, chandeliers, and kerosine. Fire was first ignited in the caves of Peking Man 400,000 years ago, and primitive oil lamps were used by prehistoric people 15,000 years ago in Lascauxe Caves in France. In the 1840s, Canadian geologist Abraham Gesner introduced kerosine, allowing for brighter light at a lower cost. This led to a decline in whale oil use, which eventually declined with the discovery of crude oil in 1859. Electric lighting, including arc lights and incandescent bulbs, became widespread in developed countries in the 1880s. This led to the disappearance of segmented sleep patterns, improved nighttime lighting, and reduced urban crime. Principles of Illumination 1. Luminous Flux 2. Luminous Intensity 3. Illumination 4. Luminance LUMINOUS FLUX Luminous flux, or luminous power, is the measure of the perceived power of light. It differs from the measure of the total power of light emitted, termed ‘radiant flux’, in that the former takes into account the varying sensitivity of the human eye to different wavelengths of light. In other words, it is photometrically weighted radiant flux (power) UNIT OF LUMINOUS FLUX The SI unit of luminous flux is the lumen (lm). The lumen is defined in relation to the candela which is the unit of luminous intensity as 1 lm = 1 cd ⋅ sr That is, when the luminous angle of a light source is one solid angle and the luminous flux is 1 lumen, its luminous intensity is 1 candela. When the luminous flux of a light source is also 1 lumen, but the luminous angle becomes 1/2 solid angle, the luminous intensity of this light source is considered to be 2 candelas. Conversely, when the luminous intensity of a point light source that emits light in all directions is 1 candela, as a full sphere has a solid angle of 4π steradians, the luminous flux of this light source is 4π lumens, or 12.56 lumens. LUMINOUS INTENSITY In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function. Photometry deals with the measurement of visible light as perceived by human eyes. The human eye can see light only in the visible spectrum, and has different sensitivities to light of different wavelengths within the spectrum. When adapted for bright conditions (photopic vision), the eye is most sensitive to greenish-yellow light at 555 nm. LUMINOSITY FUNCTION The luminosity function describes the relative sensitivity of human eyes to light of different wavelengths by subjectively judging the brightness of light of different colors. It shouldn’t be considered perfectly accurate, but it is a good representation of visual sensitivity of the human eye and it is valuable as a baseline for experimental purposes. LUMINOUS INTENSITY CALCULATIONS The minimum luminous intensity of lights shall be calculated by using the formula: I=3.43×106×T×D2×K−D where I is luminous intensity in candelas under service conditions, T is threshold factor 2 × 10−7 lux, D is range of visibility (luminous range) of the light in nautical miles, K is atmospheric transmissivity. For prescribed lights the value of K shall be 0.8, corresponding to a meteorological visibility of approximately 13 nautical miles. ILLUMINATION illumination of a surface is defined as the luminous flux received by the surface per unit area. It is represented by the symbol and measured in lux (or metre candle or lumen/m^2) Illumination, The unit of illumination is lux. PROPERTIES OF ILLUMINATION Understanding these properties is crucial in various domains, including architecture, photography, stage lighting, and interior design. Let us delve into these fundamental aspects of illumination: Color Temperature: Color temperature measures the visual appearance of light, indicating whether it is warm or cool in nature. Distribution: Distribution refers to the spread or direction of light in a space, achieved through specific lighting fixtures and techniques. Direction: Direction of illumination defines the angle at which light falls on an object or surface, creating various effects and highlighting features. Contrast: Contrast in illumination is the difference in light levels between different areas, resulting in pronounced shadows and dramatic effects. Color Rendering: Color rendering measures how accurately a light source reproduces colors compared to natural sunlight, crucial in settings where color accuracy matters. Energy Efficiency: Energy efficiency is essential in lighting, promoting the use of energy- efficient alternatives like LED bulbs to reduce consumption and increase lifespan. ILLUMINATION CALCULATIONS LUMINANCE In simple words, luminance is the intensity of the emitted light from a surface per unit area in a particular direction that can be considered for its definition. It provides the amount of light that passes through, is reflected, and falls within a given solid angle. The SI unit of Luminance is candela per square meter (cd/m2). The measure of the total light output of a luminous source is known as Luminous Flux. DIFFERENCE OF TWO TERMS Illuminance Luminance ILLUMINANCE REFERS TO THE AMOUNT OF LIGHT LUMINANCE REFERS TO THE AMOUNT OF LIGHT FALLING ONTO A GIVEN SURFACE AREA. PASSING THROUGH AN OBJECT THE BEST WAY TO EXPLAIN THE DIFFERENCE BETWEEN THE TERMS IS THROUGH AN EXAMPLE. IMAGINE A LIT-UP STREETLIGHT. THE AMOUNT OF LIGHT THAT PASSES THROUGH THE LIGHTBULB REFERS TO THE LUMINANCE. ON THE OTHER HAND, THE AMOUNT OF LIGHT THAT HITS THE STREET BELOW IS ILLUMINANCE. WE MEASURE ILLUMINANCE IN LUX USING AN ILLUMINANCE METER. LUMINANCE FACTORS The luminance of the surface depends on the following factors. 1. Nature of the surface. 2. The Luminous flux that is incident on the unit area of the surface. LUMINANCE FORMULA TERMS USED (1) Light: It is defined as the radiant energy from a hot body which produces the visual sensation upon the human eye. It is usually denoted by Q, expressed in lumen-hours and is analogous to watt- hours. (2) Luminous Flux: It is defined as the total quantity of light energy emitted per second from a luminous body. It is represented by symbol F and is measured in lumens (or cd-sr). The conception of luminous flux helps us to specify the output and efficiency of a given light source. (3) Luminous Intensity: Luminous intensity in any given direction is the luminous flux emitted by the source per unit solid angle, measured in the direction in which the intensity is required. It is denoted by symbol I and is measured in candela (cd) or lumens per steradian. (4) Lumen: The lumen is the unit of luminous flux and is defined as the amount of luminous flux given out in a space represented by one unit of solid angle by a source having an intensity of one candle power in all directions. (5) Candle Power: Candle power is the light radiating capacity of a source in a given direction and is defined as the number of lumens given out by the source in a unit solid angle in a given direction. It is denoted by symbol CP. (6) Illumination: When the light falls upon any surface, the phenomenon is called the illumination. It is defined as the number of lumens, falling on the surface, per unit area. It is denoted by symbol E and is measured in lumens per square metre or lux or metre-candle. (7) Lux or Metre-Candle: It is the unit of illumination and is defined as the luminous flux falling per square metre on the surface which is everywhere perpendicular to the rays of light from a source of one candle power and one metre away from it. (8) Foot-Candle: It is also the unit of illumination and is defined as the luminous flux falling per square foot on the surface which is everywhere perpendicular to the rays of light from a source of one candle power and one foot away from it. (9) Candela: It is the unit of luminous intensity. It is defined as 1/60th of the luminous intensity per cm2 of a black body radiator at the temperature of solidification of platinum (2,043 K). (10) Mean Horizontal Candle Power (MHCP): It is defined as the mean of candle powers in all directions in the horizontal plane containing the source of light. (11) Mean Spherical Candle Power (MSCP): It is defined as the mean of candle powers in all directions and in all planes from the source of light. (12) Mean Hemispherical Candle Power (MHSCP): It is defined as the mean of candle powers in all directions above or below the horizontal plane passing through the source of light. (13) Reduction Factor: Reduction factor of a source of light is the ratio of its mean spherical candle power to its mean horizontal candle power. (14) Lamp Efficiency: It is defined as the ratio of the lumi­nous flux to the power input. It is expressed in lumens per watt. (15) Specific Consumption: It is defined as the ratio of the power input to the average candle power. It is expressed in watts per candela. (16) Brightness or Luminance: When the eye receives a great deal of light from an object we say it is bright, and ‘brightness’ is an important quantity in illumination. It is all the same whether the light is produced by the object or merely reflected from it. (17) Glare: The size of the opening of the pupil in the human eye is controlled by its iris. If the eye is exposed to a very bright source of light, the iris automatically contracts in order to reduce to amount of light admitted and prevent damage to retina ; this reduces the sensitivity, so that other objects within the field of vision can be only imperfectly seen. 18) Space-height Ratio: It is defined as the ratio of horizontal distance between adjacent lamps and height of their mountings. (19) Utilization Factor or Coefficient of Utilization: It is defined as the ratio of total lumens reaching the working plane to total lumens given out by the lamp. (20) Maintenance Factor: Due to accumulation of dust, dirt and smoke on the lamps, they emit less light than that they emit when they are new ones and similarly the walls and ceilings, etc., after being covered with dust, dirt and smoke do not reflect the same output of light, which is reflected when they are new. (21) Depreciation Factor: This is merely the inverse of the maintenance factor and is defined as the ratio of initial metre- candles to the ultimate maintained metre-candles on the working plane. Its value is more than unity. (22) Waste Light Factor: Whenever a surface is illuminated by a number of sources of light, there is always a certain amount of waste of light on account of overlapping and falling of light outside the edges of the surface. (23) Absorption Factor: In the places where atmosphere is full of smoke fumes, such as in foundries, there is a possibility of absorption of light. (24) Beam Factor: The ratio of lumens in the beam of a projector to the lumens given out by lamps is called the beam factor. This factor takes into account the absorption of light by reflector and front glass of the projector lamp. (25) Reflection Factor: When a ray of light impinges on a surface it is reflected from the surface at an angle of incidence. The ratio of reflected light to the incident light is called the ‘reflection factor‘. It is always less than unity. (26) Solid Angle: Plane angle is subtended at a point in a plane by two converging straight lines and its magnitude is given by (27) Steradian: It is the unit of solid angle and is defined as the solid angle that subtends a surface on the sphere equivalent to the square of the radius. SITES AND LINKS https://en.wikipedia.org/wiki/Lighting#:~:text=Lighting%20or%20illumination%20is%20the,natural%20illumination%20by%20capturing %20daylight. (history and background) https://testbook.com/electrical-engineering/illumination-definition-and- terms#:~:text=illumination%20of%20a%20surface%20is,pronounced%20shadows%20and%20dramatic%20effects. (Definition of Illumination) https://www.youtube.com/watch? v=Zr55SrNAV7I&si=mpNuOMK1rNkO5DVa&fbclid=IwZXh0bgNhZW0CMTEAAR2NIKZM5mmLD4UAD__bW64GH7blKS0dwnXl- Ndq7F3vlKC4dHw36nN6H_8_aem_PGzpfp_DFiT0b5ZlgWvmuQ (ptinciples of Illumination) https://www.yujiintl.com/understanding-luminous-flux-lumen-and-illuminance- lux/#:~:text=We%20often%20see%20luminous%20flux,What's%20the%20difference%20between%20them? (luminous flux) https://www.sciencedirect.com/topics/engineering/luminous- intensity#:~:text=Luminous%20intensity%20is%20the%20basic,expressed%20in%20candela%20(cd). (Luminous Intensity) https://byjus.com/physics/luminance/#:~:text=The%20apparent%20brightness%20of%20an,unit%20area%20of%20the%20surface. (Luminance) https://gamma-sci.com/2020/02/18/luminance-vs-illuminance-what-is-the- difference/#:~:text=It's%20essential%20to%20understand%20the,March%205%2C%202021 (difference between Luminance and Illumination) https://testbook.com/electrical-engineering/illumination-definition-and- terms#:~:text=illumination%20of%20a%20surface%20is,pronounced%20shadows%20and%20dramatic%20effects. (Illumination) https://www.eeeguide.com/what-is-illumination-terms-used-in-illumination/? fbclid=IwZXh0bgNhZW0CMTEAAR3wAFoZ1ydvK0hmoAudNibSt_WqqpCsk6I4Hf29pCDEiZufv0tQE6c_RO8_aem_K4ZWjCc0iJLxajALyUEE BQ (terms used in Illumination THANK YOU