Lighting Fundamentals PDF

28/10/2023 Fundamentals: lighting LIGHT radiant energy that is capable of 3 F...

28/10/2023 Fundamentals: lighting LIGHT radiant energy that is capable of 3 Fundamentals exciting the human retina and creating a visual sensation 1 2 Fundamentals: LIGHT As a physical quantity, light is defined in RADIANT FLUX is terms of its relative efficiency throughout the term given to the electromagnetic spectrum lying the total power of between approximately 380 & 780 nm electromagnetic RADIANT FLUX RADIANT FLUX radiation (measured in watts) emitted or RADIANT RADIANT received FLUX FLUX RADIANT FLUX 3 11 Fundamentals: Fundamentals: Radiant flux which The unit of contains those luminous flux wavelengths is termed the RADIANT RADIANT RADIANT RADIANT which are FLUX FLUX LUMEN. FLUX FLUX detectable by the human eye is said to have a RADIANT RADIANT RADIANT RADIANT corresponding FLUX FLUX FLUX FLUX value of RADIANT RADIANT LUMINOUS FLUX. FLUX FLUX LUMINOUS FLUX LUMINOUS FLUX 12 13 1  28/10/2023 Fundamentals: Fundamentals: Illuminance (symbol E) is the term given to the Luminance (symbol L) is the luminous intensity quantity of luminous flux falling on unit area of a emitted by a light source per unit area. surface. It is measured in candela per square metre. It is measured in lux, which is equivalent to lumens per square metre. 15 16 Fundamentals: Fundamentals: OPTICAL CONTROL: REFLECTION & REFLECTORS Optical control may be provided in a number of Reflection is the process by which a part of the light phenomena: falling on a medium leaves that medium from the incident side. REFLECTION Reflection may be: REFRACTION Specular Spread INTERFERENCE Diffuse or compound DIFFRACTION Selective or nonselective DIFFUSION ABSORPTION 17 18 Fundamentals: Fundamentals: REFLECTION & REFLECTORS REFLECTION & REFLECTORS SPECULAR SPREAD If a surface is polished, it reflects specularly; that is, If a reflecting surface is not the angle between the reflected ray and the normal smooth (that is, corrugated, to the surface will equal the angle between the etched, or hammered), it spreads incident ray and the normal parallel rays into a cone of reflected rays 19 20 2  28/10/2023 Fundamentals: Fundamentals: REFLECTION & REFLECTORS REFLECTION & REFLECTORS DIFFUSE COMPOUND If a material has a rough Reflectors that exhibit all three surface or is composed of reflection components minute crystals or pigment (specular, spread, and diffuse) particles, the reflection is diffuse to varying degrees 21 22 Fundamentals: REFLECTANCE SURFACE COLOR REFLECTANCE FACTORS: FACTOR % White 70-85 REFRACTION & REFRACTORS Light Gray 45-65 Surface Color Medium Gray 25-40 A change in the velocity of Dark Gray 10-20 light (speed of propagation, Black 5 not frequency) occurs when Yellow 65-75 a ray leaves one material Yellowish Brown 30-50 and enters another of Dark Brown 10-25 greater or lower optical Light Green 30-55 density. The speed will be Dark Green 10-25 reduced if the medium Pink 45-60 Light Red 25-35 entered is denser, and Dark Red 10-20 increased if it is less dense. Light Blue 30-55 Dark Blue 10-25 23 24 REFLECTANCE SURFACE MATERIAL REFLECTANCE Fundamentals: FACTORS: FACTOR % Lacquer, Brilliant White 87-88 Aluminium, high-gloss 75-87 INTERFERENCE Surface Color Aluminium, mat 75-84 Sound Absorbing Ceiling, white 60-80 When two light waves of the Marble, white 60-70 same wavelength come Mortar, light 35-50 together at different phases Concrete, light 30-40 of their vibration, they Concrete, dark 15-25 combine to make up a single Sandstone, light 30-40 wave whose amplitude is Sandstone, dark 15-25 between the difference and Granite 15-25 the sum of the amplitudes of Brick, light 20-30 the two, depending on their Brick, dark 10-15 relative phase Wood, light 30-50 Wood Dark 10-25 25 26 3  28/10/2023 Fundamentals: Fundamentals: DIFFRACTION DIFFUSION A phenomena that occurs when light passes by an The breaking up of a beam of light and the obstruction, producing an indistinct, rather than spreading of its rays in many directions by irregular sharp, shadow of the edge reflection and refraction from microscopic crystalline particles, droplets or bubbles within a transmitting medium, or from microscopic irregularities of a reflecting surface. 27 28 Fundamentals: ABSORPTION Occurs when a light beam passes through a transparent or translucent medium or meets a dense body such as an opaque reflector surface. 29 4