What is the Lighting ? Light is that part of the electromagnetic spectrum that is perceived by our eyes. The wavelength range is between 380 and 780 nm.
Light has a triple effect
Light for visual functions
– Illumination of task area in conformity with relevant standards
– Glare-free and convenient
Light creating biological effects
– Supporting people’s circadian rhythm
– Stimulating or relaxing
Light for emotional perception
– Lighting enhancing architecture
– Creating scenes and effects
Basic parameters used in lighting
- Luminous flux Φ
The luminous flux describes the quantity of light emitted by a light source. The luminous efficiency is the ratio of the luminous flux to the electrical power consumed (lm/W). It is a measure of a light source’s economic efficiency.
Abbreviation: Φ Phi , Unit: lm Lumen
- Luminous intensity Ι
The luminous intensity describes the quantity of light that is radiated in a particular
direction. This is a useful measurement for directive lighting elements such as reflectors. It is represented by the luminous intensity distribution curve (LDC).
Abbreviation : Ι Unit: cd Candela
- Illuminance E
Illuminance describes the quantity of luminous flux falling on a surface. It decreases by the square of the distance (inverse square law). Relevant standards specify the required illuminance (e.g. EN 12464 “Lighting of indoor workplaces”).
Illuminance: E(lx) = luminous flux (lm)
area (m2)
Abbreviation: E Unit: lx Lux
- Luminance L
Luminance is the only basic lighting parameter that is perceived by the eye. It specifies the brightness of a surface and is essentially dependent on its reflectance (finish and color).
Abbreviation: L Unit: cd/m2
Ω = solid angle into which luminous flux is emitted
A = area hit by luminous flux
AL · cos ६= visible areas of light source
ρ = reflectance of areaп = 3.14
* = for diffuse surface areas
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