To deal with light pollution, we need to know information about lighting and the mechanism of light production (light physics). For this reason, we refer to some concepts of light engineering here…
Not every light source emits an equal amount of light in all directions, but in each direction specified by the Candela power factor, it defines the amount of light in that direction. In fact, it can be said that the amount of light in a particular direction or the intensity of radiance is determined by the candelabra.
Light intensity with Kandel (Candela) is measured. Candlepower is usually used to determine the intensity of light in different directions of a light source.
Candlepower Distribution Curve *
A curve (usually a pole) that represents changes in the luminosity of a lamp or light fixture from the center of the light source.
Brightness Luminance is the intensity of light that reaches our eyes directly from the source. Glare When a glowing object is placed in our field of vision, the image created in our eye usually appears brighter than after the eye has adapted.
*Light intensity (Illuminance)
* 1 is actually the density of the luminous flux on the surface, which is measured by a unit (Footcandle) orluxuryLux is measured in metric units. The usual form of this property is Illuminance.
Illuminance * 2 is actually to measure the amount of luminous flux property that appears on the surface. Illuminance is affected by the intensity of light stabilization in the direction of the surface and the distance of the light source from the surface and the intersection angle of the light reaching the surface. However, the intensity of light is a factor that can not be measured with the naked eye, but is the most common criterion in optical designs.
is the basic unit of usury for measuring light. A candle on the dinner table emits light of about 12 lumens and a 60-watt white bulb with more power of about 855 lumens.
If we have a point light source of a candle in the center of Korea with a radius of one foot that has an opening of about one square foot on its surface, it is similar to a lamp that emits a lumen of light.
Light intensity: lumen
The light flux passing through the space angle unit (estradian) is called the light intensity, which is measured in terms of the candela. The spatial angle is the angle that is seen from the center of a sphere and covers its surface. The size of the spatial angle is equal to the ratio of the size of the surface to the square of the radius of the sphere. The intensity of light in any part of space is independent of the distance and proximity to the light source to the same extent, but in different directions it has different values.
Lumen: The amount of visible light received from a light source or the amount of light flux emitted from each Stardian space angle.
Luminance Luminance intensity (photometric brightness) of each surface in a specific direction per unit of the surface observed in the same direction, measured in Candela / m ^ 2. Luminous flux is the size of all the light produced by a light source. It is the amount of light that leaves the surface of an object regardless of its direction. A typical 100-watt neon lamp emits about 1,700 lumens, and a 400-watt high-pressure sodium vapor lamp emits about 50,000 lumens. The luminous flux rate of each lamp is provided by its manufacturers, and a list of the lumens of ordinary lamps can be found in the Lamp Matrix.
Luminous intensity (Candelas) Luminous
intensity is the intensity of light that is emitted in a certain direction. In fact, the luminous intensity of an optical system is determined by special graphical diagrams called Candela power change curves. Both polar and Cartesian diagrams are used in the optical industry for this purpose. This information is usually available in digital tables.
is the unit of measurement of illuminance in a metric device. And in fact the amount of light located on a square meter is where the uniform light flux is one Shine on it. In fact, 10.76 lux equals one foot candle. One luxury is equal to 0.09 Foot candle. And one deluxe equals ten luxuries
1-76 / 10 Lux = 1 Foot candle
2- 1 Lux = 09/0 Foot candle
3- 1 Deluxe = 10 Lux
The surface density of a light flux radiating to a surface is called the intensity of light, which is measured in terms of lux. The amount of light intensity required for different applications is recommended in the references. These suggestions are based on the precision of the complexity of the tasks to be performed.
For example, for simple tasks such as walking in the hallway, the required light is 120 lux, and for tasks such as assembling machines and very small tools, where human vision is very important, high light intensity of about 1000 lux is required.
* Lux :
The unit of light intensity is expressed in lux, and one lux is the unit of light produced from the uniform light flow of a candle at the level of one square meter.
Light intensity In some familiar places,
street level 30 lux
living room 100 luxury
study room 300 luxury
land surface in winter sun 10000 luxury
land surface in summer sun 100000 lux
* Light flux
The luminous flux represents the rate of light emission from a light source and is measured in lumens.
That is, if a point source of light, with the intensity of a candle, is located in the center of the sphere within a radius of one meter,
A surface of one square meter inside the sphere will receive a luminous flux equal to one lumen. The higher the lumen produced by a light source per watt of input power, the more efficient the light source.
* Distribution light intensity The light scattering curve in polar coordinates shows the amount of light intensity of a lamp or lamp on a screen that passes exactly through the center of the lamp or lamp.
The intensity of light at different angles around a lamp is shown in a table. Because in many cases the light intensity distribution around a lamp is not symmetrical, they draw a light intensity curve for different planes. The three common plates are the plate perpendicular to the axis of the lamp, the plate parallel to the axis of the lamp, and the plate at an angle of 45 degrees to the axis of the lamp. After selecting the pages, the light intensity curve of each page can be prepared. Lamps and combinations Lamps and lights each have their own unique curve. The light intensity curve depends on the design of the lamp, the material of the lamp cover and the type of ballast.
is the ratio of the intensity of the light of the source (or object reflecting light) to the area of the radiant part of the source (or the area of the part of the object that reflects light).
Luminosity is measured in terms of candela per square meter (style) or candela per square centimeter (intention). Suitable brightness for the human eye is in the range of 65 to 6500 nits.
Luminosity or density of light: If two light sources that have the same light intensity but different physical size, if the light is seen in a row, the smaller source looks brighter. The unit of luminosity of a candle is per square meter (intention). A candle is 60 times smaller than the intensity of light emitted from a square centimeter of the surface of a black body at a temperature of 2045 K in a direction perpendicular to the surface.
Describes the relationship between light output and input power. Productivity is expressed in lumens per watt. The maximum efficiency is 680 lumens per watt, which is from a hypothetical lamp that has no losses and all its radiation in A wavelength of 0.555 microns is obtained. In the case of incandescent lamps, 8 to 20 lumens per watt have the lowest efficiency among lamps, for fluorescent lamps up to about 90 lumens per watt, for mercury lamps up to about 50 lumens per watt and for sodium lamps up to more than 100 Lumens per watt have the highest efficiency among lamps.
* Input power density:
The amount of power used for lighting purposes in a certain range or in the whole building is defined and is expressed in watts per unit area w / m2
Color temperature (Kelvin):
Color temperature is defined based on the color emitted by a black body at a certain temperature and is expressed in degrees Kelvin. Color temperature above 4000 K is considered as cold light and color temperature below 3000 K is considered as warm light.