Light flow- the power of light radiation, i.e., visible radiation, assessed by the light sensation that it produces on the human eye. Luminous flux is measured in lumens.

For example, an incandescent lamp (100 W) emits a luminous flux equal to 1350 lm, and a fluorescent lamp LB40 - 3200.

One lumen is equal to the luminous flux emitted by a point isotropic source, with a luminous intensity equal to one candela, into a solid angle of one steradian (1 lm = 1 cd sr).

The total luminous flux produced by an isotropic source with a luminous intensity of one candela is equal to 4π lumens.

There is another definition: the unit of luminous flux is lumen(lm), equal to the flux emitted by an absolutely black body from an area of ​​0.5305 mm 2 at the solidification temperature of platinum (1773 ° C), or 1 candle · 1 steradian.

The power of light- the spatial density of the luminous flux, equal to the ratio of the luminous flux to the solid angle in which the radiation is uniformly distributed. The unit of luminous intensity is the candela.

Illumination- the surface density of the luminous flux falling on the surface, equal to the ratio of the luminous flux to the size of the illuminated surface, over which it is evenly distributed.

The unit of illumination is lux (lux) equal to the illumination created by the luminous flux of 1 lm, evenly distributed over an area of ​​1 m 2, i.e. equal to 1 lm / 1 m 2.

Brightness- the surface density of the luminous intensity in a given direction, equal to the ratio of the luminous intensity to the projection area of ​​the luminous surface on a plane perpendicular to the same direction.

The unit of brightness is candela per square meter (cd / m2).

Luminosity (luminosity)- the surface density of the luminous flux emitted by the surface, equal to the ratio of the luminous flux to the area of ​​the luminous surface.

The unit of luminosity is 1 lm / m2.

Light units in the international SI system (SI)

Examples:

ELECTRICAL DIRECTORY "
Under the general ed. professors MPEI V.G. Gerasimova and others.
M .: Publishing house MEI, 1998

In the past, the lighting market consisted of incandescent lamps, which required only the wattage of the fixture. Now the range of lighting elements is huge, but the most popular are LED bulbs. Some consumers, when choosing them, continue to focus on the power of the device, but this is not entirely correct, because there is another important unit.

The luminous flux characterizing is Lumen. It shows the total luminous flux of the luminaire. A person should understand that the relationship between the power and the level of illumination of a led lamp is different than in standard ones.

That is why it is necessary to correctly calculate the luminous flux of diode devices in order to provide high-quality lighting in a particular room.

When choosing bulbs, power is not the main indicator, since it shows how much energy the device spends. For example, a 60W device is weaker than a 100W device. To find out the intensity of light, you need to determine such a unit of measurement as Lm. Lumen is a more accurate indicator, since light bulbs with the same power, but different levels of efficiency (efficiency) and spectral composition, emit light of different intensities.

Lumens is a measure of the amount of light that a lighting fixture emits in different directions. This physical quantity began to be used back in the middle of the 20th century.

To determine the degree of illumination of a lamp, 2 important values ​​are used - these are lumen and lux.

Important! Lumen is a quantity that represents the total luminous flux that a lighting element emits in different directions. Lux (Lx) demonstrates the amount of light that falls on 1 m² of the surface. That is, the higher the Lx, the more illuminated the surface, and the greater the amount of Lm, the brighter the lamp.

Thus, to assess the efficiency of a light source, you need to use the following formula: 1 Lx = 1 Lm / m². For example, if a lamp with a luminous flux of 100 lumens illuminates 1 m², then the illumination will be equal to 100 lx. If the same device is used on an area of ​​10 m², then the degree of illumination will decrease. During the calculations, you need to take into account the luminous flux, which is directed in all directions.

LED bulbs emit directional light, in contrast to devices with a filament and fluorescent, which shine evenly in all directions. In order for the surface to be equally illuminated, you need to purchase LEDs with a lower brightness.

Parameters that determine the luminous flux indicator and its calculation

To buy suitable bulbs, you need to take into account not only the number of Lumens, but also the following characteristics:

• correspondence of the wavelength and temperature of light. The colorimetric temperature of 4200 K is as close as possible to natural solar radiation, so a person perceives it better. The blue and red spectrum is less desirable. The color temperature is always indicated on the product packaging or in the technical passport;

It is interesting! Cold tones of light are perceived by a person as brighter than warm ones. If you need lamps with warm radiation, then buy devices with a small power reserve in the direction of increase so that the light does not turn out to be dull.

The figure below indicates where the properties of the light flux from the source appear, corresponding to the units of measurement - lumens, candelas and lux.

Lumen, unlike candelas and suites, less commonly used units, is a measure of the total amount of light emanating from a source, the so-called. 'Luminous flux'. Something like horsepower in an engine. In fact, this is a fairly general indicator, as it does not rely on a standardized unit of measure with which it can be compared. The measure in lumens does not take into account the presence of a reflector and lens in the flashlight, the type of reflector surface, therefore it cannot serve as a description of the practical brightness of the flashlight, or its useful performance.

Candela'Luminous intensity' would be a better description of lanterns, especially those used as an everyday tool. It shows how bright a light source is in relation to how far it can be seen. To use the engine comparison again, it's like torque.

One candela- it is like one burning candle, the intensity of the glow of which, in theory, does not change, even if the light is blocked, and remains constant when viewed from different angles at the same distance. In the sense that if you look at a candle from any angle at a distance of 20 meters, its brightness will be constant. So the candela is not only a descriptive characteristic, it is a real measure of the flashlight's capabilities.

Also candela refers to the measurement of a focused beam of light, while lumen refers to the total amount of light emitted. One lumen is equal to the luminous flux emitted by a source with a luminous intensity of one candela - this is in an intentionally simplified form without important details.

Suite however, ‘illumination’ is a measure of the amount of light falling on a surface of a given area. Lux is equal to the illumination of a surface of 1 sq. m. with a luminous flux of radiation incident on it, equal to 1 lumen. So this measure is relative to the surface that you intend to illuminate.

If it’s still too complicated, let’s draw the line: compare lumens to lumens, and candela to candela. If you are comparing two different products, described by different units of measurement, then calculate the ratio, the Internet is full of calculators and tables.

The choice of units in which the flashlight is evaluated depends on how you intend to use the flashlight. If you want to illuminate an area with flood light, then such a flashlight is best evaluated in lumens. Candelas are better suited to characterize a concentrated beam like a searchlight. One is suitable for illuminating spaces and viewing rooms, the other and individual illumination of targets.

In addition to distinguishing between different units of measurement, it is important to understand that more is not necessarily better. One of the reasons for this is the limited field of view of a person, and when you illuminate a space larger than your vision and consciousness can process, this is hardly beneficial. This kind of highlighting can give you away, or highlight someone you would rather not highlight. When examining a room, you need to light it up, but you do not need the rays of light to penetrate the street through the cracks. until you find the bad guy.

There are additional considerations when deciding which flashlight to invest in. And buying a sturdy, reliable flashlight is a serious investment. Choosing for price and looks rather than looking at user experience is easy to miscalculate. Well-known manufacturers with a good reputation provide the best guarantee, service, and ultimately - uptime, but the name of the company alone should not be defining.

There is a rule for this category of equipment: “ Two is one, and one is nothing!". Even if you have a spare battery or a spare light bulb, chances are that your main headlamp will run into problems and need to use a spare. Your comrades get very annoyed when you constantly borrow from them.

There is a lot of controversy about which type of battery is best. If you don't change the battery (or charge the battery) before each exit, you need a spare flashlight.

The photo below shows batteries of standard sizes: 10430 (analogue of AAA battery), 14500 (analogue of AA battery), 16340 (analogue of CR123 battery), 18650, 26500 (analogue of battery C):

Putting your flashlight to the test before leaving the door will save you a lot of headache. Additional options can include adjustable focus, strobe, and different types of light sources. Some flashlights change modes with a few clicks of one button.

While adjustable focus can be useful for indoor inspections, rescue operations, and so on, the reality of high-intensity combat will not allow this feature to be used. The same applies to switching modes with a tricky combination of short and long presses on the button.

Most people I know prefer not to rely on fine motor skills to deal with stress. Such manipulations, with precisely calibrated repeated presses, are very difficult to practice.

In general, a lot of nuances affect the effectiveness of the use of a flashlight. In recent years, there has been a leap forward in lens and light source technology. After a quick and easy replacement of the light module, the old lantern is literally transformed, becoming modern, powerful and economical.

Equally important, in addition to having a good flashlight, is also. The use of a flashlight on a weapon, together with a weapon, and everyday needs make this issue very relevant, so training is the key to success.

A is an occupation that requires a fair amount of enlightenment. Shine! =)

Instructions

According to the definition, an illumination of one lux creates a luminous flux of one lumen if it evenly illuminates a surface with an area of ​​one square meter. Therefore, to convert lumens to suites, use the formula:

Klux = Klumen / Km²

To convert suites to lumens, apply the formula:

Klumen = Klux * Km²,

Where:
Klux - illumination (number of lux);
Klumen - value (amount of lumens);
Km² - illuminated area (in square meters).

When calculating, keep in mind that the lighting should be uniform. In practice, it is that all points on the surface must be equidistant from the light source. In this case, the light must hit all areas of the surface at the same angle. Also note that the entire flux emitted by the light source must hit the surface.

If the light source is close in shape to a point light, then uniform illumination can be achieved only on the inner surface of the sphere. However, if the luminaire is sufficiently distant from the illuminated surface, and the surface itself is relatively flat and has a small area, then the illumination can be considered almost uniform. A "striking" example of such a light source can be considered, which, due to its great distance, is an almost point light source.

Example: In the center of a 10 meter high cubic room there is a 100 W incandescent lamp.

Question: what will be the illumination of the ceiling of the room?

Solution: a 100 watt incandescent lamp generates a luminous flux of approximately 1300 lumens (lm). This stream is distributed over six equal surfaces (walls, floor and ceiling) with a total area of ​​600 m². Therefore, their illumination (average) will be: 1300/600 = 2.167 Lx. Accordingly, the average illumination of the ceiling will also be equal to 2.167 Lx.

To solve the inverse problem (determining the luminous flux for a given illumination and surface area), simply multiply the illumination by the area.

However, in practice, the luminous flux created by a light source is not calculated in this way, but is measured using special devices - spherical photometers and photometric goniometers. But since most light sources have standard characteristics, use the following table for practical calculations:

Incandescent lamp 60 W (220 V) - 500 lm.
Incandescent lamp 100 W (220 V) - 1300 lm.
Fluorescent lamp 26 W (220 V) - 1600 lm.
Sodium gas discharge lamp (outdoor) - 10,000 ... 20,000 lm.
Low pressure sodium lamps - 200 Lm / W.
LEDs - about 100 Lm / W.
Sun - 3.8 * 10 ^ 28 Lm.

Lm / W is an indicator of the efficiency of a light source. So, for example, a 5 W LED will provide a luminous flux of 500 lm. Which corresponds to a 60W incandescent lamp!

Lux, lumens, kelvin, watts - what do these basic technical terms mean, which are used in the characteristics of LED and other lamps used for lighting?

Knowing these basic technical terms will help you when choosing LED luminaires.

First, let's figure it out how does the LED work which is used as a light source in LED luminaires.

The incandescent lamps we are accustomed to glow because the electric current that passes through the thinnest filament made of refractory metal (usually tungsten) heats it up to such a temperature that it begins to emit light.

Note: Tungsten is the most refractory metal. Its melting point is 3422 ° C, boiling point is 5555 ° C. The photosphere of the Sun has about the same temperature.

The light studied by the LED, is the result of the movement of electrons in a special semiconductor material. Modern technologies make it possible to create LEDs with a service life of up to 20 years (more than 35,000 hours).

During recombination (exchange), energy is released in the form of photons.

To convert a stream of photons into visible light, the material is selected so that the wavelength of the photons is within the visible region of the color spectrum with a wavelength of 700 to 400 nm.

Definitions

Light flow - quantitative characteristic of the radiation that is emitted by the light source. Unit of measurement - (lm, English lm)

In simple words:

Light flow is the total amount of light that a given light source emits.

The power of light- the ratio of the luminous flux directed from the light source within the elementary spatial angle (1 steradian), covering the given direction, to this angle. Unit of measurement - (cd)

In simple words: The power of light is the luminous flux density

Illumination is the surface density of the luminous flux incident on a unit surface. Unit of measurement - (lx, eng.lx).

In simple words:

Illumination directly proportional to the intensity of the light. That is, with distance from the surface, the illumination decreases and vice versa - the closer the light source is to the surface (light bulb), the less powerful it should be. Usually horizontal illumination (in the horizontal plane) is normalized.

Lighting power - the magnitude of the brightness of the illumination per unit area, i.e. received light. For example, the brightness of sunlight reaches 100,000 Lux, in the shade - 10,000 Lux, in an illuminated room - about 300 Lux

Color sensation - a general, subjective feeling that a person experiences when looking at a light source. Light can be perceived as warm white, neutral white, cool white. The objective impression of the color of the light source is determined by the color temperature measured in (TO)

Brightness is the ratio of the intensity of light emitted by an object in a given direction to the projection of the surface of this object onto a plane perpendicular to this direction. Brightness is directly related to the level of visual sensation, and the distribution of brightness in the field of view (for example, in the interior) characterizes the quality (or the degree of comfort, convenience) of lighting. Unit of measurement - cd / m2

Integrated driver - it means that the ballast is an integral part of the electronic circuit of the luminaire (i.e. it is placed on the same board with the light source)

Units

Watt(W, eng. W) - the amount of energy consumed. unit of measurement W (W)
With regard to lighting, the number of watts indicated by the manufacturer on the packaging does not characterize the brightness of the device, not the amount of light that the light bulb will emit, but only the amount of electricity that the source (light bulb) uses in one hour of operation.

To understand exactly how much light a light bulb gives, it would be more correct to pay attention to the number of lumens or candelas.

When buying conventional incandescent lamps, the number of watts indicated on the light bulb label determines how brightly it will shine. But for LEDs, this indicator has a completely different meaning, because they are completely different.

But you can still draw a parallel between the brightness of incandescent lamps and LED lamps, focusing only on power. There are even special comparison tables for this.

The easiest way converting power to lumens for a conventional incandescent lamp:

We multiply the number of watts by 10 to get the approximate number of lumens.

for example If you need as much light as a typical 60W lamp, look for a lamp with roughly 600 lumens. This can be an LED lamp with a power of approximately 8-12 watts.

This is clearly seen in the above comparison table.

Lumen(lm, English - lm) is a unit of measurement of the luminous flux of a light source. It determines the amount of light emitted by the light source.

One lumen (1 lm) is the luminous flux that is emitted in a unit solid angle of 1 steradian, an equally directional point source located in the center of a sphere of unit radius, and having an intensity 1 candela... (1lm = 1cd * sr). Light source with luminous flux in 1 lm uniformly illuminating the surface 1 sq.m creates illumination 1 suite.

In simple words:

Lumens determine how much light a lamp emits in all directions. The more light, the greater the number of lumens. This should be considered when choosing an LED lamp. The lumen for a light bulb is similar to a liter for a container, kilograms for a weight product, or meters for a linear one. Those. An LED light with more lumens will give a brighter light (as a larger volume will hold more water). Fewer lumens will give less light.

But the brightness and the number of lumens can vary greatly. Other characteristics such as color temperature, brightness, illumination and luminous intensity should also be considered.

It is also worth remembering that Lumen is full light flow from the source. And this measurement usually does not take into account the focusing efficiency of a reflector or lens, and therefore is not a direct parameter for evaluating the brightness or useful performance of a luminaire beam. A wide beam of light can have the same lumen as a narrow beam.

Lumens cannot be used to determine the intensity of a beam because the lumen estimate includes all scattered and useless light.

Suite is the unit of illumination used in the SI system. Lux is equal to the illumination of a 1 sq.m. with a luminous flux from a source of 1 lm (Lm / m 2).

In simple words:

If you collect 100 lumens and project them onto an area of ​​1 square meter, then the illumination index of this area will be 100 lux. And if a similar luminous flux of 100 lumens is directed over 10 square meters, then the illumination will be only 10 lux.

Interesting: The human eye is a very sensitive organ that senses illumination as strong as 0.001 lux. This value can be compared to a candle flame, which the human eye can recognize at a distance of 1 km.

Phot- unit of illumination in the CGS system. Equal to 10,000 lux.

Candela(cd, cd - from lat. candela- candle) - a unit of measurement of luminous intensity. One candela (1 cd) equal to the intensity of the light that one candle emits.

Candelas are used to measure light coming in one direction, for example for mirror lamps. The more light, the more candelas. Candela complies with the standard that is included in the International System of Basic Units (SI).

Kelvin - K ◦ ... Indicator color temperature- characteristics of the distribution of the radiation intensity of the light source as a function of the wavelength in the optical range. The temperature of a blackbody at which it gives off radiation with the same chromaticity as the given radiation. Color temperature characterizes the spectral composition of the light source.

In simple words:

Kelvin (C) is a characteristic of light sources that determines the color of the lamps and the color tone (warm, neutral and cold) of the space illuminated by the lamps. Expressed in Kelvin (K) temperature scale.

The full spectrum of illumination is emitted by the Sun and consists of various wavelengths. In combination, they are white or yellow, depending on the time of day, but individually they have different colors. These parameters refer to the color spectrum of the lamp. The color temperature of light (K) in Kelvin does not indicate the spectral composition of the lamp's light - it shows how the human eye perceives the color of light from a given lamp. This is a characteristic associated precisely with perception. The lower the color temperature, the more red and less blue. The higher the color temperature, the greater the proportion of blue and green. White is in the range 5500-6500K. Below 5500K, the light from the lamp becomes yellow or orange. And at values ​​above 6500K - blue.

2700-3000K- warm light - radiation predominates in the red part of the spectrum

4000-4200K- cold light - radiation is distributed over the entire spectrum

5200-6500K- daylight - radiation predominates in the blue part of the spectrum

8000-25000K - ultraviolet radiation

Note:

Kelvin (K)- a unit of thermodynamic temperature, one Kelvin is equal to 1 / 273.16 of the thermodynamic temperature of the triple point of water
Triple point of water- temperature 273.16 K and pressure 61.1657 Pa, at which water can simultaneously and in equilibrium exist in the form of three phases - in solid, liquid and gaseous states.

Color temperature scale for common light sources