Illumination is measured in lumens. Luminous flux of LED lamps

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 lux, which are 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. It's actually a fairly general metric because it doesn't rely on a standardized unit of measurement to compare it to. The lumen measurement does not take into account the presence of a reflector and lens in a flashlight, or the type of surface of the reflector, and therefore cannot serve as a description of the practical brightness of the flashlight, or its useful performance.

Candela, ‘light intensity’, would be a better description of lanterns, especially those used as an everyday tool. It shows how bright the light source is relative to how far away it can be seen. If we again use the comparison with the engine, it’s like torque.

One candela- it’s like one burning candle, the intensity of the glow of which, in theory, does not change, even if an obstacle is placed to the light, and remains constant when observed 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 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 equal to one candela - this is in a deliberately simplified form without important details.

Lux same, ‘illuminance’ is a measure of the amount of light falling on the surface of a given area. Lux is equal to the illumination of a surface area 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 you intend to illuminate.

If this is still too complicated, then let’s draw the line: compare lumens with lumens, and candelas with candelas. 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 unit of measurement in which a flashlight is rated depends on how you intend to use the flashlight. If you want to illuminate an area with flood light, then this type of flashlight is best rated in lumens. Candelas are better suited for the concentrated beam characteristics of a search light. One is suitable for illuminating spaces and inspecting rooms, the other for individual illumination of targets.

In addition to differentiating between different units of measurement, it is important to understand that bigger is not necessarily better. One of the reasons for this is that a person has a limited field of vision, and when you illuminate a larger space than your vision and consciousness can process, it is hardly beneficial. This kind of lighting can give you away, or highlight someone you would rather not highlight. When inspecting a room, you need to light it, but you don’t want rays of light shining through the cracks into the street. until you find the bad guy.

There are additional considerations when deciding which flashlight to invest in. And buying a strong, reliable flashlight is a serious investment. If you choose by price and appearance, and without studying the user experience, it’s easy to make a mistake. Well-known manufacturers with a good reputation provide the best warranty, service, and ultimately performance, but the company name alone should not be decisive.

For this category of equipment there is a rule: “ Two is one, and one is nothing!". Even if you have a spare battery or a spare bulb, chances are your main flashlight will have problems and you'll need to use a spare. It really annoys your comrades when you constantly borrow money from them.

There is a lot of debate about which type of battery is better. If you don't change the battery (or charge the battery) before every trip, you'll need a spare light.

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

Testing your flashlight before heading out the door will save you a lot of headaches. Additional options may include adjustable focus, strobe, and different types of light sources. Some flashlights change modes with just a few presses of one button.

While adjustable focus may be useful for indoor inspections, rescue missions, etc., the reality of high-intensity combat does not allow for this feature. The same applies to switching modes with a tricky combination of short and long button presses.

Most people I know prefer not to rely on fine motor skills to function under stress. Such manipulations, with precisely calibrated multiple clicks, are very difficult to practice.

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

No less 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 activity that requires a fair amount of enlightenment. Shine on! =)

Lumen (lm, lm)- unit of measurement of luminous flux in SI. Where SI is the system of units of physical quantities (French: Le Syst?me International d'Unit?s, SI).

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 created by an isotropic source with a luminous intensity of one candela is equal to 4? lumens.

A typical 100 W incandescent lamp produces a luminous flux of approximately 1300 lm. A 26 W compact fluorescent fluorescent lamp produces a luminous flux of approximately 1600 lm. The luminous flux of the Sun is 3.63·10 to the 28th power of lm.

Lumen is the total luminous flux from a source. However, this measurement usually does not take into account the focusing efficiency of the reflector or lens and is therefore not a direct parameter for assessing the brightness or useful performance of the beam. A wide beam of light can have the same lumens as a narrowly focused beam. Lumens cannot be used to determine beam intensity because the lumen rating includes all scattered wasted light.

Lux (lx)- unit of measurement of illumination in the SI system.

Lux is equal to the illumination of a surface with an area of ​​1 sq. m when the luminous flux of radiation incident on it is equal to 1 lumen.

100 lumens were collected and projected onto a 1-meter square area. The illumination of the area will be 100 lux. The same 100 lumens aimed at 10 square meters will produce 10 lux of illumination.

Candela (cd, cd)- one of the seven basic units of measurement of the SI system, equal to the intensity of light emitted in a given direction by a source of monochromatic radiation with a frequency of 540·10 to the 12th power of Hz, the energy intensity of which in this direction is (1/683) W/sr. Steradian (Russian designation: ср, international: sr) is a unit of measurement of solid angles.

The selected frequency corresponds to the color green. The human eye is most sensitive in this region of the spectrum. If the radiation has a different frequency, then greater energy intensity is required to achieve the same light intensity.

Previously, candela was defined as the intensity of light emitted by a black body perpendicular to a surface with an area of ​​1/60 sq. cm at the melting point of platinum (2042.5 K). In the modern definition, the coefficient of 1/683 is chosen so that the new definition matches the old one.

The intensity of light emitted by a candle is approximately equal to one candela (Latin candela - candle), so this unit of measurement was previously called a “candle”, now this name is outdated and is not used.

Luminous intensity of typical sources:

Black Diamond is a trendsetter in the world of professional mountaineering and climbing equipment. The brand produces high-quality headlamps and pendant lamps that can be used even at a depth of one meter underwater for half an hour. BD offers travel lighting with up to 200 lumens of light output and a relatively light weight. Many flashlights are equipped with several lighting modes for ease of use on the mountaineering route and at home. Bright, light, neat and practical, BlackDiamond flashlights will not let you down even in the most extreme situations.

Luminous flux of lamps (lm)

big LED-high, big LED-med, big LED-low, 5 MM - High, 5 MM - medium, 5 MM - low

When choosing an LED lamp, pay attention to the lumens to ensure the amount of light you need.

We usually buy things based on the quantity we need, right? When we buy milk, we buy it in liters. Then why should it be different with light? For decades, we've bought light bulbs based on how much energy they use (watts)—and without regard to how much light they give us (lumens).

Lumen measures how much light you get from a light bulb. The more lumens, the brighter the light. Fewer lumens produce less light.

But brightness and lumens can vary greatly, so there is a certain way to calculate the appropriate specifications.

Practical calculation method:

• to replace a 100-watt incandescent bulb, look for an LED bulb that produces 1,100 lumens;
• 75-watt lamp - about 750 lumens;
• 60-watt lamp - about 550 lumens;
• A 40-watt lamp is about 200 lumens.

If you need something less bright, purchase LED bulbs with fewer lumens.

Lighting efficiency:

But we must not forget that Lumen is the total light flux from the source. However, this measurement usually does not take into account the focusing efficiency of the reflector or lens and is therefore not a direct parameter for assessing the brightness or useful beam performance of a luminaire. A wide beam of light can have the same lumens as a narrowly focused beam. Lumens cannot be used to determine the intensity of a beam because the lumen rating includes all scattered and wasted light.

Lux is a unit of measurement of illumination.

For example, 1 Lux is equal to the illumination of a surface with an area of ​​1 m² when the luminous flux of radiation incident on it is equal to 1 lumen. If you collect 100 lumens and project them onto an area of ​​1 m², the illumination of that area will be 100 lux. If the same 100 lumens are directed at 10 m², the illumination will be 10 lux.

Label for LED lamps:

What should be on the packaging when you buy LED lighting fixtures?

To help consumers better understand the transition from watts to lumens, the Federal Trade Commission has proposed a new label for LED bulbs. This label will help people buy light bulbs that are right for them.

Just like food labels, lighting labels can help consumers understand what they are really buying. The label clearly indicates: luminous flux, type of bulb, price, estimated cost of operation per year and color of the glow from warm white (with a yellowish tint) to cool white to cold (with a blue tint).

In Soviet times, when choosing a light bulb, consumers were guided by the number of watts in it. The more of them, the brighter the device shone. However, today (when many new varieties of lamps have appeared on store shelves) we are increasingly faced with such a concept as “lumen”. What is it, how does it differ from a watt, and what is the unit called lumen per watt? Let's find answers to these questions.

What is "lumen"

In the middle of the twentieth century. To avoid confusion in units of measurement between different countries, the universal SI system was introduced. It is thanks to her that we have watts, amperes, meters, kilograms, etc.

According to it, (visible electromagnetic radiation) is In fact, these units measure the amount of light emanating from its source.

Also, to the question of what “lumen” is, you can answer that this is the name of a famous Russian rock band from Ufa. Having started its activities in 1998, it has continued to be loved by many listeners in the Russian Federation and abroad for almost twenty years.

Origin of the word

Having learned what a lumen is, it is worth clarifying where this word came from in the Russian language.

Like most SI unit names, the term in question is a Latinism. It is derived from the word “light” (lūmen).

At the same time, some linguists argue that the noun could be formed from the Proto-Indo-European word leuk (white) or from lucmen (the meaning is not precisely established).

What is the difference between lumen and lux

Considering the meaning of the word “lumen”, it is worth mentioning such a close concept as “lux”.

Both of these terms refer to light energy units, but lumen is the entire light emitted by a source, and lux is the amount of light that reached the illuminated surface and was not stopped by some obstacles to form shadows.

The interdependence of these units can be reflected with the following formula: 1 lux = 1 lumen/1 square meter.

For example, if a lamp illuminating an area measuring 1 m 2 emits 50 lumens, then the illumination of this place is equal to 50 lux (50 lm / 1 m 2 = 50 lux).

However, if the same lamp with the same amount of light is used for a room of 10 m2, then the illumination in it will be less than in the previous case. A total of 5 lux (50lm/10m2 = 5 lux).

In addition, such calculations did not take into account the presence of various obstacles that prevent light rays from reaching the surface, which significantly reduces the level of illumination.

Due to this situation, in every country in the world there are lighting standards for various buildings. If it is lower than them, a person’s vision does not receive enough light and deteriorates. For this reason, when planning to make repairs or rearrangements in your home, it is always important to take this nuance into account.

There are also a number of design programs in which such calculations are made automatically.

Lumen and Watt

Having learned the difference and meaning of lumen and lux, it is worth paying attention to another SI unit - the watt.

Because they are used for light bulbs, some believe that these units can be freely related to each other. However, this is not quite true.

The fact is that the power of energy that a light bulb consumes is measured in watts, and the amount of light that it emits is measured in lumens.

In the days when only incandescent lamps existed, it was easier to calculate the amount of light from such a device. Since a 100 W bulb produced about 1600 lumens of light. While a similar 60 W device produces 800 lm. It turned out that the more energy consumed, the better the lighting.

But today everything is different. In recent decades, several new types of lighting sources have been invented (fluorescent, etc.). Their advantage is cost-effectiveness. That is, they shine brighter with less energy used.

In this regard, if it is necessary to create a relationship between watts and lumens, you need to take into account the type of lamp and look for its aperture in special tables.

It is worth noting that an ordinary person sometimes does not want to rebuild and understand all these subtleties. Therefore, most domestic manufacturers of new types of light bulbs indicate on the labels not only the number of lumens, but how much less watts the device consumes (compared to an incandescent lamp). For example: a 12-watt lamp produces the same light as 75 watts.

Unit of measurement “lumen per watt”: its meaning and scope of application

For example, a classic 40 W incandescent lamp has a light output of 10.4 lm/W. At the same time, for an induction lamp with the same power this figure is much higher - 90 lm/W.

For this reason, when choosing a lighting device for your home, you should not be lazy, but find out the level of its light output. As a rule, such data is on the labels.

Light is something without which nothing on Earth would be able to exist. Like all physical quantities, it can be calculated, which means there is a unit of measurement for luminous flux. What is it called and what is it equal to? Let's find answers to these questions.

What is "luminous flux" called?

First of all, it is worth understanding what this term is called in physics.

Luminous flux is the power of light emission, assessed by the light sensation it produces from the point of view of the human eye. This is a quantitative characteristic of the radiation of a light source.

The numerically considered quantity is equal to the energy of the light flux passing through a certain surface per unit time.

Luminous flux unit

How is the physical quantity in question measured?

According to the current SI (International System of Units) standards, a specialized unit called a lumen is used for this.

This word was derived from the Latin noun meaning "light" - lūmen. By the way, this word also gave rise to the name of the secret organization “Illuminati,” which became a subject of general interest several years ago.

In 1960, the lumen officially began to be used throughout the world as a unit of measurement of luminous flux, and remains so to this day.

In abbreviated form in Russian, this unit is written as “lm”, and in English - lm.

It is worth noting that in many countries the light power of light bulbs is measured not in watts (as in the vast expanses of the former USSR), but rather in lumens. In other words, overseas consumers consider not the amount of energy consumed, but the strength of the light emitted.

By the way, because of this, the packaging of most modern energy-saving light bulbs contains information about their characteristics in both watts and lumens.

Formula

The unit of measurement of luminous flux under consideration is numerically equal to light from a point isotropic source (with a force of candela) emitted into a solid angle equal to one steradian.

In the form of a formula, it looks like this: 1 lm = 1 cd x 1 avg.

If we take into account that a complete sphere forms a solid angle of 4P sr, it turns out that the total luminous flux of the above source with a power of one candela is equal to 4P lm.

What is "candela"

Having learned what a lumen is, you should pay attention to the unit associated with it. We are talking about CD - that is, candela.

This name was derived from the Latin word for “candle” (candela). From 1979 to this day it is according to the SI (International System of Units).

In fact, one candela is the intensity of light emitted by one candle (hence the name). It is worth noting that in the Russian language for a long time, instead of the term “candela”, the word “candle” was used. However, this name is outdated.

From the previous paragraph it is clear that lumen and candela are related (1 lm = 1 cd x 1 sr).

Lumens and Luxes

When considering the features of such a light value as a lumen, it is worth paying attention to such a close concept as “lux” (lx).

Like candelas and lumens, lux is also a lighting unit. Lux is a unit of illumination used in the SI system.

The relationship between lux and lumen is as follows: 1 lux is equal to 1 lm of luminous flux, evenly distributed over a surface of 1 square meter. Thus, in addition to the above lumen formula (1 lm = 1 cd x 1 sr), this unit has one more: 1 lm = 1 lx/m2.

In simpler terms, a lumen is an indicator of the amount of light emitted by a certain source, for example, the same light bulb. But lux shows how light the room really is, since not all light rays reach the illuminated surface. In other words, lumen is the light that came out of the source, lux is the amount of it that actually reached the illuminated surface.

As already mentioned, not all the emitted light always reaches the illuminated surface, because often in the path of such rays there are obstacles that create shadows. And the more there are on the way, the less illumination there is.

For example, when the library hall was built, many light bulbs were hung in it. The total illumination of this empty room was 250 lux. But when the renovation work was completed and furniture was brought into the hall, the light level dropped to 200 lux. This is despite the fact that the light bulbs, as before, produced the same amount of lumens of light energy. However, in the path of each of its rays, obstacles now appeared in the form of shelves with books and other library furniture, as well as visitors and workers. Thus, they absorbed part of the emitted light, reducing the total amount of illumination to the hall.

The situation given as an example is not an exception of its kind. Therefore, when constructing any new buildings or decorating the interior of existing ones, it is always important to take into account its illumination. Most institutions even have a system of lighting standards; naturally, it is measured in lux.

In the modern world, there are several programs in which you can not only simulate the design of your room yourself, but also calculate how light it will be. After all, the vision of its inhabitants depends on this.

Lumen and Watt

In the past, in our country, when choosing a light bulb, we were guided by the number of watts it consumes. The more of them, the better the light of this device.
Today, even in our country, radiation power is increasingly measured in lumens. In this regard, some believe that lm and W are quantities of the same kind, which means that lumens to watts and vice versa can be freely converted, like some other SI units.

This opinion is not entirely correct. The fact is that both units of measurement under consideration are used for different quantities. So, a watt is not a light unit, but an energy unit that shows the power of a lighting source. While lumen shows how much light a particular device emits.

For example, a regular incandescent lamp that consumes 100 watts produces 1340 lumens of light. At the same time, its more advanced (today) LED “sister” produces 1000 lm while consuming only 13 W. Thus, it turns out that the light intensity of a light bulb is not always directly dependent on the amount and power of energy absorbed by it. The substance used for lighting in the device also plays an important role in this matter. This means that there is no direct relationship between lumens and watts.

Moreover, these quantities are really related to each other. The luminous efficiency of any light source (the relationship between the energy consumed and the amount of light produced) is measured in lumens per watt (lm/W). It is this unit that is evidence of the effectiveness of a particular lighting device, as well as its efficiency.

It is worth noting that if necessary, it is still possible to convert lumens to watts and vice versa. But for this you need to take into account several additional nuances.

• The nature of the light source. Which lamp is used in the calculations: incandescent, LED, mercury, halogen, fluorescent, etc.
• Light output of the device (how much watt it consumes and how many lumens it produces).

However, in order not to complicate your life, to carry out such calculations, you can simply use an online calculator or download a similar program to your computer or other device.

Multiples of Lumen Units

Lumen, like all its “relatives” in the SI system, has a number of standard multiples and submultiples. Some are used for ease of calculation when one has to deal with either too small or too large values.

If we are talking about the latter, then they are written in the form of a positive degree, if about the former - in the form of a negative one. Thus, the largest multiple unit of lumen - iottalumen - is equal to 10 24 lm. It is most often used to characterize cosmic bodies. For example, the luminous flux of the Sun is 36300 Ilm.

The most commonly used units are four multiples: kilolumen (10 3), megalumen (10 6), gigalumen (10 9) and teralumen (10 12).

Lumen subunits

The smallest subunit of a lumen is the ioctolumen - ilm (10 -24), however, like the iottalumen, it is practically not used in real calculations.

The most commonly used units are millilumen (10 -3), microlumen (10 -6) and nanolumen (10 -9).