Luminous flux is light energy emitted by a point source. Since it depends on the distance, it is expressed in spatial angles.

Lumen is a unit of measurement of the power of light radiation, which is estimated by the sensation of light to the human eye.

Unit of measurement luminous flux Lumen can be thought of as the total amount of light. For example, a 40 W incandescent lamp will create a luminous flux corresponding to 415 lumens, a fluorescent lamp will create a flux of 3200 lumens. Place any optical system around the light source, the amount of light (lumens) will be the same. Thus, if the number of lumens is not written on a non-directional light source, then it is not clear how it will illuminate.

Illumination and brightness

Illuminance is the amount of light, it quantifies light, which falls on a particular surface area of ​​the body. It depends on the wavelength of light, because the human eye perceives the brightness of different wavelengths of light differently, in other words, different colors.

Illuminance is calculated for different wavelengths separately. People perceive the brightest colors as:

• green - light with a wavelength of 550 nanometers;
• yellow orange. They are located next to it on the spectrum.

Light coming from red, blue and purple flowers, have a short or long wavelength, so they are perceived as darker. The concept of illumination is often correlated with the concept of brightness.

When lighting an area with the same lamp, a large area will be less illuminated than a small one.

Difference between brightness and illuminance

The Russian language gives two answers to the question of what brightness is. Brightness means a characteristic of luminous bodies, that is, a physical quantity. It also defines a subjective concept that depends on many factors, for example:

• structural features of human eyes;
• amount of light in the room.

The less light there is environment, the brighter the light source appears to us. You should distinguish between brightness and illumination and remember the following:

• brightness is the light that is reflected from the surface of a luminous object;
• Illuminance is the light that falls on the illuminated surface.

In astronomy, brightness includes two concepts, where stars emit and planets reflect. In this science, stellar brightness is measured on a photometric scale, and the greater brightness of the star is correlated with a smaller value. The most negative values ​​are bright stars.

Brightness unit (candela per one) square meter) is used for applied or physiological purposes.

The lux unit is used to calculate light levels. One lux is equal to one lumen per square meter. The foot-candle is also used to measure illumination. She is consulted in the fields of cinema and photography and some others. The foot is in the name because the foot-candle means the candela illumination of a square foot of surface, measuring in one foot intervals.

Photometer

A photometer is a device that measures illumination. The light enters the photodetector, then is converted into an electrical signal and measured. There are photometers that operate on a different principle. Mostly photometers show light levels in lux, but there are also those who use other units. Those photometers, also called exposure meters, are involved in determining shutter speed and aperture, thereby helping photographers and cameramen. In addition, photometers are used to determine the level of safe illumination in other areas, for example, in crop production, in museums, where it is necessary to maintain the required illumination.

Safe flow of light at work

Working in a dark or dimly lit room can cause various health problems, be it blurred vision, depression or other physiological and psychological disorders. For this reason, in the workplace, as part of occupational safety regulations, minimum safe lighting requirements are included. IN final result The measurement produced by the photometer includes the area of ​​light propagation. These indicators ensure sufficient illumination of the entire room.

Light flux and museum exhibits

The speed at which museum exhibits will deteriorate and fade depends on the illumination and the intensity of the flow from the light source. Museum workers are working to determine the illumination of exhibits. This is done in order to ensure that there is a safe amount of luminous flux on museum units, as well as to ensure a sufficient level of illumination for visitors while viewing the exhibit.

The illumination level can be measured with a photometer, which is not easy to do because it should be installed as close to the exhibit as possible, and this requires removing the protective glass, turning off the alarm and obtaining permission. This task is made easier in another way, which is often used by museum staff. Instead of a photometer, a camera is used, which is not a replacement for a photometer in situations where more precise measurements found problem with lighting, but it is quite enough to identify a deviation from the norm.

You can determine the exposure with your camera based on the light level readings. The exposure illumination level is easy to determine using simple calculations. Museum staff resort to a formula or use a table, where exposure is represented in illuminance units. When making calculations, do not forget that the camera absorbs a certain amount of light, so you should take this into account.

Before providing a plant with the light it needs for photosynthesis, you need to know how much each crop needs. Gardeners and plant growers know this. They measure light levels to make sure each plant gets the amount of light it needs. Photometers are often used for such procedures.

Photometers are also widely used in laboratory practice. For example, a range of samples is determined with the help of which chemical composition. A special class of such devices includes a flame photometer. He detects alkali metals in samples, such as sodium, lithium, potassium. To detect them, you need to burn the sample at high temperature and use a photometer to analyze the flame spectrum. This problem is much more difficult to solve in other ways.

Modern photometers convert light radiation into electrical impulses; they are recorded using the principle of an ammeter and voltmeter, and then converted into a computer format.

A photometer is an instrument covering many fields of knowledge, such as chemistry, molecular biology, physics, materials science and others. The photometer is widely used in industry, laser and optical products. In addition to the chemical laboratory, the photometer finds application in forensic laboratories.

Thus, from the above you have learned about the units of measurement of light, which It is better to buy lamps with the specified number of lumens that the concepts of illumination and brightness differ, but the amount of light can be measured special device.

Light is simply necessary for every person to have a great mood and mental health. Thanks to it, we get the opportunity to see objects, distinguish their shape and structure of materials, because artificial extension daylight hours allows you to increase efficiency and productivity. When choosing fixtures and lamps for yourself, do not forget that the light must be selected correctly. Indoors for various purposes A variable approach to lighting intensity is acceptable. And in order to choose the right lamps, you need to know how light is measured.

and artificial

All human health experts unanimously declare that the best source of light for people is a natural light source. It promotes the production of a number of vitamins and microelements in the body, and is also most beneficial for the eyes. Each item at natural light can be seen without distortion or glare.

But unfortunately, modern world dictates its conditions, and we can no longer do without artificial light sources in the dark, otherwise the life of cities would come to a complete stop. Each apartment contains a lot various lamps, quite often we have no idea how light is measured and what we need to pay attention to in the store when buying a variety of sconces, floor lamps and lampshades.

What kind of light is there?

No less important than the selection of light intensity is the category or type of lighting. As we have already said, the most pleasant and safe light is a natural source of lighting. It has a warm tint and is least harmful to the eyes. The closest thing to a similar tone were old incandescent lamps with a reddish tint of light output. They did not irritate the eyes and copied the sunlight entering the windows of the apartments.

Modern lamps have many variations in the working element and type of light. Before purchasing a new lamp, be sure to check what type of light is indicated on the packaging. For example, warm light will be ideal for residential premises. And neutral is usually used in offices and large production premises. Cold light is often used in watchmaking workshops, where its bluish tint helps to distinguish small parts. Cold shades of light are also welcome in subtropical countries, where they create a feeling of additional coolness and transparency of the air.

Based on the above, you can always choose the right type of light bulb that will create the desired mood and level of comfort in a relaxing home atmosphere. Psychologists have proven that the type of light plays a serious role in shaping the working mood in enterprises. Naturally, labor productivity also depends on this.

What parameters are used to measure light intensity?

The average buyer does not even think about how light is measured and how much it is important information. After all, light, being measured, is measured according to many quantitative and qualitative parameters. They must be taken into account when planning renovations in the apartment and counting the number of light bulbs needed for each room.

Light can be measured according to the following characteristics:

• intensity;
• strength;
• brightness.

You won’t be able to determine all the necessary parameters just by eye, so you should take care of purchasing devices that will help you maintain your vision and a positive psychological attitude at any time of the day.

How is the brightness of light measured?

Brightness is a very important characteristic of a light source. It is the brightness of the lighting that allows us to see all the objects around us clearly and in contrast. Brightness enhances spatial perception and exposure of whites and blacks. In addition, it is the brightness of the light source that determines the degree of comfort when reading printed text, and this, as is known, directly affects eye health.

If we are talking about brightness, then remembering in what units light is measured is very easy. The candela is most often used to measure the brightness of a light source. This unit denotes the brightness of one candle, and it is from this unit that all measuring instruments are based. Sometimes experts also use other units of measurement - lambert and apostilbe.

What device can measure the brightness of lighting?

Modern specialized equipment stores are always ready to provide customers with a large number of various instruments for measuring the brightness of light. Brightness meters and colorimeters do the job best. They are able to give you information not only on the degree of brightness in a particular room, but also determine color temperature rooms.

Devices with advanced functionality are suitable for professional photographers involved in studio shooting. And for household needs, a regular brightness meter that does not have additional options is suitable.

In what

Luminous Intensity - According to school course In physics, it can be described as light energy that can be transferred from one point to another in a certain period of time. This energy can change direction depending on the given trajectory.

Light energy is measured in candelas. That is, having bought for home use brightness meter, you can always measure not only the brightness, but also the intensity of light.

Light intensity: what is it measured in?

Light intensity is often called illuminance and is also important when choosing luminaires and various types lamps Even a child can remember how light intensity is measured, although some nuances should be taken into account here.

If we are talking about something falling on a certain surface, then it is necessary to measure it in lumens. But if you want to find out the degree of illumination of objects or surfaces, you need to talk about lux.

Such subtleties often frighten buyers who have heard somewhere that light is measured in lumens, and are perplexed by the incomprehensible units of measurement indicated on the packaging of the light bulb. A very common device - a lux meter - will help you cope with the problem of determining the degree of illumination in a room.

Luxometer - a device that preserves healthy vision

If you have difficulty remembering in what units light is measured, then a lux meter will save your time and nerve cells. This device has small size and weight, most often it consists of a display and a measuring part.

You can use this assistant at home, in educational institutions or office premises. To obtain data, you just need to turn on the light source and take measurements. Within a few seconds you will see the result on the display, which will show how safe your light bulbs and lamps are for the eyes.

for apartments and other residential premises

In order to choose lighting that is comfortable for the eyes, it is not enough to know how light is measured. You also need to have information about lighting standards, which you should use when planning the location of lighting fixtures in the apartment.

Each room and space has its own required level of illumination, which is measured in lux. For example, the children's room should be the most illuminated room in the apartment. There cannot be less than two hundred suites here, otherwise the baby’s health will be at great risk.

The kitchen and other rooms can be illuminated with one hundred and fifty lux, but utility rooms and corridors can get by with fifty lux. Compliance with these standards guarantees your family a comfortable existence, excellent mood and vision that even an eagle will envy.

If you care about your family, you should know exactly what light bulbs are installed in the lamps in your apartment. After all, every sane person dreams of returning from work to a home where cheerful children and a caring wife in a good mood are waiting for him. And an important role in making the dream finally become a reality is played by well-chosen lighting.

Currently, with a huge variety of lighting devices, the population does not have a common understanding of how illumination is measured. Often there is a misunderstanding with such technical characteristics, such as luminous intensity and brightness, lumens and candelas. By purchasing lighting, often pay attention to the total luminous flux, without taking into account the loss of light and heat.

In this article:

Illumination concept

Luminous flux is measured in special laboratory conditions and it is impossible to determine it spontaneously. Therefore, SNiP takes into account the amount of illumination, which, unlike the luminous flux, everyone can measure independently. It is a measure of the ratio of luminous flux, measured in lumens, to the surface area on which photons fall. The angle of incidence should be 90°. The unit of illumination is lux.

The dependence of a person’s psychological and physical states on light has long been established. If in low light the brain processes are depressed, then in bright light they are stimulated. But in any case, the retina and the body’s resources wear out. When designing lighting devices, a safety factor (SF) is determined, which should take into account the likely decline in illumination of the installation. For artificial light The indicator provides for a decrease in brightness due to wear and tear of the optical components of the device and their natural contamination. The coefficient of natural illumination decreases due to changes in the reflective properties of surrounding objects.

Illumination measurements are carried out at workplaces along with determination of the level of pollution, sound vibrations, electromagnetic radiation, and in some industries, gamma radiation. The importance of knowing these parameters can hardly be overestimated when creating optimal working conditions, and all of them comply with sanitary rules and regulations. For example, the illumination should be:

• in the office - 300 lux;
• in the office for constant work with a computer - 500 lux;
• for technical and design bureaus - 750 lux.

If there is natural lighting in the room, the level of artificial background can be reduced.

Instruments for determining the level of illumination and methods for determining it

The name of the device is similar to the name of the value it sets - lux meter. The operating principle of a small-sized portable device resembles the operation of a photometer. The radiation flow, falling on the photosensitive element of the semiconductor, tears off electrons, which begin to move in an orderly manner. Thus, the electrical circuit is closed. Moreover, the current value is directly proportional to the intensity of illumination of the photocell, which is reflected on the scale of an analog lux meter. Today, instruments with arrows have practically disappeared, they have been replaced by digital ones. They are equipped with liquid crystal displays, in which the photosensitive sensor itself is located in a separate housing, and it is connected to the display using a flexible wire.

During the experiment to measure illumination, the device is installed in a horizontal position. Moreover, in accordance with the requirements of GOST, they are placed in different points of the room, according to a certain scheme. In 2012, Russia adopted a new standard for measuring the characteristics of the amount of luminous flux. In the old conceptual apparatus, when measuring, terms of a given quantity were used such as:

• minimum, average, maximum, cylindrical;
• natural;
• stock gradient;
• relative efficiency of coherent beam flow.

Currently, the following types of lighting have been added to them:

• emergency;
• working;
• security;
• evacuation;
• backup

The standard describes in detail all the intricacies of conducting measurement studies.

Measurements are carried out separately for natural and artificial illumination. During the experiment, it is impossible to allow even the slightest shadow to fall on the device, and there should be at least 1 source of electromagnetic waves nearby. All of them interfere with the operation of the device.

After performing the necessary illumination measurements, the required value is determined. It is compared with the standard value. Then the results are summed up about the sufficiency of illumination of the territory or room. Each type of measurement test is documented in a special evaluation protocol, which is required by GOST.

Measuring the amount of light for LED devices and examples in nature

LED lamps have become very popular due to their unique energy efficiency. But LEDs and their power supplies emit heat when illuminated, which is dissipated using heat-conducting materials (aluminum) and design features(ribs, large radiator area). Despite the apparent lack of connection between heat loss and illumination, experts always take it into account when creating new devices.

Difficulties with the operation of LED lamps begin when operating in conditions where the temperature rises above +50°C. Why is it recommended to measure the illumination of LEDs after 2 hours of their operation, i.e. after reaching optimal mode. To eliminate the occurrence of errors, repeated measurements are taken during the work shift. It is advisable to carry out these studies at least once a year. In order to eliminate any errors during design, a light reduction coefficient is set, depending on the physical characteristics of the object.

Typically, manufacturers of LED devices provide a guarantee of their flawless operation for 3 years. All operating parameters of such lamps, including illumination, must correspond to the declared values. If the operating conditions of the devices occur at outdoor temperatures above 45°C, then light measurements must be taken much more often. Otherwise, incorrect design and the results obtained will lead to a rapid drop in lighting performance.

As for examples of illumination in nature, in the Earth’s orbit and the equator at noon this value is equal to 135 thousand lux. On a sunny day it is up to 100 thousand lux, on a cloudy day it is only 1 thousand lux, but from the Moon it is only 0.2 lux. Measuring light on the street at the latitude of Moscow in winter period showed from 4 to 5 thousand lux. On a moonless night, the illumination is a thousand times less than on a full moon, and with 10-point cloudiness it is 10 thousand times less. What is used to measure the illumination in a room and natural conditions, refers to physical quantities included in the International System of Units.

Light is necessary for a person to live normally. It affects almost all aspects of his life, mental state and physiology. If lighting standards are met, the room is pleasant to be in, fatigue occurs more slowly during work. Otherwise, the mood quickly deteriorates, and other signs of the negative impact of the “wrong” light on the eyes and nervous system appear.

What is illumination

Many people confuse illumination with the brightness of lamps, but this is wrong. The same lighting fixture can create different light levels, depending on the area of ​​the room, the height of the lamp, its angle of inclination.

Brightness, or luminous flux, is measured in lumens. This indicator is on the packaging of the lighting device, but, unfortunately, it is not always reliable. Therefore, to choose energy saving lamp It makes sense to take a compact RADEX LUPIN light meter with you to the store. The same device will help measure the illumination of your workplace and rooms at home. The parameter reflects the number of lumens of luminous flux per 1 sq. m of surface. It is very important to prevent non-compliance with established standards.

What are the dangers of too little or too much lighting?

It is known that employees of some shopping centers often complain of watery eyes, fatigue and redness of the eyes. The reason is too bright lighting. On the one hand, it helps buyers get a better look at the product. On the other hand, it harms the health of the visual apparatus of workers who are under such lighting all day long.

When checking light level inspectors make orders only if the indicators do not reach the lower limits of the norm. This is because if the light is too dim, working conditions worsen. A person has difficulty doing work, his eyes get tired quickly, and myopia or farsightedness appears.

However, not only dim, but also excessively bright light is harmful to the visual apparatus. Consequences of prolonged stay in a room with too much light:

• Irritation and redness of the mucous membrane (conjunctiva).
• Feeling of dryness and “powdery” eyes.
• The appearance of irritability.
• Feeling of general discomfort.
• Nervous overexcitation.

It follows from this: it is necessary to monitor not only compliance lighting standards, but also in the absence of a significant excess of the established values.

How measure illumination on one's own

Each of us can provide ourselves comfortable conditions work and rest. In particular, by creating adequate lighting. To do this, you need to install devices that produce light of normal brightness.

Check if it meets the standard light level your room or workplace, will help lux meter RADEX LUPIN. With this device you can always determine the brightness of light in any room. The measurement is simple. Place the light meter on the control surface with the photosensor pointing upward. The parameter value will be displayed on the device monitor in lux (lx).

The RADEX LUPIN lux meter provides correct information, unlike many other models. The error of its measurements does not exceed 10%. The accuracy of the device is ensured by corrective filters that block ultraviolet and infrared rays that are not perceived by the human eye. Since the spectrum of some light sources contains both, illuminance measurement without filters it turns out inaccurate. The RADEX LUPIN lux meter meets the requirements of GOST. Its spectral sensitivity is the same as that of the human eye, so it provides complete, reliable information about the light environment.

Briefly about lighting standards

Lighting in which a person maintains working capacity for a long time and does not notice an unreasonable deterioration in well-being or mood is considered normal. For control lighting standards The Chief State Doctor of the Russian Federation approved special sanitary rules and regulations. The document establishes clear requirements for illumination of premises for various purposes.

Standards for some of them (in suites):

• Bathrooms, bathrooms - 50.
• Sleeping quarters - 100.
• Living rooms and kitchens - 150.
• Gyms - 200.
• Game rooms kindergartens - 200.
• Office rooms - 300.
• Classrooms - 300.
• Library premises - 400
• Doctors' offices and treatment rooms - 500.
• Trading rooms - 500.

The highest requirements are set for premises in which work of the highest precision is carried out. For example, for jewelry, engraving and watchmaking workshops, the illumination level should be 3000 lux. The lighting of storerooms, basements, attics, passage corridors and other rooms with short stays of people (20-30 lux) can be relatively dim.

Lighting devices differ in design, physical properties and technical characteristics. The parameters of lighting devices raise many questions and disputes, especially the unit of illumination measurement. It is often confused with other concepts, such as luminous intensity or brightness. In addition, many consumers buy lighting fixtures based on the total value, without taking into account heat and light losses.

What is illumination

The concept of illumination is closely related to the amount of luminous flux measured in laboratories using special equipment. The illumination itself can be determined independently, and its value is taken into account by the relevant SNiPs. To calculate this parameter, use the luminous flux, measured in lumens, which is in relation to the area of ​​the illuminated surface. It should hit the surface at a 90 degree angle. Illumination is measured in special units - lux (lx).

The magnitude of the luminous flux has a direct impact on the physical and psychological condition person. Too little lighting depresses the brain, and too bright, on the contrary, has a stimulating effect on brain processes. Such a negative effect causes premature wear and tear of the body and has a detrimental effect on the organs of vision.

Therefore, when drawing up a lighting design and placement of lighting devices, a safety factor must be used that takes into account the likely drop in illumination during operation. Gradually, optical components wear out and become dirty, which leads to a decrease in the brightness of artificial light. In addition, the natural light factor decreases as the reflective properties of surrounding objects gradually change.

Illumination is primarily measured at the workplace. At the same time, sound vibrations are determined, the degree of contamination, electromagnetic and even gamma radiation are taken into account. The measurement results allow you to create the most optimal conditions labor, in accordance with sanitary standards and rules.

In what units is illumination measured?

The unit of illumination measurement should be discussed in more detail. The generally accepted unit is lux, which represents the illumination when a luminous flux of 1 lumen falls on a surface of 1 m2.

How much illumination does the unit of measurement 1 lux actually include? For this purpose, it is necessary to compare several standard parameters based on human physiology, enshrined in strict medical rules and government standards. Without compliance with them, it is impossible to approve any construction project.

An illumination level of 1 lux is created by an ordinary candle located at a distance of 1 m from the illuminated surface. With the help of this simple device it is quite possible to calibrate a homemade measuring device- lux meter.

As examples for comparison, we can take several known species illumination

• Bright sunlight at noon will be 100-140 thousand lux
• Sky without clouds during the day - 6200 lux
• Desk lamp, illuminating the table - 500 lux
• Illumination in the shade on a sunny day - 430 lux
• The onset of twilight in the evening - 70 lux
• The beginning of the night with moonlight - 1.5 lux.

Light sources and surfaces that reflect light do not always appear as individual points. If the visual organs are able to distinguish their shape, then we will talk about another photometric quantity known as brightness. Her physical properties similar to the intensity of light, however in in this case this relationship will not be absolute. It is proportional to the area of ​​the reflecting or radiating surface.

Brightness, as a physical concept, is the only photometric quantity that the human eye can normally perceive. It is clearly manifested in the properties of large light sources, consisting of a large number of point emitters. Provided they are the same brightness, general light a large lighting fixture will be perceived as a single whole.

List of basic units of measurement

There are several basic units of measurement that characterize the parameters of light in one way or another. Among them, the most famous and widespread are the following:

• Light flow. Represents the power of light emitted. This is the visible spectrum of radiation associated with the sensation of light perceived by the human eye. This value is measured in lumens (lm). For example, the luminous flux emitted by a 100-watt incandescent lamp is 1350 lm, and fluorescent lamp LB40 - 3200 lm.
• The power of light. The density of the luminous flux relative to the surrounding space. At its core, it is a proportion where the luminous flux is related to the solid angle within which the radiation is uniformly distributed. The unit of measurement is candela (cd).
• Illumination. The luminous flux incident on the surface has a surface density. It is evenly distributed and correlates with the area of ​​the illuminated surface. The unit of measurement is lux (lx), equal to 1 lm/1 m2.
• Brightness. Represents the luminous intensity with surface density in a specified direction. The unit of measurement is cd/m2.
• Luminosity. The luminous flux emitted by a surface with density, which is the ratio of the luminous flux to the area of ​​the luminous surface. The unit of measurement is 1 lm/m2.

Instruments for measuring light levels

The level of illumination is measured by a device - a lux meter. This small, portable device works in much the same way as a photometer. A stream of light radiation hits a semiconductor photosensitive element and begins to tear off electrons from it, which begin to move in an orderly manner. As a result, the electrical circuit closes. In this case, the magnitude of the current is proportional to the intensity of illumination of the photocell and is displayed on the scale of analog devices.

Currently, there are practically no instruments with arrows left; they have been replaced by digital measuring equipment. Each lux meter is equipped with a liquid crystal display and a photosensitive sensor located in a separate housing. A flexible wire is used to connect these two parts together.

Before starting light measurements, the lux meter is set to a horizontal position. Modern GOST standards require that different points in the room be used for measurements in accordance with established scheme. Natural and artificial lighting measured separately. When performing the procedure, even the slightest shadow is not allowed to fall on the device. There should not be any sources of electromagnetic waves nearby. All these factors can cause interference and affect the measurement results.

The resulting illumination value must be compared with the parameter established by GOST. Based on these data, conclusions are drawn about the sufficient or insufficient illumination of any room or area. After the tests, an evaluation protocol is drawn up.

Lighting and LED fixtures

During the lighting process, LEDs generate a large amount of heat. To dissipate it, heat-conducting structures made of aluminum, cooling fins and other elements are used that neutralize the effects of heat. When creating new lamps, specialists must take into account the relationship between illumination and heat loss.

Operational difficulties appear when the temperature rises above 50 degrees. In this regard, measurements should be taken approximately two hours after the start of work. LED lamps. To eliminate errors, illumination measurements are performed periodically throughout the working day. It is recommended to conduct such studies at least once a year.