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1 nit [nt] = 1 candela per square meter [cd/m²]

Initial value

Converted value

candela per square meter candela per square centimeter candela per square foot candela per square inch kilocandela per square meter stilb lumens per square foot meter per steradian lumen per sq. centimeter per steradian lumen per square foot non steradian nit millinite lambert millilambert foot-lambert apostilbe blondel shaved cattle

More about brightness

General information

illumination

Brightness is a photometric quantity equal to the ratio of the intensity of light emitted by a surface to the area of ​​its projection onto a plane perpendicular to the observation axis. The amount of light here is measured as the energy emitted by a light source or reflected by an illuminated surface. Brightness is the amount of light emitted or reflected, which is different from the total amount of light in a room, from the amount of light directed towards a surface (illuminance), or from the total amount of light emitted at a particular solid angle (luminous intensity).

Basically, the difference between lightness and brightness is clear, but in order not to confuse these two concepts, you can remember them as:

1. brightness = light, reflected from the surface
2. illumination = light, heading to the surface

Brightness can refer to two concepts: the physical property of light described above, and the subjective concept of how bright an illuminated object or light source appears to be. Each person perceives brightness differently, depending on a number of factors, such as individual vision. The brightness of surrounding objects and the environment also affects how bright the light source or the object that reflects the light appears. Therefore, in the description of light sources, the concept of brightness is used, which means not a subjective but a physical quantity. This value is used in evaluating the brightness of displays such as TV screens or digital clock. Brightness is also important for our perception of works of art and the world around us.

Physiology of brightness perception

The photoreceptors of the eye, rods and cones, are most sensitive to light with a wavelength of 550 nanometers (green light). Sensitivity decreases with increasing or decreasing wavelength. Thanks to this sensitivity, green, and the colors that are next to it in the spectrum (yellow and orange), seem to us the most vivid. That is, brightness is the property of light to appear bright or dim, depending on how the brain processes wavelength information.

People, like other animals, adapt to environmental conditions, and if in environment there is no change, then people get used to it and stop noticing it, since it does not pose a danger. So it is with the perception of brightness. People get used to the brightness in the environment and judge the brightness of objects depending on the brightness of the environment. For example, screen cell phone with the same brightness appears bright at night and dim during the day. This is because at night our eyes get used to the darkness, and therefore a greater difference between the screen and the environment means more brightness for us. A smaller difference between daylight and the screen means less brightness, even though the screen's brightness doesn't actually change.

Contrast sensitivity

Contrast sensitivity is the ability of the eye to see the difference between the brightness of objects. This sensitivity is especially important in cases where this contrast is reduced due to lighting, such as in fog, in the dark, or when the brightness and color of nearby objects are close. People with low sensitivity usually find it difficult to drive at night or in fog, drive in the dark, or see if glare is in the way. Low contrast sensitivity is especially problematic for people who also suffer from color blindness.

Contrast sensitivity deteriorates with age, as well as due to a number of diseases, such as glaucoma, cataracts, myocardial infarction, or diabetic retinopathy, that is, damage to the retina due to diabetes. The problem with contrast sensitivity is independent of visual impairment, and often occurs in people with excellent vision, although sometimes both vision and contrast sensitivity deteriorate at the same time. Contrast sensitivity testing differs from vision testing in that it can be done with glasses or contact lenses if the person is wearing them. Everyday life. Instead of a table with letters of different sizes, the patient is offered a table with letters whose contrast is reduced. In a more complicated version, the table does not show letters, but lines on different backgrounds, and the task is complicated by the fact that light can also be directed into the eye to impair visibility.

Special spectacles tailored to the patient based on the results of an eye test often help improve contrast sensitivity. This check is similar to the tests that are done before laser surgery. By the way, laser surgery for the correction of other visual defects sometimes helps to increase contrast sensitivity, although in some cases, on the contrary, worsens it, as side effect. It is not uncommon to improve the sensitivity by wearing glasses with yellow lenses.

Brightness in art and design

Optical illusions and effects

Artists often manipulate brightness to achieve some effect or illusion. For example, if the brightness of the color of two nearby objects is the same, then their line of contact seems blurry. Artists use this property to depict the illusion of movement. One of the most famous examples is Monet's painting. "Impression. Rising Sun" on the illustration. Here the illusion of a shimmering sun and a sun path is caused precisely by this property - the brightness of the sun and the sky surrounding it, as well as the brightness of the sun path and the sea, are very close. Color and brightness are processed by different parts of the brain. The department responsible for brightness is also responsible for location, perspective, and movement. Due to the different colors, the brain understands that an object of a different color exists, but due to the same brightness, it cannot determine where it is, so an illusion of trembling or movement is created. This technique can be used, for example, to create the illusion of shining stars in the evening sky.

In photography, this effect is also often used. When shooting a sunset, the photographer waits for the moment when the sun or clouds become the same brightness, but different colors from the sky. If you manage to capture this moment, then sometimes it seems that the sun or clouds flicker in the photo.

Such colors are found in nature not only at sunset and dawn. A similar combination of flowers can be found both in the meadow and in the flower bed. For example, the tulips in the photo seem to sway slightly, due to the fact that their brightness merges with the brightness of the grass. This is clearly seen in black and white photography.

In some cases, this combination of colors can be creepy. The orange lights in the castle appear to be flickering in the photo, as they are the same brightness as the castle walls. If their color is changed to red and darken the surrounding sky, then the fortress continues to flicker, but it no longer looks like a hospitable palace, but an ominous haunted castle.

On the other hand, the use of colors with contrasting brightness, such as a combination of bright and dark colors, gives the image volume, as on a pink camellia painted in oil. The flower looks so voluminous that you want to run your hand over it to make sure of it - although in fact the drawing was made on a plane. It is more difficult to convey contrast with dark colors than with light ones - this is clearly seen in the picture with camellia and is especially noticeable in the black and white image. The light flower goes from almost white to dark red, and looks voluminous. Dark leaves have much less difference in contrast than the flower and appear flatter. The convenience of working with light colors to convey contrast was noticed by Leonardo da Vinci, and many artists work in this technique.

Design

The goal of most artists is to make the viewer think, to evoke different feelings in him. For this, various effects are used, such as those described above. In design, on the other hand, clarity is more important than special effects. This is especially important on signs such as road signs or hazard warnings. In order for those who are intended to understand this message as well as possible, designers use contrasting colors, with a large difference in brightness between the message and the background. This makes the text or image more visible.

	The brightness of the text almost matches the brightness of the background
So the text is hard to read.	So the text is hard to read.

The difference in contrast makes text readable and small details stand out. If, on the contrary, there is little difference in contrast between the text or images and the background, then the text or images are hard to see and start to dance in front of the eyes. The figure shows exactly such text, which is poorly readable due to the fact that although it differs in color from the background, it merges with it in brightness.

As the color saturation decreases, the readability of the text deteriorates. In our text example, red is more like the background in terms of brightness than green, but more saturated. Therefore, it reads a little better, despite the fact that green differs more from the background in its brightness. In order to make the text as readable as possible, the difference in brightness between it and the background is maximized, and the saturation is also increased.

If the design uses several colors with different brightness, then the largest contrast between the brightness of the background and text should be done for the most important text. The rest of the text can be less contrasted, and the least significant - with the lowest difference in brightness.

On a lighter background, it is easier to see the difference between two images with different brightness, so in order to increase the contrast, it is desirable to lighten the background. This doesn't always work, as it doesn't help people who have to be in very bright environments, like pilots. You also need to be careful when choosing a text color if the background changes frequently, such as on navigator maps. Also keep in mind that design for displays is limited by the range of colors that can be reproduced by the display.

Brightness and aerial perspective

If you look far away, then objects that are farther from the observer, such as mountains, appear brighter and blurry. The contrast and saturation of colors also decreases. Artists use this feature to convey perspective. That is, the elements of the landscape in the background are drawn lighter and blurry. This effect is called "air perspective" - ​​it is caused by the scattering of light by water and other particles in the atmosphere.

In foggy or wet weather, the number of water particles in the atmosphere increases dramatically, and the effect of aerial perspective occurs even with objects that are close to the observer. The brain perceives this phenomenon as a normal perspective, and it seems to a person that these objects are further away than they really are. This is very dangerous for both pedestrians crossing the road and for drivers, and one must be aware of this and be especially careful in fog.

Do you find it difficult to translate units of measurement from one language to another? Colleagues are ready to help you. Post a question to TCTerms and within a few minutes you will receive an answer.

Calculations for converting units in the converter " Brightness Converter' are performed using the functions of unitconversion.org .

Brightness. The brightness of monitors is measured in standard SI units: candela per square meter (cd/m²)

The brightness of monitors is measured in standard SI units: candela per square meter (cd/m²). Sometimes this unit is called "nit" (from French). The brightness of monitors is measured using a special device - a photometer, which takes into account the peculiarities of human perception. The fact is that our eye perceives the brightness of different colors in completely different ways, that is, the sensitivity of the eye for different shades varies.

Humans are much more sensitive to the brightness of 550nm (green) light than longer red wavelengths (700nm) or shorter blue wavelengths (400nm). Therefore, the photometer calculates brightness as a function of the wavelength of the light.

The maximum brightness of conventional monitors is about 500 cd/m². For comparison, a 60 W incandescent lamp has a brightness of 90,000 cd/m². A phosphor that glows in the dark - 0.03 cd / m².

But keep in mind that a different brightness level is recommended for each type of activity. In general, the brightness of the monitor should be set depending on the illumination of the room. In darkened rooms, it is better to reduce the brightness, and in well-lit rooms, increase it.

Don't buy into high level declared brightness: it is much more important for TVs that you will watch from afar than for monitors with a panel located at a distance of 30-40 cm from your eyes.

For work. When editing office documents, it is best not to exceed the level of 150-200 cd / m², otherwise the eyes will quickly begin to tire.

For professional imaging brightness is adjusted in such a way as to provide best quality color rendering, color gamut and contrast. To do this, use a special tool - a calibrator.

For multimedia and games. In a bright room, the brightness can be increased to 250-300 cd / m², and in a dark room - reduced to 150 cd / m². General rule: The farther away the audience is from the monitor, the higher the brightness should be. Therefore, if you watch a movie in a company, then the brightness needs to be increased.

Ministry of Education of the Russian Federation

Volgograd State Technical University

Department of "Technical operation and repair of vehicles"

SEMESTER WORK

in the discipline "Fundamentals of scientific research"

Theme: "Brightness"

Option: 75

Student: Melikhov Vladimir Alexandrovich

Group: AT-312

Direction: 5521 "Operation of vehicles"

Lecturer: Zotov Nikolai Mikhailovich

Date of submission for verification: ___________

Student painting: ___________

Volgograd 2003

Brightness characteristic……………………………………………………….3

Methods, sensors and devices used to measure brightness and their principles of operation……………………………………………………………8

Examples of brightness measurement in the production, testing, diagnosis, maintenance and repair of vehicles or their elements…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

References………………………………………………………...12

Luminance characteristic

The brightness of a radiating surface in astronomy and in physics is defined in the same way. This concept is applicable only for extended (non-point) sources, since it contains the area of ​​the radiating surface. Since the light intensity decreases in proportion to the square of the distance to the source, and the solid angle at which the projection of the radiating area is visible also decreases according to the same law, the brightness of the source does not depend on the distance to it and is often measured in astronomy as a flux from 1 sq. seconds of the arc of the visible surface of the source or as the illumination created by such a section of the visible surface of the source.

If you try to give a definition of brightness, then it may sound like this:

Brightness is a photometric quantity that characterizes the emissivity of extended bodies in a given direction.

The brightness of a body in a given direction is determined by the energy radiated per unit time within a unit solid angle by an element of the body's surface, the projection of which onto a plane perpendicular to the chosen direction has a unit area. The unit of brightness in the International System of Units (SI) is 1 candela per square meter - the brightness of a surface, each square meter of which radiates in a direction perpendicular to it within an angle of 1 steradian flux equal to 1 lumen. In astronomy, brightness is often measured by the apparent magnitude surface area of ​​one square second of arc. Previously, in the International System of Units (SI), 1 nit was taken as a unit of brightness (1 nt \u003d 10cd / m 2).

For example, the brightness of the night sky is about 21.6 square seconds of arc, that is, about 2 10 -4 nt, the brightness of the visible surface of the Sun is about 150,000 square seconds of arc (about 1.4 nt), and the average brightness of the full moon is about 0.25 square seconds arc (about 2.3·10 -6 nt).

If we approach the definition of brightness from the point of view of physical meaning, then we can give the following definition: Surface brightness- light flow d F outgoing from the platform dS in the considered direction, referred to the unit of the solid angle and to the unit of the apparent size of the area, i.e. dS cos q :

,

where dZ = d F/ d W– site light intensity dS(Fig. 1). Letter AT provided with an index q, since the brightness depends on the angle q, under which the site is considered dS .

When considering the total luminous flux sent by a unit of a luminous surface in one direction, it is necessary to introduce such a concept as luminosity

luminosity To called the total luminous flux sent by a unit of a luminous surface in one direction, i.e., in a solid angle W =2 p. The unit for luminosity in the International System of Units (SI) is the same as the unit for illuminance, that is, lumens per square meter (lm/m2). Since the luminous flux from a unit surface to a solid angle d W equals d F= B q cos q d W, then

(1.15)

For surfaces emitting according to Lambert's law (i.e. surface brightness does not depend on the direction of radiation), the brightness AT q =B does not depend on the angle q, that's why

K= p AT

Since the luminous flux, which also characterizes the brightness, is primarily perceived by a person through the organs of vision, that is, the eyes, it is necessary to consider how it is perceived by a person. Exposure to light causes irritation of the retina. From the retina, excitation is transmitted to optic nerve and further into the brain, causing a sensation of light. The property of visual sensation, according to which objects appear to emit more or less light, is called lightness . As we already know, only certain fractions of the entire light energy emitted by objects into the surrounding space reach the retina. They are expressed as brightness . Thus, the intensity of light stimulation is determined by the values ​​of brightness, and the intensity of light sensation - by the values ​​of lightness. The greater the brightness, the greater the lightness. Therefore, we can say that lightness is a measure of the sensation of brightness.

In everyday life, a clear distinction is often not made between the concepts of brightness and lightness, but when studying the visual perception of light, they must be clearly distinguished. Brightness is an objective value, it can be measured with an appropriate device (you guessed it, it is called a brightness meter). Lightness is a subjective value, like all sensations. For example, a sheet of white paper in sunlight in summer has a brightness of about 30,000 nits, and under the light of a table lamp - about 10–30 nits. However, no one will say that the same sheet of paper is lighter in one case than in another. Among a number of features of visual perception, its ability to separate the characteristics of illumination from the characteristics of the illuminated object is manifested here. This phenomenon belongs to the category of psychological, and, in particular, is associated with memory.

It follows from what has been said that lightness cannot be directly measured and expressed in absolute numbers. However, a quantitative assessment is possible, expressed in words: more, less, equal, much more or less, hardly different. Moreover, these expressions can quite definitely be compared with the differences in the measured brightnesses. In this way, the dependence of sensation on stimulation can be studied.

In the middle of the last century, the German physicist Wilhelm Eduard Weber (1804-1891) set up experiments in order to find the relationship between the magnitudes of irritation and sensation. In 1851 Weber discovered a law that is common to all sense organs: and a given amount of irritation (brightness of light, weight, sound intensity, etc.) is a measure of how noticeable its change is.

Simply put, the measure of sensually perceived differences is not the minimum value of the difference between two stimuli when given level irritation, but a relative value that remains unchanged when the irritation changes.

Later, in 1858, Gustav Fechner (1801–1887, German physicist and physician) conducted experiments on visual discrimination of brightness. He found that in the case of luminances, the ratio DP/P is constant over a large practical range of luminances. Fechner derived a mathematical formula for the dependence of a change in the value of sensation on a change in the value of brightness.

This is how the Weber-Fechner law (k~100) looks like.

This formula is essential. In particular, it explains why it is necessary to use the values ​​of optical densities, and not the corresponding values ​​of transmission and reflection coefficients. Indeed, if you build a brightness scale, the optical densities of which make up a uniform series, then it will be perceived as a uniform lightness scale.

Previously, we considered the difference between two brightnesses when abstracting from their environment, implicitly assuming that the difference between them is much less than their values. When considering real images, this is not the case - we have a certain range of brightness and some average level of brightness - and our perception will change.

It was found that in a natural object with a maximum brightness of 6000 nits, a brightness interval of 2.3 (200:1) and an eye adaptation level of 1500 nits, the human eye can distinguish 100 brightness levels. These indicators correspond to the landscape at an average level of daylight illumination. In an object with a maximum brightness of 40 nits, a brightness interval of 1.6 (40:1), and an adoption level of 10 nits, the eye can distinguish about 70 brightness levels. These indicators correspond to a photographic print on paper of the above-mentioned landscape and viewed under average artificial lighting.

Methods, sensors and devices used to measure brightness and their principles of operation

A luminance meter is used to measure brightness. The luminance meter is designed to measure the brightness of sections of the working field of the screen. The dimensions of the photometered areas, depending on the shape, should be of the following sizes: round - diameter from not more than 0.1 mm to not less than 20 mm, rectangular - width not more than 0.05 mm, length - from 2.0 to 5.0 mm. Measurement limits - from not more than 1.0 to not less than 200 cd/m 2 (main range) with the extension of the upper measurement limit due to a calibrated light attenuator. The main measurement error should be no more than 10%. The error in correcting the relative spectral sensitivity of the photodetector for the relative spectral luminous efficiency of monochromatic radiation for daytime vision is no more than 10%.

On a plane perpendicular to the observation axis.

B (α) = d I (α) d σ cos ⁡ α (\displaystyle B(\alpha)=(\frac (dI(\alpha))(d\sigma \cos \alpha )))

In the definition given above, it is understood, if considered as a general, that the source has a small size, more precisely a small angular size. In the case when we are talking about a significantly extended luminous surface, each of its elements is considered as a separate source. In the general case, therefore, the brightness of different points on the surface can be different. And then, if we talk about the brightness of the source as a whole, generally speaking, the average value is meant. The source may not have a specific radiating surface (a luminous gas, a region of a medium that scatters light, a source of complex structure - for example, a nebula in astronomy, when we are interested in its brightness as a whole), then under the surface of the source we can mean a conditionally chosen surface limiting it or simply remove the word "surface" from the definition. [ ]

1 asb \u003d 1 / π × 10 -4 sb \u003d 0.3199 nt \u003d 10 -4 Lb.

Brightness L - light quantity, equal to the ratio of the luminous flux d 2 Φ (\displaystyle d^(2)\Phi ) to the geometric factor d Ω d A cos ⁡ α (\displaystyle d\Omega dA\cos \alpha ) :

L = d 2 Φ d Ω d A cos ⁡ α (\displaystyle L=(\frac (d^(2)\Phi )(d\Omega dA\cos \alpha ))).

Here dΩ (\displaystyle d\Omega ) is the solid angle filled with radiation, d A (\displaystyle dA)- the area of ​​the area emitting or receiving radiation, - the angle between the perpendicular to this area and the direction of radiation. Two practically most interesting particular definitions follow from the general definition of brightness:

Luminance emitted by the surface d S (\displaystyle dS) at an angle α (\displaystyle \alpha ) to the normal of this surface, is equal to the ratio of the luminous intensity I (\displaystyle I), radiated in a given direction, to the projection area of ​​the radiating surface on a plane perpendicular to this direction:

L = d I d S cos ⁡ α (\displaystyle L=(\frac (dI)(dS\cos \alpha )))

Brightness

Brightness - illuminance ratio E (\displaystyle E) at a point in the plane perpendicular to the direction to the source, to the elementary solid angle in which the flow that creates this illumination is enclosed:

L = d E d Ω cos ⁡ α (\displaystyle L=(\frac (dE)(d\Omega \cos \alpha )))

Brightness is measured in cd/m2. Of all light quantities, brightness is most directly related to visual sensations, since the illumination of the images of objects on the retina is proportional to the brightness of these objects. In the system of energy photometric quantities, a value similar to brightness is called energy brightness and is measured in W / (sr m 2).

In astronomy

In astronomy, brightness is a characteristic of the emissivity or reflectivity of the surface of celestial bodies. The brightness of weak celestial sources is expressed by the magnitude of an area of ​​1 square second, 1 square minute or 1 square degree, that is, the illumination from this area is compared with the illumination given by a star with a known magnitude.

Thus, the brightness of the moonless night sky in clear weather, equal to 2⋅10 −4 cd/m², is characterized by a magnitude of 22.4 s 1 square second or a stellar magnitude of 4.61 s 1 square degree. The brightness of the average nebula is 19-20 magnitudes from 1 square second. The brightness of Venus is about 3 magnitudes from 1 square second. The brightness of the area in 1 square second, over which the light of a star of zero magnitude is distributed, is equal to 92,500 cd / m². A surface whose brightness does not depend on the angle of inclination of the site to the line of sight is called orthotropic; the flux emitted by such a surface per unit area obeys Lambert's law and is called lightness; its unit is the lambert, corresponding to a total flux of 1 lm (lumen) from 1 m².

Examples

see also

Notes

1. A light source can be understood as a surface emitting, as well as reflecting or scattering light. It can also be a 3D object.
2. In the case when the source is not a luminous surface, we are talking about a projection of a three-dimensional body or a region of space, which is considered a source.

Luxmeter - a device for measuring illumination, brightness and pulsations. It is necessary to determine the quality characteristics of light. Dim lighting and high pulsation factor cause eye strain, which negatively affects the general condition of the body: fatigue, inexplicable depression, and other unpleasant sensations appear. The main element of the light meter is the photo sensor. The rays of light falling on it transfer their energy to electrons, as a result of which a current of a certain strength arises, characterizing the degree of brightness or illumination.

From this article you will learn how to use a light meter, why you need to take measurements and what measures you need to take so that the lighting of your workplace, apartment, country house, cottage and other places of stay meets sanitary standards. We will consider the measurement of ripple, illumination and brightness - the conditions under which it is necessary to determine these parameters, as well as their effect on the human body.

Ripple measurement

The pulsation coefficient of the light flux is an indicator that characterizes the unevenness of the light flux. Distinguish between pulsation of illumination and pulsation of brightness. Both characteristics are measured as a percentage. Permissible levels of the pulsation coefficient are regulated by the updated version of SP 52.13330.2011 "Natural and artificial lighting. Updated version of SNiP 23-05-95" and SanPiN 2.2.1 / 2.1.1.1278-03. As a result of medical research, scientists have found that the human eye perceives pulsations with a frequency of up to 300 Hz - they affect the brain, resulting in suppression of the natural biorhythms of the central nervous system, hormonal disturbances, and other deviations in the activity of vital body systems.

It is necessary to measure the ripple for all lighting fixtures and devices equipped with displays: laptops, tablets, smartphones and mobile phones as well as table and ceiling lamps and other light sources. To measure the pulsation coefficient of illumination, it is necessary:

• put the luxmeter-pulsemeter on a work or school table, on the floor or any other surface, while the light flux should fall on the photo sensor;
• if used multifunction device, for example, RADEX LUPIN, then it is enough to switch to the heart rate monitor mode - press the "P" button;
• read the result from the display.

To measure the pulsations of monitors, screens, LED and other lamps, you must:

• bring the luxmeter-pulsemeter as close as possible to the measurement object, while the photo sensor should be directed towards the object being measured;
• if a multifunctional device is used, for example, RADEX LUPIN, then it is enough to turn the photo sensor towards the measurement object and switch the light meter to the pulse meter mode - press the "P" button;
• read the result from the display.

The following factors can affect the reliability of measurement results:

• the presence of additional light sources;
• movement of the heart rate monitor during measurements - the device must remain motionless;
• other obstacles - objects and people moving nearby, including falling leaves, flying birds and insects, etc.

Important! For accurate ripple measurements of fluorescent, LED and discharge lamps it is necessary to wait 5 minutes until they reach a stable mode of operation. It is much more convenient to work with the RADEX LUPIN heart rate monitor, as it is equipped with a rotary photocell.

In accordance with SanPiN 2.2.1 / 2.1.1.1278-03, the maximum permissible value pulsations for workshops, bathrooms and waiting areas is 20%, for offices - 15%, living rooms and bedrooms - 10% each, children's, workplaces of PC operators, offices and libraries - 5%. It is important to remember that we are not always able to see how the lamp flickers, but the excess acceptable level pulsation coefficient has a negative effect on the state of the nervous system, and on working capacity, and on mood.

Light measurement

Illumination is a physical quantity, which is the ratio of the luminous flux incident on a unit area, does not depend on direction. The unit of measure is Lux (lm/m2). Measuring illumination with a luxmeter allows you to check the working and living conditions, create suitable conditions for plants and animals, determine the characteristics of video equipment:

• the luxmeter must be placed horizontally at the measurement point; if it is necessary to determine the illumination of the workplace, the device must be placed on the table so that the photocell is directed towards the source or sources of light;
• when using the RADEX LUPIN light meter, you need to switch to the illumination measurement mode - press the "E" button;
• read the result from the display.

The light meter determines the amount of light falling on the surface from all sources, so if you need to know the parameters of a particular lighting fixture, all others must be turned off.

In accordance with SANPIN 2.2.1 / 2.1.1.1278-03, the minimum illumination of desks (hobby tables), rooms for engineers is 500 Lx, rooms for group classes for preschoolers, surfaces computer tables and in reading rooms - 400 Lx, offices, libraries and locksmith workshops - 300 Lx.

Poor lighting contributes to the development of myopia and other vision problems, causes fatigue, and negatively affects work productivity. Particular attention should be paid to the lighting of educational places, since while reading, writing or working on a computer, with a lack of light, the eyes are greatly overstrained. To measure the illumination, you do not need to invite professionals, it is enough to acquire luxmeter RADEX LUPIN. It is not expensive, like an ordinary household light meter, but in terms of measurement accuracy it is not inferior to professional measuring equipment.

Brightness measurement

Brightness - the intensity of light emitted by the surface of a light source, measured in candela per m 2 . Depends on the reflectivity of the coating. So, with the same illumination, the brightness may differ. Lights and screens that are too bright or too bright can cause discomfort. As a result, the ability to concentrate decreases, labor productivity decreases.

They mainly measure the brightness of monitors, screens and displays. It is more difficult to determine this parameter for lighting fixtures - due to the curvilinearity of the surface, it is difficult to obtain a reliable result, in addition, high brightness does not guarantee sufficient illumination. The measurement of this parameter with a RADEX LUPIN household luminance meter is carried out by an overhead method:

• switch to the brightness measurement mode - in RADEX LUPIN, press the "L" button;
• display White background;
• install the photocell as close as possible to the measured monitor, display or lamp, if the lighting device heats up, keep it at a distance of 1 cm from the surface;
• count the result.

When taking measurements, the instrument must be kept still. In order to increase the reliability of the result, it is necessary to determine the brightness at several points of the lamp or screen, and then calculate the average value. When working on a PC, it is recommended that there are no light sources with a brightness of more than 200 cd / m2 in the field of view.

RadexLight software for RADEX LUPIN light meter

Analysis of lighting parameters is much more convenient to carry out using a free software RadexLight. To do this, you need to download RadexLight - the software is distributed free of charge. The program can be downloaded from the luxmeter description page.

Program functions:

• obtaining information about luminous flux;
• construction frequency spectrum pulsations;
• output of measurement parameters;
• determination of the pulsation coefficient;
• filter off 300 Hz - given function It is provided only in the program, it is absent on the device.

Information is displayed on the monitor in the form of graphs, which allows you to get a complete picture of the amplitude, frequency and shape of the light flux.

How to improve the quality of lighting?

Most often, deviations in the operation of lighting devices are caused by their poor quality. High ripple is typical for inexpensive fluorescent lamps with electromagnetic start control. In devices with electronic ballasts, the ripple level is lower. The best way reduce the pulsation level - replace the lamps or the lamp. To measure flicker led lamp and check the quality of LED and other lamps, or rather their characteristics upon purchase, can be compact luxmeter RADEX LUPIN, which provides high measurement accuracy.

To reduce the ripple of displays and screens, you will have to experiment with the settings. For example, increase the brightness until the level of pulsations becomes normal. At the same time, you can adjust the color palette in such a way that when looking at the screen there is no discomfort. To increase the illumination, you can replace the lamps or, in addition to the main light source, use auxiliary ones: desk lamp or bra.

How to measure LAMP parameters

In accordance with GOST R 54944-2012, it is necessary to use devices with a maximum error of 10% to measure illumination. As a rule, this requirement is met by expensive luxmeters, the cost of which is so high that they are not purchased to measure light parameters in a domestic environment. So it was until recently, until the light meter appeared RADEX LUPIN, with which you can determine the illumination, ripple and brightness. The measurement error is 10%.