Professional lighting engineers and specialists working in the field of lighting constantly use different terms and definitions that mean little to the average person.

To make it easier to understand what we are talking about and what these words mean, we have prepared a list that explains the main lighting terms and characteristics. You don’t need to learn it by heart; you can simply go to the desired page and refresh your memory of a forgotten parameter. Speaking “the same language” is always easier.

Lighting parameters and concepts.

1 - Visible and optical radiation

The entire world around us is formed by visible radiation, concentrated in the band of electromagnetic waves from 380 to 760 nm. On one side is added to it ultraviolet radiation(UV), and on the other, infrared (IR).

UV rays have biological effects and are used to kill bacteria. They are used in doses for therapeutic and health-improving effects.

IR rays are used for heating and drying in installations, as they mainly produce a thermal effect.

2 - Luminous flux (F)

Luminous flux characterizes the power of visible radiation in terms of its effect on human vision. Measured in lumens(lm). The magnitude does not depend on the direction. Luminous flux is the most important characteristic.

For example, an E27 75 W incandescent lamp has a luminous flux of 935 lm, a halogen G9 lamp of 75 W - 1100 lm, a fluorescent T5 lamp of 35 W - 3300 lm, a metal halide G12 of 70 W (warm) - 5300 lm, LED E27 9.5 W ( warm) - 800 lm.

3 - Lumen

Lumen (lm) is the luminous flux from a light source (lamp) at an ambient temperature of 25°, measured under reference conditions.

4 - Illumination (E)

Illumination is the ratio of the luminous flux supplied to a surface element to the area of this element. E=F/A, where A is the area. Illuminance unit - luxury(OK).

Most often, horizontal illumination is normalized (on a horizontal plane).

Medium light ranges: outdoors at artificial lighting from 0 to 20 lux, indoors from 20 to 5000 lux, 0.2 lux on a full moon natural conditions, 5000 -10000 lux during the day when it is cloudy and up to 100,000 lux on a clear day.

The picture shows: a - average illumination in area A, b - general formula for calculating illumination.

5 - Light intensity (I)

Luminous intensity is the spatial density of the luminous flux limited by the solid angle. That is, the ratio of the luminous flux emanating from a light source and propagating within a small solid angle containing the direction in question.

I=Ф/ω The unit of measurement of luminous intensity is candela (cd).

The average luminous intensity of a 100 W incandescent lamp is about 100 cd.

KSS ( luminous intensity curve) - distribution of light intensity in space, this is one of the most important characteristics of lighting devices, necessary for calculating lighting.

6 - Brightness (L)

Brightness (light density) is the ratio of the luminous flux carried in an elementary beam of rays and propagating in the solid angle to the cross-sectional area of this beam.

L=I/A (L=I/Cosα) The brightness unit is cd/m2.

Brightness is related to the level of visual sensation; the spread of brightness in the field of view (in the room/interior) characterizes the quality (visual comfort) of lighting.

In complete darkness, a person reacts to a brightness of one millionth of a cd/m2.

A fully luminous ceiling with a brightness of more than 500 cd/m2 causes discomfort in a person.

The brightness of the sun is approximately a billion cd/m2, and the brightness of a fluorescent lamp is 5000–11000 cd/m2.

7 - Luminous efficiency (H)

The luminous efficiency of a light source is the ratio of the luminous flux of a lamp to its power.

Η=F/R The unit of measurement of light output is lm/W.

This is a characteristic of the energy efficiency of a light source. Lamps with high luminous efficiency provide energy savings. By replacing an incandescent lamp with a light output of 7–22 lm/W with fluorescent lamps (50–90 lm/W), energy consumption will decrease by 5–6 times, and the illumination level will remain the same.

8 - Color temperature (TC)

Color temperature determines the color of light sources and the color tone of the illuminated space. The color temperature is equal to the temperature of a heated body (Planck emitter, black body) that is the same color as a given light source.

The unit of measurement is Kelvin (K) on the Kelvin scale: T - (degrees Celsius + 273) K.

Candle flame - 1900 K

Incandescent lamp - 2500–3000 K

Fluorescent lamps - 2700 - 6500 K

Sun - 5000–6000 K

Cloudy sky - 6000–7000 K

Clear day - 10,000 - 20,000 K.

The color rendering index characterizes the degree of color reproduction various materials when they are illuminated by a light source (lamp) and compared with a reference source.

The maximum color rendering index value is Ra =100.

Color rendering indicators:

Ra = 90 or more - very good (color rendering degree 1A)

Ra = 80–89 - very good (color rendering degree 1B)

Ra = 70–79 - good (color rendering degree 2A)

Ra = 60–69 - satisfactory (color rendering degree 2B)

Ra = 40–59 - sufficient (color rendering degree 3)

Ra = less than 39 - low (color rendering degree 3)

Ra aka CRI- color rendering index was developed to compare light sources of the continuous spectrum whose color rendering index was above 90, since below 90 it is possible to have two light sources with the same color rendering index, but with very different color rendering.

Comfortable CRI value for the human eye = 80–100 Ra

Below are the basic concepts and relationships of light indicators.

Lighting is one of the most important conditions for normal life. Properly arranged lighting provides good visibility and creates favorable conditions labor. Unsatisfactory lighting causes premature fatigue, dulls the worker's attention, reduces labor productivity, degrades quality indicators and can cause an accident. Poor lighting over a long period of time can also lead to poor vision.

There are three types of industrial lighting: natural, artificial and combined.

natural illumination of premises with sky light (direct or diffuse) penetrating through light openings in the external structures of buildings;

artificial lighting with electric light sources;

combined lighting, in which natural light, which is insufficient by standards, is supplemented with artificial light.

Visible radiation (light) is radiation that hits the retina of the eye and can cause a visual sensation. Light part electromagnetic radiation with a wavelength from 0.38 to 0.78 microns.

Lighting technical values that determine the indicators of industrial lighting are based on an assessment of their perception by the human eye. There are quantitative and qualitative indicators of lighting.

1.1. Quantitative indicators

Towards quantitative indicators include: luminous flux, luminous intensity, illumination, brightness, reflectance.

Luminous flux (F)- the power of the luminous flux, estimated by visual sensation by the human eye. The dimension of the luminous flux is lumen (lm).

Light intensity (J)- spatial density of the light flux in a given direction, i.e. luminous flux per solid angle ω , in which it is emitted

Candela (cd),

Where ω solid angle in steradians (sr).

Illuminance (E)- the density of the luminous flux on the surface illuminated by it, the luminous flux related to the area of the illuminated surface S, measured in m 2, provided it uniform distribution along the surface when the source light falls on it perpendicularly

Brightness (V)- is a light quantity directly perceived by the eye. It is determined by the ratio of the luminous intensity in a given direction to the area of projection of the emitting surface onto a plane perpendicular to the direction of radiation

Values of maximum brightness values on the working surface.

Surface reflectance r characterizes its ability to reflect the light flux incident on it. It is determined by the ratio of the reflected light flux to the incident one

Values of the coefficient (r) for surfaces of various types.

1.2. Qualitative indicators

Toward quality indicators lighting include: background, contrast of the object of discrimination with the background, glare indicator, illumination pulsation coefficient, discomfort indicator.

Background- a surface adjacent directly to the object of discrimination on which it is viewed. The background is considered light if the reflectance P is greater than 0.4; medium at P = 0.2...0.4 and dark if P is less than 0.2.

Contrast of the object of discrimination with background K photometrically measured difference in brightness of two zones. It is determined by the ratio of the absolute value of the difference between the brightness of the object and the background to the brightness of the background:

Contrast is considered high when K is more than 0.5 (the object and the background differ sharply in brightness), average when K = 0.2...0.5 (noticeably different) and small if K is less than 0.2 (differ little).

Blindness index 2 (P)- criterion for assessing the glare of a lighting installation, determined by the expression

P = (S - 1) 1000,

where S is the glare coefficient, equal to the ratio of the threshold brightness differences in the presence and absence of blinding sources in the field of view.

Normalized values of the coefficient R.

Illumination pulsation coefficient (Kp)- a criterion for assessing the relative depth of illumination fluctuations as a result of changes in time of the luminous flux of gas-discharge lamps when powering them alternating current, expressed by the formula

where Emax, Emin, and Eсr are, respectively, the maximum, minimum and average values of illumination over the period of its fluctuation, lux.

Normalized values of Kp.

Discomfort index (M)- criterion for assessing uncomfortable brightness 1, causing unpleasant sensations when the brightness is unevenly distributed in the field of view. It determines the degree of additional visual tension caused by the presence of a sharp difference in brightness in a lit room.

This indicator for production premises is not standardized, its normalized values for residential, public and administrative premises, there is a formula for determining the discomfort index M.

Of the listed lighting indicators, the following are directly measured (names of devices are indicated in brackets):

Illumination (lux meters);

Brightness (subjective and objective photometers).

Using these instruments, it is possible to determine the values of the reflection coefficients P and pulsation Kp of the contrast of the object of discrimination with the background K and the blindness index P.

Illumination standards When choosing the type of lamps, their quantity and power, it is necessary to take into account the illumination standards. The standards give three values for the degree of illumination: low, normal and high. Usually the normal level is used, but in some cases choosing a low or high level of illumination is advisable.
Degree of protection of electrical equipment The degree of protection is indicated by the combination IP XX. The first number is the degree of protection against dust and fur. influences. The second is the degree of protection against moisture. As street lamps at a height of up to 0.5 m, lamps with protection class IP 44 can be used. For installation on high masts (above human reach), the minimum protection class is IP 23. Luminaires mounted at ground level must be waterproof (IP 67), and luminaires immersed in water (for example, to illuminate a pond) must have a protection class of IP 68 (protection against the ingress of water under pressure).
Protection class 0 class - there is no complete double and reinforced insulation, there is no possibility of grounding. Class I - there is complete insulation, and there is the possibility of grounding. Class II - equipped with double and reinforced insulation, without the possibility of grounding. Class III - a luminaire intended for connection only to a protective voltage network.
Units of measurement Here are some physical quantities that characterize a light source. They can be used when choosing lamps and their location. Light intensity (I). The unit of measurement is candela (cd).

Illumination (E) - luminous flux per unit of illuminated surface. The unit of measurement is lux (lx). 1 lx = 1cd*sr/m2, where sr is the solid angle (in steradians). Brightness (L) characterizes the glow of a light source in a given direction.

The brightness of an element of a luminous surface in any direction is determined by the ratio of the luminous intensity of this element to the area of the element's projection onto a plane perpendicular to this direction.

Color temperature (T). It is measured in degrees Kelvin (K). Characterizes the spectral composition of radiation.

Illumination: Moonlight 0.25 lx Sun through clouds 10,000 lx Sunlight 100,000 lx Office lighting 300-2000 lx Road lighting 10-50 lx

Brightness: Fluorescent lamp 0.8 cd/m2 Well-lit street 2 cd/m2 Midday sun 150,000 cd/m2 The light intensity of a candle is about 1 cd, and the light of a lighthouse can reach 2,000,000 cd.

Measuring lighting parameters. The main parameter used in assessing lighting is illuminance e, measured in lux.

Luxmeters of various types are used to measure illumination.

An example of an analog lux meter is the Yu-116 device, the operating principle of which is based on the phenomenon of the photoelectric effect.

Under the influence of the light flux incident on the selenium photocell, a current arises in a closed circuit, the magnitude of which is proportional to luminous flux. The device is calibrated in lux. A significant advantage of the selenium photocell compared to other types of photocells is that its spectral sensitivity curve most closely matches the relative visibility curve of the human eye. When measuring illumination, the photocell is installed in the working plane (horizontal or vertical) at a certain distance from the operator carrying out the measurements so that the shadow does not fall on the photocell.

Currently, analogue-digital devices are widely used, making it possible to measure not only illumination, but also other parameters characterizing lighting, for example, pulsation coefficient or brightness.

An example of an analogue-digital device is the Argus-07 pulse meter-luxmeter, which is used to measure illumination and pulsation coefficient. The principle of the device is based on the conversion of the luminous flux created by extended objects into a continuous electrical signal, proportional to illumination, which is then converted by an analog-to-digital converter into a digital code displayed on the digital display of the indicator block. The measuring head contains a primary radiation converter - a semiconductor silicon photodiode with a system of light filters that form a spectral sensitivity corresponding to the visibility curve. The readings of the pulsation coefficient are indicated as a percentage, while the device determines the maximum, minimum and average value of the illumination of the pulsating radiation and calculates the value of the pulsation coefficient using the above formula.

Luminous flux
Characterizes the power of visible radiation by its effect on the human eye in special units - lumens [Lm]. Luminous flux is the most important characteristic of lamps. A regular 100 W incandescent lamp has a luminous flux of 1300 Lm, and a 70 W metal halide lamp has a luminous flux of 6000 Lm.

Illumination
This is the surface density of the luminous flux incident on an area of a given size. The unit of illumination is lux [Lx]. One of the most important values in lighting standards. Most often, horizontal illumination is normalized (in the horizontal plane). The range of illumination levels with artificial lighting is from 1 to 20 Lux outdoors and from 20 to 5000 Lux indoors. Under natural conditions, illumination E = 0.2 Lux on a full moon, 5000 - 10,000 Lux during the day with overcast skies and up to 100,000 Lux on a clear sunny day.

The power of light
This is the spatial density of the light flux limited by the solid angle. The unit of measurement of luminous intensity - candela [cd] - is reproduced by the standard and is included in the International System of Basic Units (SI).
The distribution of luminous intensity in space (luminous intensity curve, LIC) is one of the most important characteristics lighting fixtures, necessary for lighting calculations. The KSS of lamps is usually given in polar coordinates for a conventional lamp with a luminous flux of 1000 lm, i.e. in cd/kLm.

Brightness
For matte (diffuse or equally bright) surfaces, this value is proportional to the surface density of the light flux reflected or emitted by this surface. In a more general form, it is equal to the ratio of the light intensity in the direction of the observation point to the area of the luminous surface (projection) visible from this point. The brightness unit is cd/m2. Brightness is directly related to the level of visual sensation, and the distribution of brightness in the field of view (for example, in an interior) characterizes the quality of lighting. In complete darkness, a person reacts to a brightness of one millionth of a cd/m2. A solid luminous ceiling with a brightness of more than 500 cd/m2 has an uncomfortable effect. The brightness of the sun is about 1,000,000,000 cd/m2, and that of a fluorescent lamp is 5-11 thousand cd/m2.

Reflection [ρ] and transmittance [τ]
They are defined as the ratio of the luminous flux reflected [ρ] or transmitted [τ] by the material to the incident luminous flux. Reflectance coefficients of some finishing materials:
- white paint (0.7 - 0.8)
- light wallpaper (0.5 - 0.7)
- white marble - 0.45
- red brick - 0.3
- dark wood (0.1 - 0.25)
- asphalt - 0.07

When rooms are decorated with light (especially when the size is small relative to the height), the light levels increase very noticeably. The reflectance coefficient of the background against which the object is viewed is one of the indicators characterizing the conditions of visual work in the workplace. According to Russian standards, the background is considered light when the reflection coefficient is more than 0.4, medium - from 0.2 to 0.4, and dark - less than 0.2. As the background reflectance increases, the visibility of the object improves.

Luminous output
This main characteristic energy efficiency of lamps and it is equal to the ratio of the luminous flux of the lamp to its power. The use of lamps with high luminous efficiency is the main way to save energy in lighting installations. For example, by replacing incandescent lamps, the luminous efficiency of which is 7-22 lm/W, with compact fluorescent lamps (50-90 lm/W), you can reduce energy consumption by an average of 5-6 times without reducing the level of illumination.

Indicators of blindness and discomfort
These indicators characterize the direct glare of light sources or lamps. Based on the glare indicator, one can judge the degree of deterioration in visibility when exposed to glare light sources. For example, with a value of 100, visibility is reduced by 10%. According to Russian standards for precise production work the blindness index value should not be higher than 20. The discomfort index (M) characterizes the degree of discomfort or tension in the presence of sources of increased brightness in the field of view.

Cylindrical illuminance [Ec]
Characterizes the saturation of a room with light and is defined (in lux) as the average vertical illumination created at a given observation point. In Russia, this value is standardized in such premises as halls, front vestibules, auditoriums, exhibitions, reading rooms and trading floors, meeting and reception halls, etc. Increased light saturation is created at Ec levels of at least 100 lux.

Color and Chroma
The concept of color is defined as the property of visible radiation to cause a visual sensation of color (hue + saturation) and brightness of objects. Hue (red, orange, etc.) is characterized by the wavelength of visible radiation, and saturation is characterized by the purity of color associated with the degree of approximation to a spectrally pure color from the white point. For example, low-saturated color tones are obtained by greatly diluting the dye with white paint. The color of the same object can vary greatly depending on the spectral composition of the lighting.

Color temperature [Tz]
A very important characteristic of light sources that determines the color of the lamps and the color tone (warm, neutral or cold) of the space illuminated by these lamps. It is approximately equal to the temperature of a heated body of the same color as a given light source. Expressed on the Kelvin temperature scale: T = (degrees Celsius +273) K.
TC values of some sources:
- candle flame - 1900 K;
- incandescent lamps - 2500-3000 K;
- fluorescent lamps - 2700-6500 K;
- Sun - 5000-6000 K;
- cloudy sky - 6000-7000 K;
- clear sky - 10000-20000 K;

Color rendering index
One of the main color characteristics of the quality of discharge lamps. Characterizes the degree of color reproduction of various materials when illuminated by a lamp when compared with a reference light source. The highest value is Ra=100. Sodium lamps with the worst color rendering high pressure have Ra=25. According to German standards, very good color rendering (grade 1) corresponds to Ra = 80 or more, good (grade 2) - from 60 to 79, satisfactory (grade 3) - from 40 to 59 and insufficient (grade 4) - from 20 to 39 .

Light pulsation factor [Kp]
Characterizes the relative depth of illumination pulsation (in %) at a given point in the room when the lamps are powered from an alternating current network. Uncontrolled pulsation of illumination leads to an increased risk of injury when working with moving and, in particular, rotating objects, as well as to visual fatigue. In Russian standards, for most visual work, the Kp value is set to no more than 20.

What is light? What do they “eat” it with?

Poor lighting over a long period of time can also lead to poor vision.

There are three types of industrial lighting: natural, artificial and combined.

natural- illumination of premises with sky light (direct or diffuse), penetrating through light openings in the external structures of buildings;
artificial- lighting with electric light sources;
combined- lighting in which natural lighting, which is insufficient by standards, is supplemented with artificial lighting.

Visible radiation (light) is radiation that, when it hits the retina of the eye, can cause a visual sensation. Light is part of electromagnetic radiation with a wavelength from 0.38 to 0.78 microns.

1.1. Quantitative indicators

Towards quantitative indicators include: luminous flux, luminous intensity, illumination, brightness, reflectance.

Luminous flux (F)– the power of the luminous flux of radiation, estimated by visual sensation by the human eye. The dimension of the luminous flux is lumen (lm).

Light intensity (J)– spatial density of the light flux in a given direction, i.e. luminous flux per solid angle ω , in which it is emitted

Candela (cd),
Where ω – solid angle in steradians (sr).

Illuminance (E)– luminous flux density on the surface illuminated by it – luminous flux related to the area of the illuminated surface S, measured in m2, provided that it is evenly distributed over the surface when the light from the source falls on it perpendicularly

Brightness (V) is a light quantity directly perceived by the eye. It is determined by the ratio of the luminous intensity in a given direction to the area of projection of the emitting surface onto a plane perpendicular to the direction of radiation

The values of the maximum brightness values on the working surface are given in Table 1, page 14.

Reflectance surface r characterizes its ability to reflect the light flux incident on it. It is determined by the ratio of the reflected light flux to the incident one

The values of the coefficient (r) for surfaces of various types are given in table. 12., adj. 1.

1.2. Qualitative indicators

Toward quality indicators lighting include: background, contrast of the object of discrimination with the background, glare indicator, illumination pulsation coefficient, discomfort indicator.

Contrast of the object of discrimination with background K – photometrically measured difference in brightness of two zones. It is determined by the ratio of the absolute value of the difference between the brightness of the object and the background to the brightness of the background:

Blindness rate2 (P)– criterion for assessing the glare effect of a lighting installation, determined by the expression

P = (S – 1) 1000,

where S is the glare coefficient, equal to the ratio of the threshold brightness differences in the presence and absence of blinding sources in the field of view.

The normalized values of the coefficient P are given in the appendix. 1, table. 1.

Illumination pulsation coefficient (Kp)– a criterion for assessing the relative depth of illumination fluctuations as a result of changes in time of the luminous flux of gas-discharge lamps when powered by alternating current, expressed by the formula

where Emax, Emin, and Eсr are, respectively, the maximum, minimum and average values of illumination over the period of its fluctuation, lux.

The normalized values of Kp are given in the appendix. 1, table 1.

Discomfort index (M)– a criterion for assessing uncomfortable brightness1, which causes unpleasant sensations when the brightness is unevenly distributed in the field of view. It determines the degree of additional visual tension caused by the presence of a sharp difference in brightness in a lit room.

This indicator is not standardized for industrial premises; its standardized values for residential, public and administrative premises are given in Table. 2, pp. 7–8. There on page 25 there is a formula for determining the discomfort index M.

Of the listed lighting indicators, the following are directly measured (names of devices are indicated in brackets):

– illumination (lux meters);
– brightness (subjective and objective photometers).

Illumination standards When choosing the type of lamps, their quantity and power, it is necessary to take into account the illumination standards. The standards give three values for the degree of illumination: low, normal and high. Usually the normal level is used, but in some cases choosing a low or high level of illumination is advisable. Degree of protection of electrical equipment The degree of protection is indicated by the combination IP XX. The first number is the degree of protection against dust and fur. influences. The second is the degree of protection against moisture. As street lamps at a height of up to 0.5 m, lamps with protection class IP 44 can be used. For installation on high masts (above human reach), the minimum protection class is IP 23. Luminaires mounted at ground level must be waterproof (IP 67), and luminaires immersed in water (for example, to illuminate a pond) must have a protection class of IP 68 (protection against the ingress of water under pressure). Protection class 0 class - there is no complete double and reinforced insulation, there is no possibility of grounding. Class I - there is complete insulation, and there is the possibility of grounding. Class II - equipped with double and reinforced insulation, without the possibility of grounding. Class III - a luminaire intended for connection only to a protective voltage network. Units of measurement Here are some physical quantities that characterize a light source. They can be used when choosing lamps and their location. Light intensity (I). The unit of measurement is candela (cd).

Illuminance (E)- luminous flux per unit of illuminated surface. The unit of measurement is lux (lx). 1 lx = 1cd*sr/m2, where sr is the solid angle (in steradians). Brightness (L) characterizes the glow of a light source in a given direction.

Color temperature (T). It is measured in degrees Kelvin (K). Characterizes the spectral composition of radiation.

Illumination: Moonlight 0.25 lx Sun through clouds 10,000 lx Sunlight 100,000 lx Office lighting 300-2000 lx Road lighting 10-50 lx

Brightness: Fluorescent lamp 0.8 cd/m2 Well-lit street 2 cd/m2 Midday sun 150,000 cd/m2 The intensity of a candle is about 1 cd, and the light of a lighthouse can reach 2,000,000 cd.

Measuring lighting parameters. The main parameter used in assessing lighting is illuminance e, measured in lux.

Luxmeters of various types are used to measure illumination.

An example of an analog lux meter is the Yu-116 device, the operating principle of which is based on the phenomenon of the photoelectric effect.

Under the influence of the luminous flux incident on the selenium photocell, a current arises in a closed circuit, the magnitude of which is proportional to the luminous flux. The device is calibrated in lux. A significant advantage of the selenium photocell compared to other types of photocells is that its spectral sensitivity curve most closely matches the relative visibility curve of the human eye. When measuring illumination, the photocell is installed in the working plane (horizontal or vertical) at a certain distance from the operator carrying out the measurements so that the shadow does not fall on the photocell.

An example of an analogue-digital device is the Argus-07 pulse meter-luxmeter, which is used to measure illumination and pulsation coefficient. The principle of the device is based on the conversion of the luminous flux created by extended objects into a continuous electrical signal, proportional to illumination, which is then converted by an analogue - digital converter into a digital code displayed on the digital display of the indicator block. The measuring head contains a primary radiation converter - a semiconductor silicon photodiode with a system of light filters that form a spectral sensitivity corresponding to the visibility curve. The readings of the pulsation coefficient are indicated as a percentage, while the device determines the maximum, minimum and average value of the illumination of the pulsating radiation and calculates the value of the pulsation coefficient using the above formula.

Types of lighting

PRODUCTION LIGHTING

Topic 5

Plan:

Basic parameters characterizing light

Basic lighting requirements

A properly executed lighting system plays a significant role in reducing occupational injuries, reducing the potential hazards of many production factors, creating normal working conditions, and increasing overall performance. Lighting is characterized high quality And quantitative indicators. Quantitative are: luminous flux, luminous intensity, illumination, brightness, reflection coefficient. Qualitative indicators are: background, contrast of object with background, blindness, degree of discomfort, light ripple factor.

Luminous flux (F)- this is the part of the radiant flux that is perceived by vision as light. The unit of measurement for luminous flux is lumen(lm).

The power of light(I) is a quantity that evaluates the spatial density of the light flux and represents the ratio of the light flux dФ to the solid angle dω within which the light flux propagates:

The unit of measurement for luminous intensity is candela(KD).

Illumination ( E) is the surface density of the luminous flux, and is the ratio of the luminous flux dФ incident on a surface element dS to the area of this element.

The unit of illumination measurement is luxury(OK).

Surface brightness(L) is the ratio of the intensity of light emitted in the direction in question to the area of the luminous surface.

Surface brightness is measured in CD/m2

Reflectance coefficients (ρ) is the ratio of the luminous flux reflected from the surface F neg to the light flux incident on it F pad.

Background- this is the surface adjacent directly to the object of discrimination on which it is viewed. The background is considered: light when ρ > 0.4, medium when ρ = 0.2-0.4, dark when ρ< 0,2.

Contrast of object with background (K) is the ratio of the brightness of the object in question and the background.

K - contrast of the object with the background

L 0 , L Ф – brightness of the object and background.

When K > 0.5 - high contrast, K = 0.2 ... 0.5 - medium, K< 0,2 – малый.

Blindness rate (P) is a criterion for assessing the glare of a lighting installation:

Glare factor (S) represents the ratio of the visibility of the object of observation when shielding brilliant sources (V 1) of light and without shielding (V 2), respectively:

Discomfort index (M) is a criterion for assessing discomfort brightness, causing unpleasant sensations when the brightness is unevenly distributed in the field of view.

Illumination pulsation coefficient (KP)– is a criterion for assessing the relative depth of illumination fluctuations as a result of changes in light flux over time.

E max, E min - illumination values for the period.

E av - average illumination value for the period.

Numerous studies have established the great influence of illumination of work surfaces on labor productivity. Moreover, an increase in illumination helps to improve performance even in cases where the labor process does not depend on visual perception. In poor lighting, a person quickly gets tired, does not work well, and the potential danger of erroneous actions and accidents increases. Ultimately, poor lighting can lead to occupational diseases, such as work myopia (myopia).