50 professional lighting vocabulary in the lighting industry

When it comes to professional lighting vocabulary, most people hang on the words of illuminance, brightness, color temperature, etc. However, as a professional lighting person, there are many special vocabulary, here are 50 common ones for the lighting industry. Vocabulary and notes.


1, color rendering (Color Rendering Index)

The degree to which a light source is rendered for an object's color is called color rendering and is often referred to as the color rendering index (Ra). The degree to which a light source appears to the color of an object is called color rendering, which is the degree of fidelity of the object. Color rendering is a very important indicator of luminaire performance.

2, illumination (Luminosity)

The degree to which an object is illuminated is called illuminance and is expressed by the luminous flux received per unit area.

The unit is (lux), which is lm/m2. 1 lux is equal to 1 lumen of light flux and illuminance distributed over the lm2 area,

The illuminance is based on the luminous flux acceptable to the vertical plane.

3. Luminous Intensity

The luminous intensity of the illuminant in a given direction is the quotient obtained by dividing the luminous flux dΦ transmitted in the solid angle element dΩ of the illuminating body by the solid angle element, that is, the luminous flux per unit solid angle. The unit is Candela (cd), lcd = 1 lm / sr.

4, light effect (Lumen)

The ability of an electric light source to convert electrical energy into light, expressed as the luminous flux emitted divided by the amount of electricity consumed.

Unit per watt lumen (lm/W)

5, Luminous Flux

The unit of luminous flux, the point source of luminous intensity of 1 candela (cd), in unit solid angle (1 steradian)

The luminous flux emitted inside is "1 lumen", abbreviation lm

6, protection level (Ingerss Protection)

The degree of protection consists of two numbers.

The first number indicates dustproofness and the level of foreign matter intrusion prevention. The second number indicates moisture resistance and water resistance.

The degree of airtightness, the larger the number, the higher the degree of protection.

7, distribution curve (Distribution Cruve Flux)

The distribution of light emitted by a luminaire or light source in space. Mainly records the luminous flux of the luminaire and the number of light sources.

Power, power factor, lamp size, lamp efficiency, etc.

8, glare (Galre)

There is a very bright object or a strong contrast of brightness in the field of view, and the visual discomfort caused by it is called glare.

Glare is an important factor affecting the quality of lighting.

9, Average Illuminance (Average Illuminance)

That is, the illumination of the light source indicates the average value of the illumination at each point.

10. Maintaining Average Illuminance

The average illuminance on the specified surface shall not be lower than this value, which is the average illuminance on the specified surface at the moment the illuminating device must be maintained.

11, visual tasks (Visual Task)

In the work and activities, the observation process of the details and targets presented in front of the background. Visual work is divided into primary visual work and secondary visual work, depending on the area in which the vision stays.

12. Reference Place Refers to the plane that measures or specifies the illuminance.

13. Working Plance A plane that works on its surface.

14, general lighting (General Lighting)

Also known as "background lighting" or "environmental lighting" is the basis of a lighting plan that refers to non-directional lighting that fills the room, creating a generally adequate lighting base for all activities in the space room.

15. Localized General Lighting

An evolutionary version of general illumination, designed to illuminate the general illumination of a particular area, such as the place where it is being worked, with different illuminations.

16, local lighting (Local Lighting)
In order to meet the special needs of certain parts of the room, the lighting mode of the lighting fixtures is set within a certain range.

Generally, the lighting fixture is installed close to the working surface, and is often used in the following occasions: local illumination is required for higher illumination, and general illumination is not irradiated to some extent due to shielding, and it is necessary to reduce the reflection glare in the working area, so as to strengthen Illumination in a certain direction to enhance the sense of material in the building.

17, Mixed Lighting (Mixed Lighting)

Illumination consisting of general lighting and local lighting for more flexible lighting effects.

18, Acent Lighting

In order to increase the illumination of a specified area or target, it is more prominent than the surrounding area. Often used to emphasize specific parts or furnishings of space, such as architectural elements, frames, wardrobes, collectibles, decorations and artwork, museum artifacts, etc.

19, Emergency Lighting (Emergency Lighting)

Illumination enabled due to power failure of normal lighting, including evacuation lighting, safety lighting, and standby lighting. The most common in life is the application lights and safe evacuation lights that can be found everywhere in the corridor.

20, safety lighting (Safety Lighitng)

Emergency lighting to ensure the safety of personnel at risk.

21, Stand-by Lighting (Stand-by Lighting)

Emergency lighting to ensure that normal activities continue or temporarily continue, such as emergency lights for the brightness of the stairs when the stairway is guaranteed to be powered off)

22, stroboscopic (Stroboscopic)

Under the illumination of light with a certain frequency, it is observed that the motion of the object exhibits a phenomenon different from its actual motion.

23. Uniformity Ratio Of Illuminance

Specifies the ratio of the minimum illuminance to the average illuminance on the surface, the symbol is U0.

24, Shielding Angle Of Luminaire

The angle between the plane of the light exit port and the line of sight where the spot is not visible.

25, color temperature (Color Temperature)

When the chromaticity of the light source is exactly the same as the chromaticity of the black body at a certain temperature, the absolute temperature of the black body is the temperature of the light source, which is called "color temperature", and the unit is (K).

26, Chromaticity Tolerances

Deviation of the light source and the nominal color of the light source in a batch of light sources is represented by the color matching standard deviation SDCM.

27. Luminous Flux Maintenance The ratio of the luminous flux of a Luminous Flux Maintenance lamp to its initial luminous flux after a given ignition time, usually expressed as a percentage.

28, reflectance (Reflectance)

The ratio of the reflected radiant flux or luminous flux to the incident radiant flux or luminous flux given the spectral composition, polarization state, and geometric distribution of the incoming radiation.

29. Lighting Power Density (LPD)

The installation power of general lighting per unit area (including auxiliary electric devices such as light sources, ballasts or transformers) is watts per square meter.

30, Room Index (Room Index)

A value indicating the geometry of a room or place, the value of which is 2 times the room or site area and the difference between the perimeter of the room or site and the difference between the height of the fixture and the height of the face.

31. Annual Expo Exposure

The value of the cumulative illuminance of the object is measured by the product of the illuminance received by the object and the accumulated hour of the year, in units of annual lux hours (lx·h/a).

32, Light Wane

LED light decay means that after a period of illumination of the LED, its light intensity will be lower than the original light intensity, and the low part is the light decay of the LED. The general LED package manufacturer does the test under laboratory conditions. (At normal temperature of 25 ° C), the LED is continuously lit with a direct current of 20MA for 1000 hours to compare the light intensity before and after lighting.

33, bulb size (Bulb Dimension)


The shape of the bulb and its dimensions (the maximum diameter of the bulb, expressed in one-eighth of an inch). For small fluorescent products, "S", "D", "T", and "Q" represent single, double, triple, and quadruple Biax sizes. The code also includes a reference, for example T4 indicates the size of the tube. The rectangular illuminator is named "Rect" and the number of millimeters in the horizontal direction.

34, Light Angle (Lighting Angle)


Refers to the angle of the light of the lamp, the angle of the lamp cup is generally 10 °, 24 °, 38 °. The larger the beam angle of the lamp cup of the same power is, the smaller the center light intensity is, and the wider the light spot is, the softer the light beam is. The smaller the beam angle is, the larger the center light intensity is, and the narrower and harder the light spot is.

35, wavelength (Wave Length)

The distance between two stores of the same phase at the same time in the direction of the periodic wave propagation.

36. Electromagnetic interference (EMI)

Electrical interference caused by electrical or electronic equipment. The interference level of high-frequency electronic equipment shall be subject to the provisions of the Federal Communications Commission (FCC) or the International Electrotechnical Commission (IEC).

37, reflector (Reflector)

A device that uses a reflection phenomenon to change the spatial distribution of light flux of a light source.

38, Eaves Lighting


The light source is attached to the ceiling and is illuminated by a panel that is parallel to the wall. The light is distributed on the vertical wall.

39. Spectral Distribution


Refers to the spectral distribution of light metrics (light flux, light intensity, etc.) or radiation metrics (radiation efficiency, radiation intensity, etc.) as a function of wavelength.

40, Spectral Lighting Distribution

For radiation, the relative spectral distribution of a certain photometric quantity (light flux, light intensity, etc.) is used to describe the spectral characteristics of the radiation.

41. Spectral Luminance Efficiency Curve

This curve gives the relative sensitivity (V) of the CIE standard photometric observer to the monochromatic radiation determined by the wavelength.

42. Light Output Ratio

The ratio of the total luminous flux emitted by the luminaire to the total luminous flux emitted by the source without the luminaire under specified actual measurement conditions.

43. Indirect lighting (Indirect Lighitng)

Lighting with a luminaire with a certain light distribution curve, the light intensity directly reaching the working surface does not exceed 10% of the total luminous flux without considering the boundary of the working surface.

44. Radio Frequency Interference (RFT)

An electromagnetic interference that can radiate in the air.

45, input voltage (Input Voltage)


Input from the power supply or power line to the voltage including the ballast.

46, dimmer (dimmer)

A device that is installed in the circuit to change the light source output of the light source in the illumination system.

47, maintenance factor (Maintenance Index)

The maintenance factor K is defined as the ratio of the average illuminance (ie, maintaining illuminance) produced by the illumination system on the work surface to the average illuminance (ie, the initial illuminance) when the system is newly installed.

48. Economic lifespan (Economic Lifespan)


The integrated beam output is reduced to a specific proportion of hours while considering both lamp damage and beam output attenuation.

49, Glare Angle (Glare Angle)

The angle between the line connecting the farthest luminaire and the glare evaluation point in the room and the sag of the luminaire is called the γ angle, and the range of the γ angle is greater than or equal to 45°, which is called the glare angle.

50, High Mast Lighting (Light Mast Lighting)

A method in which a group of lamps is mounted on a pole with a height greater than 20 m (including 20 m) for large-area illumination.


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