List of other terms of illumination (H-N)
Source: Date:2017-03-28



Environmental factor (Road)

The average illuminance average illuminance of certain width on the sidewalk and driveway width ratio.


High intensity discharge discharge formed by the current flowing through the space between two electrodes.

Arc discharge (gas or vapor)

Compared with the glow discharge, the cathode drop is relatively low.

Mixed light

The bulb shell is internally provided with a high-pressure mercury vapor discharge tube and an incandescent filament, and a light source which is connected in series, such as a ML lamp. The bubble shell can be a diffusion type or coated with fluorescent material.

Hybrid reflection

Regular reflection and diffuse reflection.

Hybrid transmission

Mixing of regular and diffuse transmission.

Infrared radiation

Optical radiation with wavelengths greater than visible radiation.

Glow discharge

The two emission of the cathode is much stronger than that of the emission of the ion.

Blackbody locus (Planck locus)

Chromaticity diagram representing different blackbody temperature (Planck radiator) color curve.

(Planck blackbody radiator)

Heat radiator for all incident light with different wavelength and incident direction or polarization are completely absorbed.



Staggered lamp

Road lighting cloth mode, when the lamps are placed alternately on both sides of the driveway.

Uniform chromaticity scale (UCS)

Two-dimensional coordinates. The coordinate definition makes the coordinate distance on the whole chromaticity diagram as equal as the color difference of the same brightness.

Local lighting

Illuminate the specified area with high illumination, often used for working face lighting.


The light emitting device (small) is used to make the emission concentrated in the beam at the angle of 20 degrees.

Metal halide lamp

A source of radiation that is produced primarily by the excitation of a mixture of metals (e.g., mercury) and halide compounds (such as thallium, indium, sodium halide). For example: HPI-T light source

Metal vapor discharge lamp

A discharge lamp, which is mainly produced by metal vapor, as opposed to a mercury vapor lamp, sodium vapor lamp, etc..

Mirror reflector

The part of the lamp is designed to reflect the light flux of the light source in the desired direction by means of specular reflection.

Mirror factor (S1 and S2)

Reflection factor.

Indirect light


The amount of light transmitted through the reflecting surface of the illumination system to the illuminated surface.

Indirect lighting

The illumination of the lamp with a certain light distribution curve is adopted, which makes the light directly reaching the working surface not to exceed 10% of the total luminous flux without considering the boundary of the working surface.


In the installation, the distance between the two successive lamps.



Visible radiation

Any radiation that causes visual perception.

Switch start fluorescent lamp

Fluorescent lamp suitable for operation with preheating electrode starter. For example, ''TL' D.

A starting method for igniting a lamp by preheating the filament.

Space coefficient (K)

The geometry of the room is represented and used to calculate the coefficient of utilization or luminous flux utilization.

Unless otherwise stated, the spatial coefficients are given by

K = (L x B) / (H x (L + b))

Among them, l is the length of the room, B is the width of the room, h is the distance between the lamps on the working face.

Note 2

The ceiling space index can be the same computing formula that is now the H is the distance to the ceiling lamps.

Threshold increment (TI)

Number indicating the degree of control of the disability glare.

The threshold contrast

The minimum perceptible contrast of an eye to a given state.



The brightness of

The visual parameters characterizing how much light is emitted from a surface.

Luminance factor (road surface)

Ratio of average luminance to average illuminance in road lighting system.

Luminance reduction factor (R)

Lamp coefficient (q) and the product of cos3g, where G is the angle of incidence of light.

Luminance distribution curve

A curve representing the luminance of a luminaire in a vertical plane, wherein the luminance is represented as a function of the angle between the vertical and the vertical directions.

The brightness threshold

Minimum brightness that can be perceived.

Luminance contrast (c)

In the visual region, the brightness contrast can be expressed as the difference in the relative brightness:

C= (L1-L2) /L2

Where the brightness of the two parts of the area of different sizes:

L1: the brightness of a small area, such as a subject

L2: the brightness of a larger area such as a background

Luminance factor (q)


On a given direction, the direction of the incident light, the brightness of the unit.

Unit: cd/m2/lx

Brightness (L)

The brightness of a light source in a certain direction is the unit projection area of the light source in the direction and the luminous flux emitted in the unit solid angle. Unit: cd/m2

Cold start light source (instantaneous start light source, USA)

Discharge lamp without preheating of electrode.

The use of factor

The ratio of the luminous flux emitted by the luminous flux to the lamp.

Halogen lamp

Gas filled lamp containing tungsten filament and a small amount of halogen.

Tungsten halogen lamp

Gas filled tungsten lamp bulb containing halogen or halogen compound.


A unit of luminous flux equal to the luminous flux of a uniform light source with a light intensity of 1cd.


The light produced after being excited by light emission and sustained for a certain period of time.

Solid angle

The angle of the projection area on the surface of the sphere at the center of the sphere of the unit radius

Unit: spherical degree, Sr.



Bright vision

The eye is adapted to at least a few Candela per square meter of brightness. The vision is mainly regulated by cone cells.

diffuse reflection

Device for changing the spatial distribution of radiation by diffusion.

Diffused illumination

There is no visible light from a particular direction in the working face or the illuminated object.

Diffuse (scattering)

The change of the spatial light distribution occurs when a beam is changed into a variety of directions by a surface or medium without changing the frequency of its monochromatic light.

Diffuse transmission

There is no regular transmission in the macroscopic angle.

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