List of other terms of illumination (O-T)
Source: Date:2017-03-28



Average luminance factor (Q0)

The road surface luminance factor Q is defined as the average value of luminance at the specified incident angle.

Average illuminance (Eav)

Specify the average illuminance on the surface.

Inverse square law

A law that represents the inverse of the square of a variable to another. The inverse square law of the square is expressed in terms of a plane perpendicular to the line between the light source and the point of illumination, which is inversely proportional to the square of the distance between the source and the plane.


Polishing (for road lighting)

Lamp property indicating the degree of light being thrown in the longitudinal direction of the road. Lamps can be divided into three categories: short polishing, medium polishing and long polishing.

Planck locus (blackbody locus)

The locus of the color coordinates of the blackbody radiation at different temperatures.

Planck (in BOLD)

For all incident radiation, regardless of wavelength, or the polarization direction, the thermal radiator absorbs completely. At a given temperature, the maximum radiated power for all wavelengths and incident directions.


Detection of brightness or color change.

Stroboscopic effect

When observers observe a movement, the effect will be different from the true value of the velocity due to the presence of the effect. Due to the presence of light from a fluorescent lamp operating at 50 Hz, the stroboscopic effect leads to erroneous observations of the motion. Fluorescent lamps driven by electronic ballasts do not produce this effect. Due to the use of high frequency, the electronic ballast produces a uniform luminous flux.



Inclination angle

The angle of upward tilt of the lamp.

Area map

The distribution of the luminous flux of the lamp or the lamp is shown in the diagram, and the variation of the luminous flux emitted in the cone with the half apex angle of the cone is shown in the figure.


Device for starting a discharge lamp. The device provides the necessary preheating of the electrodes, and generates voltage peaks together with the ballast.

Start time

The time required for the lamp to start and stabilize. According to the time it is possible to distinguish between thermal (pre heating) start and cold (no preheating) start-up designs. The cold start design has the advantage of quick start, which is suitable for the long working time and few switching cycles. Hot start electronic ballast for a long time (up to 2 seconds), but suitable for frequent switching applications.

Starting current

Appears in the ballast's instantaneous start process, usually lasts 5-10 milliseconds, depending on the circuit design of the ballast.

Starting device (also called trigger)

Electronic device for providing conditions for starting discharge.

Diving lamp

Lamp capable of being used for underwater diving at specified depth. Waterproof lamps.

Sphericity (SR)

The international unit of the angle of a sphere that is equal to the square of the radius of the sphere.

Dome lighting

Lighting system for light from a ledge or recess block, upper part of the distribution of light over the ceiling and wall.



Cosine law of incident light

The illumination of a point on a plane is proportional to the cosine of the incident angle (the angle between the incident ray and the normal of the plane).

E = (I/d2).Cosa

thermal radiation

1 the thermal disturbance produced by matter particles (atoms, molecules, ions, etc.) is the process of the emission of radiant energy.

2 radiation emitted by the process.



Upper [lower] (light) flux

For light source. Luminous flux above [below] the horizontal plane passing through the light source.

Note: it is important that the plane should be specified in each case.

Disability glare

Destroy the visual effects of the subject, and not necessarily cause discomfort glare.

Radio frequency interference (RFT)

Electromagnetic interference in air. Obey FCC or IEC rules. Consideration should be given to the selection of ballast for wireless telemetry equipment. These include radio, television, cell phones, pocket phones, medical devices, etc..

Instant start

Using the input high voltage method to start the light source without preheating the filament.


The color stimulus values are defined by the chromaticity coordinates or in combination with their primary (or complementary) wavelengths and the corresponding excitation purity.

Chromaticity diagram

The color stimulus value and the color value of the results of the combination of planar graph, the chromaticity value can be expressed by a single point on the map.


1 the propagation of a monochromatic light in a medium that changes its transmission speed and is determined by the frequency of the radiation.

2 this phenomenon depends on the nature of the medium.

Color temperature

The temperature of the blackbody is the same as that of the blackbody radiation.

Unit: Kelvin, K.

The color table

The impression of the color produced by the observation of a light source.


The characteristic of visual perception that is similar to the red, green, blue, or some combination of a region.


For one or both eyes. An object can be extended to other spatial angles when viewed with a single eye or eyes. The field may be monocular or binocular.


A thin film of the back of the eye that is sensitive to light stimuli, including photoreceptors (cones and rods) and nerve cells that stimulate the optic nerve.

Visual reliability

For motorists. The driver is more or less conscious of the ability to continuously select or process the visual information presented to him, which is essential for the driver to control the vehicle safely.

Visual guidance

A method for providing a clear, timely, and easy to identify road ahead for road users.

vision system

A group of structures made up of certain parts of the eye, optic nerve, and brain, which can convert light stimuli into complex neural stimuli that are subject to visual perception.

Visual comfort

Visual satisfaction resulting from visual environment.

Visual performance

Quantitative assessment of visual system in the performance of visual tasks.

visual angle

The solid angle of the observed object.

Visual acuity

1 qualitative

The ability to distinguish very close objects.

2 quantitative

The eye is just the reciprocal of the angle between two adjacent objects (points or lines), usually in radians.

Input power

The power consumed by the light source ballast or system is mainly determined by the ballast factor, which usually reduces the input power and causes the light output to drop.

input voltage

Input voltage from a power supply or transmission line to a ballast.

Adaptive regulation (eyes)

The focal length of the eye is generally spontaneous, so as to obtain the maximum visual sensitivity at different distances.

Adapt (eyes)

1 the process in which the state of a visual system is adjusted with respect to brightness or its color stimulus.

2 the final state of the adjustment process

Stopping distance

When a vehicle needs to be stopped, the distance from the driver's awareness of the need to stop the vehicle to the location of the vehicle to stop the total distance.

Focus light fixture

Lamp with reflection or refraction method for improving light intensity in limited solid angle.

Projected area

The orthogonal projection area of the light emitting surface in a plane perpendicular to the direction of the lamp.

Light source coated with reflective material

A portion of the bulb shell is coated with a diffuse or specular reflective material to control the light. Example: HPL-R, MLR, and 'TL' D lights.

Specific luminaire index (SLI)

Indicates the degree of ease of glare control.


Device for changing light source luminous flux output in lighting system.

Transparent medium

A medium that transmits visible radiation mainly through regular transmission, usually having a high regular transmittance in the spectral range of interest.

Transmission factor (formerly known as transfer factor)

The ratio of the radiant flux or flux to the incident flux.

Lens plate

Refractive system consisting of one or more cylindrical Finel lenses.

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