Led Fluorescent Lamp Parameters Test Requirements, Methods
Writer：Jane Time：2021-07-28 Browse：205
1. Spectral measurement
Spectral measurement is the basis of studying light source. Analysis of spectral power data can provide quantities of luminosity and chromaticity,
It is also possible to give an estimate of the chromogenic properties of the light source, the health effects of exposure to radiation and the composition of the light source
Information. The instrument for making such measurements is a spectral radiometer, which consists of a monochromator, a photodetector
And a device that converts an output reading into a relative spectral power value.
The role of the monochromator is to turn the uniform radiation dispersion from the source into a spectrum, providing separation of known bandwidth
Could you take. A monochromator usually consists of an incident slit, a collimating device, a movable dispersion element,
Consists of a photographic lens and an exit slit.
2. Colorimeter
A simple and inexpensive colorimeter can be constructed from three light detectors, which have the international Lighting Commission 1931
Spectral response of the published color matching function. Can be obtained by attaching a filter to a photovoltaic cell. If you use
Such a photometer measures the light source, and the current obtained from the three cells is proportional to the triple stimulus values X, Y, Z,
The chromaticity coordinates x, y, and z can be calculated from the trisstimulus values.
3. Spectrophotometer
A spectrocolorimeter is used to measure spectral reflectance. It works on the same optical principle as a spectral radiometer
The light emitted by the corresponding source is dispersed and then projected directly onto the sample or white standard surface. It through the
The dispersive beam splits into two identical parts, or alternately refracts the dispersive beam on two surfaces, respectively. from
The ratio of readings can be used to calculate the reflectance of each wavelength over the entire spectrum.
If the material being measured scatters light, it is necessary to collect the reflected light with a small integrating sphere. Spectrophotometer also
It can be used to measure large spectral transmittance of materials. The spectral transmission of the material is measured when irradiated with a standard light source
Rate and calculate its chromaticity, you can determine the chromaticity of transparent material. Publications in the International Commission on Lighting
(CIE, 1977C), discusses the ideal geometric conditions for lighting and collecting light in spectrophotometry.
4. Light meter
An illuminance meter usually consists of a photocell with a wire and an electricity meter used to read the illuminance. It can be used directly for lighting
Take measurements on site. Simple illuminance meters can use selenium photocells, and more accurate illuminance meters use silicon photocells.
5. Luminance meter
Luminance meter is an instrument used to measure the brightness of light sources or surfaces. Using a luminance meter, you can see through the instrument
The area to be measured, sometimes this area is small and must be observed from a distance, so the luminance meter has
A lens and an optical system with some form of optical bar to isolate the area being measured.
The luminance meter works by measuring the illumination generated by the image of the surface being measured on the surface of the photocell. This image is in light
The illumination generated on the surface of the cell is proportional to the brightness of the surface being measured and the aperture of the optical bar of the lens.
6. Distribution photometer
A distribution photometer is used to determine the intensity of light around the luminaire and to draw the measured data in an appropriate manner for illumination
Used by engineers. The same equipment is needed to determine street lighting and indoor lighting fixtures, both in polar coordinates
Spectrophotometer. What is required for floodlights and airfield signal lamps is specialized equipment with long light paths - angular spread meters.
6.1 Polar coordinate photometer
The simplest polar coordinate photometer consists of a cell mounted on one end of a long arm or on a curved track, such as this
The cells can be rotated around the luminaire to measure the intensity of light at a known Angle. The luminaire is fixed on a rotating level
On the platform, readings can be taken at any azimuth. It is extremely important that only the light being measured shines
On a photovoltaic cell. To exclude stray light, a baffle can be placed in front of the cell. Placement of baffle
The position shall be such that the field of view is limited as much as possible to the light cone emitted by the luminaire. To avoid the effects of stray light,
The polar coordinate photometer should be located in a dark room.
6.2 Angle distribution photometer
Floodlights, transluminaires, automotive headlights and other converters, which concentrate light, should be tested at a distance
Far more than astigmatism luminaires. The detector should be far enough away to see the entire reflective surface of the reflector. right
For narrow Angle floodlights commonly used in stadium lighting, the measuring distance should be about 33 meters, however, according to the international
According to the regulations, the test distance of car headlights is 25 meters. An important problem with long light paths is that the cells should be fixed,
The lamp rotates.
7. Integrating sphere
The integrating sphere is also called the light passing sphere or spherical photometer. It is a large hollow spherical shell with a white inner wall
Diffuse reflection layer, and the inner wall of the ball diffuse uniform point.
Using the integrating sphere, the luminous flux of the measured source can be compared.
The standard light source and the light source to be measured are respectively placed in the same position in the integrating sphere, and their similarity on the spherical shell is measured
Point of illumination, and then compare.
Measurement of color
1. Standard lighting body and standard light source
In daily life, people usually observe the colors of objects under different phases of sunlight or artificial light sources. different
The light source of time phase has different spectral distribution, therefore, the same object can present different color under different light source
Color. Therefore, the international lighting committee has developed several standard lighting body and the corresponding several light sources for people
We can calibrate the color of an object under a standard illumination or standard light source.
2. Colorimeter
A simple and inexpensive colorimeter can be constructed from three light detectors, which have the international Lighting Commission 1931
Spectral response of the published color matching function. Can be obtained by attaching a filter to a photovoltaic cell. If you use
Such a photometer measures the light source, and the current obtained from the three cells is proportional to the triple stimulus values X, Y, Z,
The chromaticity coordinates x, y, and z can be calculated from the trisstimulus values.
3. The color temperature meter
For the tungsten filament type light source, the thermal radiation spectrum whose spectral power distribution is close to that of the blackbody radiation can be used by simple "double"
Color method "to measure color temperature. The two-color method does not measure the power distribution of the whole spectrum, but only two waves
Long relative spectral power. It is the basic principle of the color thermometer.
Determination of chromogenic properties of light sources
If light sources with different spectral power distributions are used to illuminate objects, in general, the color perception will be different. This determines the light source of the object color characteristics, known as the light source of color or color, also known as color
Sex. Light sources with different spectral power distributions can have the same color table, but have the same color table of light sources, their display
Color can be completely different.
There are two kinds of methods to evaluate the color rendering of light source: one is spectral band method, the other is test color method. The former will be tested
The spectral power distribution of the visible part of the light source is divided into 8-10 wave bands, one by one with good color rendering basis
Compared with quasi-light source, the color rendering of light source can be determined. The latter specifies an appropriate number of object colours to be used as test colours,
The chromaticity of the light source is measured quantitatively from the chromaticity difference between the light source to be measured and the reference light source.
With the above test, the light parameters of LED fluorescent lamp can be called standard
