LED tube parameter test requirements and methods
1. Spectral measurement
Spectral measurement is the basis for the study of light sources. The analysis of spectral power data can provide the amount of luminosity and chromaticity,
It can also give the color rendering of the light source, the estimated data on the harmful health of exposure to radiation and the composition of the light source.
information. The instrument for this measurement is a spectroradiometer, which consists of a monochromator, photodetector
And a device that can convert the output readings into relative spectral power values.
The role of the monochromator is to disperse the uniform radiation from the light source into a spectrum, providing a separation of known bandwidth
Band. The monochromator generally consists of an entrance slit, a collimating device, and a movable dispersive element.
It consists of a photographic lens and an exit slit.
2. Colorimeter
A simple and cheap colorimeter can be composed of three light detectors, which have the International Illumination Commission 1931
The spectral response of the published color matching function. It can be obtained by mounting the filter on the photovoltaic cell. If you use
Such a photometer measures the light source, and the current obtained from the three photocells is proportional to the tristimulus values X, Y, Z,
From this tristimulus value, the chromaticity coordinates x, y, z can be calculated.
3. Spectrophotometer
The spectrophotometer is used to measure the spectral reflectance. Its optical principle is the same as that of a spectroradiometer.
The light emitted by the corresponding light source is dispersed and then directly projected onto the sample or white standard surface. This is done by putting
The dispersive beam is divided into two parts, or the dispersive beam is refracted alternately on two surfaces. From
The ratio of readings can calculate the reflectance of each wavelength in the entire spectral range.
If the material being measured scatters light, it is necessary to use a small integrating sphere to collect the reflected light. Spectrophotometer also
It can be used to measure the large spectral transmittance of materials. When irradiated with a standard light source, measure the spectral transmission of the material
The chromaticity of the transparent material can be determined by calculating its chromaticity. Publications in the International Commission on Illumination
In (CIE, 1977c), the ideal lighting and geometric conditions for collecting light in spectrophotometry are discussed.
4. Illuminance meter
The illuminance meter is usually composed of a photocell with a wire and an electric meter used to read the illuminance. It can be used directly for lighting
Take measurements on site. A simple illuminance meter can use a selenium photovoltaic cell, and a high-precision illuminance meter can use a silicon photovoltaic cell.
5. Luminance meter
Luminance meter is an instrument used to measure the brightness of a light source or the surface of an object. Using a luminance meter, you can see through the instrument
The area to be measured, sometimes this area is very small and must be observed from a long distance, so the luminance meter has
Lens and optical system, and use some form of diaphragm to isolate the measured area.
The working principle of the luminance meter is to measure the illuminance produced by the image of the surface to be measured on the surface of the photocell. This is like light
The illuminance generated on the surface of the battery is proportional to the brightness L of the measured surface and the aperture of the lens.
6. Goniophotometer
Goniophotometer is used to measure the light intensity around the luminaire, and draw the measured data in a suitable method for lighting
Engineers use. The equipment required to measure street lighting and indoor lighting fixtures is the same, and they are all polar coordinates
Photometer. What floodlights and airport signal lamps need is special equipment with long light path-angular distribution span meter.
6.1 Polar coordinate photometer
The simplest polar coordinate photometer is composed of a photovoltaic cell placed at one end of a long arm or on an arc track.
The photocell can rotate around the lamp to measure the light intensity at a known angle. The lamp is fixed on a rotating flat
On the stage, readings at any azimuth angle can be obtained. It is extremely important that only the light to be measured shines on
On the photocell. To exclude other stray light, you can add a baffle in front of the photovoltaic cell. Placement of the baffle
The position should be as limited as possible to the field of view to be consistent with the light cone emitted by the luminaire. In order to avoid the influence of stray light,
The polar coordinate photometer should be placed in a dark room.
6.2 Angular Distribution Photometer
Floodlights, translucent lamps, car headlights and other condensing lamps, they are concentrated, so the test distance should be
Much larger than astigmatism lamps. The detector should be far enough to see the entire reflective surface of the reflector. right
The narrow-angle floodlights commonly used in stadium lighting should have a measuring distance of about 33 meters. However, according to the international
It is stipulated that the test distance of car headlights is 25 meters. An important issue with long optical paths is that the photovoltaic cells should be fixed,
The lamp turns.
7. Integrating sphere
Integrating sphere is also called luminous sphere or spherical photometer. It is a hollow, complete and large spherical shell, the inner wall of which is painted white
Diffuse reflection layer, and the points on the inner wall of the ball diffuse evenly.
Using the integrating sphere, the luminous flux of the measuring light source can be compared.
Put the standard light source and the light source to be measured into the same position in the integrating sphere, and measure that they are the same on the spherical shell.
Point the illuminance, and then compare it.
2. Color measurement
1. Standard lighting body and standard light source
In daily life, people usually observe the color of objects under different phases of sunlight or artificial light sources. different
Time-phase light sources have different spectral distributions. Therefore, the same object can present different colors under different light sources.
color. Therefore, the International Commission on Illumination has formulated several standard illuminators and corresponding light sources for people
We can calibrate the color of the object under the agreed standard illuminator or standard light source.
2. Colorimeter
A simple and cheap colorimeter can be composed of three light detectors, which have the International Illumination Commission 1931
The spectral response of the published color matching function. It can be obtained by mounting the filter on the photovoltaic cell. If you use
Such a photometer measures the light source, and the current obtained from the three photocells is proportional to the tristimulus values X, Y, Z,
From this tristimulus value, the chromaticity coordinates x, y, z can be calculated.
3. Color thermometer
For the tungsten filament light source, the thermal radiation spectrum whose spectral power distribution is close to the blackbody radiation can be used with a simple "double
Color method" to measure color temperature. The two-color method does not need to measure the power distribution of the entire spectrum, but only needs to measure two waves
Long relative spectral power. It is the basic principle of the color thermometer.
Measurement of light source color rendering
If light sources with different spectral power distributions are used to illuminate objects, generally speaking, the color perception produced is different
of. This characteristic of the light source that determines the color of the illuminated object is called the color rendering or color rendering of the light source, also known as color transmission
sex. Light sources with different spectral power distributions can have the same color table, but light sources with the same color table, their display
The chromaticity may be completely different.
The methods for evaluating the color rendering of light sources can be divided into two categories: one is the spectral band method, and the other is the test color method. The former will be tested
The spectral power distribution of the visible light part of the light source is divided into 8-10 bands, one by one with the same base with good color rendering
The quasi-light source is compared to determine the color rendering of the light source. The latter specifies an appropriate number of object colors as test colors,
The color rendering property of the light source can be quantitatively measured from the chromaticity difference produced when the light source to be measured and the reference light source are separately illuminated.
With the above tests, the light parameters of the LED tube can be called up to the standard
