1. Luminous intensity detection: Light intensity is the intensity of light, which refers to the amount of light emitted at a certain angle. Because the light of the LED is concentrated, the inverse square law does not apply at close distances. The CIE127 standard stipulates two measurement averaging methods for the measurement of light intensity: measurement condition A (far field condition) and measurement condition B (near field condition). For the condition of light intensity, the detector area for both conditions is 1c

m2. Normally, standard condition B is used to measure the luminous intensity of LED lamps.

2. Luminous flux and light effect detection: Luminous flux is the sum of the amount of light emitted by the light source, that is, the amount of light emitted. The detection methods mainly include the following two:

Integral method. Light the standard lamp and the lamp under test in turn in the integrating sphere, and record their readings in the photoelectric converter as Es and ED, respectively. The standard light flux is known Φs, then the luminous flux of the tested lamp is ΦD=ED×Φs/Es. The integration method utilizes the principle of "point light source" and is easy to operate, but is affected by the color temperature deviation between the standard lamp and the lamp under test, and the measurement error is large.

Spectroscopy. The luminous flux is calculated from the spectral energy P(λ) distribution. Using a monochromator, measure the 380nm-780nm spectrum of the standard lamp in the integrating sphere, then measure the spectrum of the lamp under test under the same conditions, and compare and calculate the luminous flux of the lamp under test.

The luminous efficiency is the ratio of the luminous flux emitted by the light source to the power consumed, and the luminous efficiency of the LED is usually measured by a constant current method.

3. Spectral characteristic detection: The spectral characteristic detection of LED includes spectral power distribution, color coordinates, color temperature, color rendering index, etc.

The spectral power distribution indicates that the light of the light source is composed of color radiation of many different wavelengths, and the radiation power of each wavelength is also different. The light source was measured by comparison with a spectrophotometer (monochromator) and a standard lamp.

Color coordinates are the quantities that numerically represent the color of light emitted by a light source on a coordinate graph. There are various coordinate systems for coordinate graphs representing colors, usually X and Y coordinate systems are used.

Color temperature is the amount that expresses the color table (appearance color representation) of the light source seen by the human eye. When the light emitted by the light source is the same color as the light emitted by an absolute black body at a certain temperature, that temperature is the color temperature. In the field of lighting, color temperature is an important parameter to describe the optical properties of light sources. The relevant theory of color temperature is derived from black body radiation, which can be obtained from the color coordinates of the light source including the black body locus by the color coordinates of the light source.

The color rendering index indicates the amount of light emitted by the light source that correctly reflects the color of the illuminated object. It is usually expressed by the general color rendering index Ra, which is the arithmetic mean of the color rendering index of the light source to 8 color samples. The color rendering index is an important parameter of the quality of the light source, which determines the application range of the light source. Improving the color rendering index of white LEDs is one of the important tasks of LED research and development.

4. Light intensity distribution test: The relationship between light intensity and spatial angle (direction) is called false light intensity distribution, and the closed curve formed by this distribution is called light intensity distribution curve. Because there are many measuring points, and each point is processed by data, an automatic goniophotometer is usually used for measurement.

5. The influence of temperature effect on the optical characteristics of LED: Temperature will affect the optical characteristics of LED. A large number of experiments can show that the temperature affects the LED emission spectrum and color coordinates.

6. Surface brightness measurement: The brightness of the light source in a certain direction is the luminous intensity of the light source in the unit projection area of the direction. Generally, a surface brightness meter and an aiming brightness meter are used to measure the surface brightness.