1. Luminous intensity detection light intensity is the intensity of light, which refers to the amount of light emitted within a certain angle. Because the light of LED is concentrated, the inverse square law is not suitable for short distance. Cie127 standard provides two conditions for measuring average normal light intensity: measurement condition a (far field condition) and measurement condition B (near field condition). In both cases, the detector area is 1cm2. In general, standard condition B is used to measure the luminous intensity
2. Detection of luminous flux and efficiency the luminous flux is the sum of the luminous quantity emitted by the light source, that is, the luminous quantity. The detection methods mainly include the following two kinds: (1) integral method. The standard lamp and the measured lamp are ignited in turn in the integrating sphere, and their readings in the photoelectric converter are recorded as es and ED respectively. If the standard luminous flux is called φ s. The luminous flux of the lamp under test φ d = ed × φ s/es。 The integration method adopts the principle of "point light source", which is easy to operate, but the measurement error is large due to the color temperature deviation between the standard lamp and the measured lamp（ 2) Spectrophotometry. The luminous flux is determined by the spectral energy P（ λ) Distribution calculation. The spectrum of 380 nm ~ 780 nm of the standard lamp is measured on the integrating sphere with a monochromator, and then the spectrum of the lamp under test is measured under the same conditions, and the luminous flux of the lamp under test is calculated by comparison. Luminous efficiency is the ratio of luminous flux emitted by light source to power consumed. Constant current method is usually used to measure the luminous efficiency of LED.
3. Detection of spectral characteristics the detection of spectral characteristics of LED includes spectral power distribution, color coordinates, color temperature, color rendering index, etc. Spectral power distribution means that the light source is composed of many different wavelengths of color radiation, and the radiation power of each wavelength is also different. When the light sources are arranged in wavelength order, this difference is called the spectral power distribution of the light sources. Compare and measure the light source with spectrophotometer (monochromator) and standard lamp. The color coordinate is the amount of the luminous color of the light source expressed numerically on the coordinate diagram. There are many kinds of coordinate systems representing colors, usually using X and Y coordinate systems. Color temperature is the number of light source color tables (appearance color representation) seen by human eyes. When the light from the light source is the same color as the light from the black body at a certain temperature, the temperature is the color temperature. In the field of lighting, color temperature is an important parameter to describe the optical characteristics of light source. The theory of color temperature comes from blackbody radiation, and can be obtained from the color coordinates including blackbody trajectory through the color coordinates of light source. The color rendering index represents the amount of light emitted by the light source that correctly reflects the color of the illuminated object. It is usually represented by the general color rendering index RA, which is the arithmetic mean of the color rendering indexes of eight color samples. Color rendering index is an important parameter of light source quality, which determines the application range of light source. Improving the color rendering index of white light-emitting diodes is one of the important tasks in the research and development of light-emitting diodes.
4. The influence of temperature on the optical properties of LED. A large number of experiments show that temperature will affect the emission spectrum and color coordinates of LED.
5. Measurement of electrical parameters of LED lamp. Electrical parameters mainly include forward voltage, reverse voltage and reverse current, which are related to the normal operation of LED lamp, and are one of the basis to judge the basic performance of LED lamp. There are two kinds of electrical parameter measurement of LED lamp: voltage parameter under a certain current; When the voltage is constant, test the current parameters. The specific methods are as follows: (1) DC voltage. When the forward current is applied to the led to be detected, a voltage drop will appear at both ends of the LED. Adjust the power supply determined by the current value, and record the relevant readings on the DC voltmeter, which is the DC voltage of the LED lamp. According to the common sense, when the LED is conducting in the forward direction, the resistance is small, and the external connection method of the ammeter is more accurate（ 2) Reverse current. Apply reverse voltage to the tested LED lamp and adjust the regulated power supply. The reading of the ammeter is the reverse current of the LED under test. Similar to the DC voltage measurement, the LED has a large resistance when conducting in the reverse direction, so the ammeter is used for internal connection.