For the lighting industry, lamps and lanterns play a very important role. A good lighting design is realized by choosing the appropriate lamps. Choosing the appropriate lamps and lanterns and building a reasonable and comfortable lighting environment, can not only meet the needs of People’s Daily life, but also provide a safe, energy-saving and high-efficiency visual environment. The nature of the light emitted from lamp and control of the light depend on the type of light source , the reflection of lamps and light transmitting system and various dimmer devices, etc, the main reaction and the light curve of the lamps. Light distribution curve is actually the distribution situation of the light emitted by the light source or lamps in space. It can record the luminous flux, the quantity of the light source, power, power factor, lamps and lanterns size, lamps efficiency including the information such as lamps manufacturers. Most importantly, it has recorded the light intensity of the lamps and lanterns in all directions. In order to understand the specific performance of the lamps, we must adopt scientific test method; choose the suitable instrument equipment to get the accurate the lamps light distribution curve and distribution photometric characteristics. The distribution photometric measurement is the key link of the quality control in lamps and illumination design.
The basic principle of goniophotometer measurement: install a photometric detector in the position of a certain distance from the measured lamps center. The light signal is incident to the probe, and is conversed and processed by the detector according to a certain relationship, and gets the light luminous intensity value and the illuminance value of the incident light signal. Through the variable angle measuring device that can move in two directions, all kinds of light distribution curve and charts can be made. The principle of realizing the total flux ( Flux Meter ) of lamps can be divided into the light intensity integral method and the illumination integral method. The principle can be expressed as the followings:
Intensity integral formula:
Illumination integral formula: