Goniophotometer can also be called a variable Angle photometer,it is used to measure the light source or the special equipment of the luminaries spatial distribution. Using the data of spatial luminous intensity distribution can be calculated a series of luminous intensity specifications, such as: zonal luminous flux、the intensity distribution of luminaries、the luminous intensity curve of luminaries、regional luminous flux, etc. It is a necessary condition luminosity experiments test equipment . It is also an important tool in lighting engineering design. In the luminaries design and illumination design, the luminosity distribution measurement of luminaries is an important link in quality control.
The principle of goniophotometer: The luminous body’s shapes there are linear type、spheroid、oval、etc, But, if put them in a large enough hypothetical sphere, because of different luminous body shape error is negligible, so treat it as a point light source. This is the principle of Goniophotometer, make the luminous intensity as standards, According to the relationship between the total luminous flux and the intensity of illumination, and make the point source in an imaginary ball heart and let it is divide into several small area, Measuring the intensity of illumination, and then multiplied by the corresponding small area, Finally, add up all these data . This is the total luminous flux that sent out from illuminant and luminaries.