How to test the luminous angle quickly? In the laboratory environment, with the help of angle distribution tester, in the ordinary environment, we can use a simple method, that is, using the characteristics of white paper fluorescence response to ultraviolet light, the paper vertical lamp bead out of the smooth surface and center alignment. The angle of the blue and white area visible to the naked eye is the light angle. As shown in the following diagram, it is easy to see that the luminous angle of the dark purple hemispherical lens lamp bead is about 60 degrees.